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Quintero Angulo, G., A. Pérez Martínez, H. Pérez Rojas i D. Manreza Paret. "(Self-)Magnetized Bose–Einstein condensate stars". International Journal of Modern Physics D 28, nr 10 (lipiec 2019): 1950135. http://dx.doi.org/10.1142/s0218271819501359.
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We study magnetic field effects on the Equations-of-State (EoS) and the structure of Bose–Einstein Condensate (BEC) stars, i.e. a compact object composed by a gas of interacting spin-one bosons formed up by the pairing of two neutrons. To include the magnetic field in the thermodynamic description, we assume that particle–magnetic field and particle–particle interactions are independent. We consider two configurations for the magnetic field: one where it is constant and externally fixed, and another where it is produced by the bosons through self-magnetization. Stable configurations of self-magnetized and magnetized nonspherical BEC stars are studied using structure equations that describe axially symmetric objects. In general, the magnetized BEC stars are spheroidal, less massive and smaller than the nonmagnetic ones, being these effects more relevant at low densities. Nevertheless, star masses around two solar masses are obtained by increasing the strength of the boson–boson interaction. The inner magnetic field profiles of the self-magnetized BEC stars can be computed as a function of the equatorial radii. The values obtained for the core and surface magnetic fields are in agreement with those typically found in compact objects.
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Hamber, Herbert W., i Reiko Toriumi. "Composite leptons at the LHC". Modern Physics Letters A 29, nr 07 (7.03.2014): 1450034. http://dx.doi.org/10.1142/s0217732314500345.
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In some models of electroweak interactions the W and Z bosons are considered composites, made up of spin-[Formula: see text] subconstituents. In these models a spin-0 counterpart of the W and Z boson naturally appears, whose higher mass can be attributed to a particular type of hyperfine spin interaction among the various subconstituents. Recently, it has been argued that the scalar state could be identified with the newly discovered Higgs (H) candidate. Here, we use the known spin splitting between the W/Z and H states to infer, within the framework of a purely phenomenological model, the relative strength of the spin–spin interactions. The results are then applied to the lepton sector, and used to crudely estimate the relevant spin splitting between the two lowest states. Our calculations in many ways parallels what is done in the SU(6) quark model, where most of the spin splittings between the lowest lying baryon and meson states are reasonably well-accounted for a simple color hyperfine interaction, with constituent (color-dressed) quark masses.
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Ozansoy, A., V. Arı i V. Çetinkaya. "Search for Excited Spin-3/2 Neutrinos at LHeC". Advances in High Energy Physics 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/1739027.
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We study the potential of the nextepcollider, namely, LHeC, with two optionss=1.3 TeV ands=1.98 TeV, to search for excited spin-1/2 and spin-3/2 neutrinos. We calculate the single production cross-section of excited spin-1/2 and spin-3/2 neutrinos according to their effective currents describing their interactions between gauge bosons and SM leptons. We choose theν⋆→eWdecay mode of excited neutrinos andW→jjdecay mode ofW-boson for the analysis. We put some kinematical cuts for the final state detectable particles and plot the invariant mass distributions for signal and the corresponding backgrounds. In order to obtain accessible limits for excited neutrino couplings, we show thef-f′andciV-ciAcontour plots for excited spin-1/2 and excited spin-3/2 neutrinos, respectively.
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YANG, ZHENWEI, JIANPING CHENG i XIANGMING SUN. "SPIN INTERACTION EFFECTS ON MOMENTUM CORRELATIONS FOR IDENTICAL FERMIONS EMITTED IN RELATIVISTIC HEAVY-ION COLLISIONS". Modern Physics Letters A 22, nr 02 (20.01.2007): 131–39. http://dx.doi.org/10.1142/s0217732307020920.
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The Hanbury-Brown and Twiss (HBT) effects predict a Bose–Einstein enhancement of the two-particle momentum correlations of identical bosons at small relative momentum. However, the parallel momentum correlations between identical fermions are less argued. The momentum correlations can be altered by many factors, among which the spin interaction effects are discussed in this paper. It is found that the spin interaction plays an important role on the momentum correlations of identical fermions. For spin triplet state, a full Fermi–Dirac suppression represents as expected. On the contrary, a fake Bose–Einstein enhancement shows up for spin singlet state. The measured momentum correlations of fermions could hence provide some hints of spin interactions between them if all other factors such as Coulomb interactions were removed. Spin interactions make it more complicated to extract physical information from momentum correlations between fermions.
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VORRATH, TILL, TOBIAS BRANDES i BERNHARD KRAMER. "DYNAMICS OF A LARGE-SPIN-BOSON SYSTEM IN THE STRONG COUPLING REGIME". International Journal of Modern Physics B 17, nr 28 (10.11.2003): 5489–93. http://dx.doi.org/10.1142/s0217979203020624.
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We investigate collective effects of an ensemble of biased two-level systems interacting with a bosonic bath in the strong coupling regime. The two level systems are described by a large pseudo-spin J. An equation for the expectation value M(t) of the z-component of the pseudo spin is derived and solved numerically for an ohmic bath at T=0. In case of a large cut-off frequency of the spectral function, a Markov approximation is justified and an analytical solution is presented. We find that M(t) relaxes towards a highly correlated state with maximum value ±J for large times. However, this relaxation is extremely slow for most parameter values so as if the system was "frozen in" by interaction with the bosonic bath.
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LEMKE, E. H. "PHOTOPRODUCTION OF WEAK VECTOR BOSONS IN A SPINOR THEORY". International Journal of Modern Physics A 08, nr 22 (10.09.1993): 3883–908. http://dx.doi.org/10.1142/s0217751x93001570.
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We put forward the hypothesis that the weak W boson be a compound of two 2-component Lorentz spinors. The resulting novel γWW vertex is no gauge field structure. Nevertheless, the Born amplitude of γγ→WLWL respects partial-wave unitarity. As in the Yang-Mills case, the amplitude consists of a direct term, a crossed term, and a sea-gull term, and no unobserved particles are to be involved to get the “good” high-energy behavior. This is due to an imaginary pseudoscalar γWW interaction term. Significant differences between angular distributions and total cross sections of the non-Abelian case and the case of the composite bosons are displayed. The unitarity constraint applied to the reaction γγ→WTWT leads to the prediction of the existence of a composite charged weak scalar Φ±. It constitutes the spin 0 state of the constituents forming W±. Furthermore, the existence of a second and heavy scalar-vector pair ω-X is predicted. These weak boson states are found to exclude the presence of a seagull graph. In the threshold region, the total cross section of γγ→WW in the compositeness case is smaller than in the non-Abelian case. In a broad intermediate energy region it can be larger. Upper unitarity mass-bounds are estimated. They suggest mΦ≈mw so that Φ± might be discovered by forthcoming experiments. The structure of the γΦW, γXW and γωW transition vertices can be inferred without making recourse to unitarity. However, unitarity requires that the mass relation mΦ/mW=mω/mX be valid.
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KOTA, V. K. B. "TWO-BODY ENSEMBLES WITH GROUP SYMMETRIES FOR CHAOS AND REGULAR STRUCTURES". International Journal of Modern Physics E 15, nr 08 (listopad 2006): 1869–83. http://dx.doi.org/10.1142/s0218301306005241.
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The simplest of the two-body random matrix ensembles (TBRE) is the embedded Gaussian orthogonal ensemble of two-body interactions [EGOE(2)] for spinless fermion systems. With m fermions in N single particle states, EGOE(2) and similarly EGUE(2) [the embedded Gaussian unitary ensemble] are generated by the SU(N) algebra. For these ensembles results, obtained using SU(N) Wigner-Racah algebra, for lower order cross correlations between spectra with different particle numbers are given. For fermions with spin degree of freedom one has EGOE(2)-s and similarly EGUE(2)-s, both generated by U(2Ω) ⊃ U(Ω) ⊗ SU(2) algebra with SU(2) generating m particle spins S and 2Ω = N. For these ensembles numerical and first analytical results for cross correlations between spectra with different particle numbers and spins are given. As further extensions, it is possible to construct EGOE(2)-(s,p) generated by U(2Ω) ⊃ [U(Ω) ⊃ SO(Ω)] ⊗ SU(2) where SO(Ω) corresponds to pairing, for nuclear shell model the EGOE(2)-JT generated by U(N) ⊃ SOJ(3) ⊗ SUT(2) algebra etc. On the other hand EGOE's with extended group symmetries of the shell model and the interacting boson models of nuclei, in particular via trace propagation for energy centroids give new insights into regular structures seen in the ground state region of nuclei. Several new examples for energy centroids generated by random 2 and 3-body interactions are given.
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BARENTZEN, HEINZ, i VIKTOR OUDOVENKO. "A SELF-CONSISTENT ANALYTIC THEORY OF THE SPIN BIPOLARON IN THE t–J MODEL". International Journal of Modern Physics B 14, nr 08 (30.03.2000): 809–35. http://dx.doi.org/10.1142/s0217979200000674.
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The spin bipolaron in the t–J model, i.e., two holes interacting with an antiferromagnetic spin background, is treated by an extension of the self-consistent Born approximation (SCBA), which has proved to be very accurate in the single-hole (spin polaron) problem. One of the main ingredients of our approach is the exact form of the bipolaron eigenstates in terms of a complete set of two-hole basis vectors. This enables us to eliminate the hole operators and to obtain the eigenvalue problem solely in terms of the boson (magnon) operators. The eigenvalue equation is then solved by a procedure similar to Reiter's construction of the single-polaron wave function in the SCBA. As in the latter case, the eigenvalue problem comprises a hierarchy of infinitely many coupled equations. These are brought into a soluble form by means of the SCBA and an additional decoupling approximation, whereupon the eigenvalue problem reduces to a linear integral equation involving the bipolaron self-energy. The numerical solutions of the integral equation are in quantitative agreement with the results of previous numerical studies of the problem. The d-wave bound state is found to have the lowest energy with a critical value J/t| c ≈ 0.4. In contrast to recent claims, we find no indication for a crossover between the d-wave and p-wave bound states.
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ADLER, STEPHEN L. "FERMION-SECTOR FRUSTRATED SU(4) AS A PREONIC PRECURSOR OF THE STANDARD MODEL". International Journal of Modern Physics A 14, nr 12 (10.05.1999): 1911–34. http://dx.doi.org/10.1142/s0217751x99000968.
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We give a model for composite quarks and leptons based on the semisimple gauge group SU(4), with the preons in the 10 representation; this choice of gauge gluon and preon multiplets is motivated by the possibility of embedding them in an N=6 supergravity multiplet, with the preons and antipreons both in the 20 of SU(6). Hypercolor singlets are forbidden in the fermionic sector of this theory; we propose that the SU(4) symmetry spontaneously breaks to SU (3)× U (1), with the binding of triality nonzero preons and gluons into composites, and with the formation of a color singlet condensate that breaks the initial Z12 vacuum symmetry to Z6. The spin ½ fermionic composites have the triality structure of a quark–lepton family, and the initial Z12 symmetry implies that there are six massless families, which mix to give three distinct families below the scale of the condensate. The spin 1 triality zero composites of the color triplet SU(4) gluons, when coupled to the condensate and with the color singlet representation of the 10 acting as a doorway state, lead to weak interactions of the fermionic composites through an SU(2) gauge algebra. The initial Z12 symmetry implies that this SU(2) gauge algebra structure is doubled, which in turn permits the corresponding independent gauge bosons to couple to chiral components of the composite fermions. Since the U(1) couples to the 10 representation as B-L, an effective SU (2)L× SU (2)R × U (1)B-L electroweak theory arises at the condensate scale, with all composites having the correct electric charge structure. Assuming a mechanism for forming composite Higgs bosons, the Z12→ Z6 symmetry breaking chain implies that below the condensate scale there can be two sets of discrete chiral Z6 triplets of Higgs doublets, as required by a phenomenological model for the CKM matrix that we have analyzed in detail elsewhere. A renormalization group analysis of the SU(4) model shows that the conversion by binding of one 10 of SU(4) to 12 triplets of SU(3) can give a very large, calculable hierarchy ratio between the SU(4) and the hadronic mass scales.
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Winterberg, F. "Substratum Approach to a Unified Theory of Elementary Particles". Zeitschrift für Naturforschung A 43, nr 12 (1.12.1988): 1131–50. http://dx.doi.org/10.1515/zna-1988-1219.
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If special relativity is a dynamic symmetry caused by true physical deformations of bodies in absolute motion through a substratum or ether, the question if all interactions and elementary particles arc excitations of this ether must be raised. The ether being the cause of all the observed relativistic effects should then obey an exactly nonrelativistic law of motion, and which permits it to consist of positive and negative masses. The fundamental constants of nature, which according to Planck are 1) Newton's constant (G), 2) the velocity of light (c) and 3) Planck’s constant (ћ), suggest that the ether is made up of densely packed positive and negative Planck masses (Planckions), each with a diameter equaling the Planck length. Symmetry demands that the number of positive and negative Planck masses should be equal, making the cosmological constant equal to zero. Because the Planckions are nonrelativistic spin-zero bosons, the ether would therefore consist of two superfluids, one for the positive mass Planckions, and the other one for the negative mass Planckions. By spontaneous symmetry breaking this superfluid ether can in its ground state form a lattice of small vortex rings, with the vortex core radius equaling the Planck length. Force fields of massless vector gauge bosons can be interpreted as quantized transverse vortex waves propagating through this lattice. Because the smallest wave length would be about equal the ring radius of the circular vortices, the ring radius would assume the role of a unification scale. The ring radius is estimated to be about 103 times the Planck length, in fairly good agreement with the empirical evidence for the value of the grand unification scale of the standard model.Charge is explained by the zero point fluctuations of the Planckions attached to the vortex rings, wrhich thereby become the source of virtual phonons. Charge quantization is explained as the result of circulation quantization. Spinors result from bound states of the positive and negative masses of the substratum, and special relativity as a dynamic symmetry would be valid for all those objects. Quantum electrodynamics is derived as a low energy approximationIf spinors are made up from the positive and negative masses of the vortex ring resonance energy, whereby the spinors would assume the character of excitons, the spinor mass can be computed in terms of the Planck mass. Vice versa, with the lowest quark mass m given, a value for the gravitational constant in terms of m, ћ, and c can be obtained. The existence of different particle families can be understood by internal excitations of the spinors, and parity violation may find its explanation in a small nonzero vorticity of the ether. Bacause of its simple fundamental symmetry the theory is unique, it is always finite and has no anomalies.In the proposed theory all fields and interactions are explained in a completely mechanistic way by the Planck masses and their contact interactions. With special relativity as a derived dynamic symmetry and space remaining euclidean, the proposed approach can be seen as an alternative to Einstein’s program to explain all fields and their interactions by symmetries and singularities of a noneuclidean spacetime manifold.In Part I, the fundamental equation for the substratum, which has the form of a nonrelativistic nonlinear Heisenberg equation, is formulated. It is shown how it leads to a Maxwell-type set of equations for the gauge bosons. In Part II, Dirac-type spinors and quantum electrodynamics are derived. These results are then applied to obtain the lowest quark mass in terms of the Planck mass.
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Kalaga, Joanna K., Wiesław Leoński i Radosław Szczęśniak. "Quantum steering in an asymmetric chain of nonlinear oscillators". Photonics Letters of Poland 9, nr 3 (30.09.2017): 97. http://dx.doi.org/10.4302/plp.v9i3.759.
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We discuss here a possibility of generation of steerable states in asymmetric chains comprising three Kerr-like nonlinear oscillators. We show that steering between modes can be generated in the system and it strongly depends on the asymmetry of internal couplings in our model. We can lead to the appearance of new steering effects, which were not present in symmetric models already studied in the literature. Full Text: PDF ReferencesE. Schrödinger, "Discussion of Probability Relations between Separated Systems", Math. Proc. Camb. Phil. Soc. 31, 555 (1935). CrossRef M.D. Reid, "Demonstration of the Einstein-Podolsky-Rosen paradox using nondegenerate parametric amplification", Phys. Rev. A 40, 913 (1989). CrossRef E.G. Cavalcanti, M.D. Reid, "Uncertainty relations for the realization of macroscopic quantum superpositions and EPR paradoxes", Journal of Modern Optics 54, 2373 (2007). CrossRef S.P. Walborn, A. Salles, R.M. Gomes, F. Toscano, P.H. Souto Ribeiro, "Revealing Hidden Einstein-Podolsky-Rosen Nonlocality", Phys. Rev. Lett. 106, 130402 (2011). CrossRef H.M. Wiseman, S.J. Jones, A.C. Doherty, "Steering, Entanglement, Nonlocality, and the Einstein-Podolsky-Rosen Paradox", Phys. Rev. Lett. 98, 140402 (2007). CrossRef S.J. Jones, H.M. Wiseman, A.C. Doherty, "Entanglement, Einstein-Podolsky-Rosen correlations, Bell nonlocality, and steering", Phys. Rev. A 76, 052116 (2007). CrossRef J.K. Kalaga, W. Leoński, "Quantum steering borders in three-qubit systems", Quantum Inf Process 16, 175 (2017). CrossRef Q. He, Z. Ficek, "Einstein-Podolsky-Rosen paradox and quantum steering in a three-mode optomechanical system", Phys. Rev. A 89, 022332 (2014). CrossRef S. Kiesewetter, Q.Y. He, P.D. Drummond, M.D. Reid, "Scalable quantum simulation of pulsed entanglement and Einstein-Podolsky-Rosen steering in optomechanics", Phys. Rev. A 90, 043805 (2014). CrossRef K. Bartkiewicz, A. Cernoch, K. Lemr, A. Miranowicz, F. Nori, "Experimental temporal quantum steering", Scientific Reports 6, 38076 (2016). CrossRef A. Barasiński, B. Brzostowski, R. Matysiak, P. Sobczak, D. Woźniak, In: R. Wyrzykowski, J. Dongarra, K. Karczewski, J. Wasniewski editor, Parallel Processing and Applied Mathematics (PPAM 2013), Lecture Notes in Computer Science, vol 8385. Springer, Berlin, Heidelberg (2014). CrossRef A. Drzewiński, J. Sznajd, "On the real-space renormalization-group study of some 2D quantum spin systems", Physica A 170, 415 (1991). CrossRef G.J. Milburn, C.A. Holmes, "Quantum coherence and classical chaos in a pulsed parametric oscillator with a Kerr nonlinearity", Phys. Rev. A 44, 4704 (1991). CrossRef W. Leoński, "Quantum and classical dynamics for a pulsed nonlinear oscillator", Physica A 233, 365 (1996). CrossRef A. Kowalewska-Kudłaszyk, J.K. Kalaga, W. Leoński, "Long-time fidelity and chaos for a kicked nonlinear oscillator system", Physics Letters A 373, 1334 (2009). CrossRef J.K. Kalaga, W. Leoński, "Two proposals of quantum chaos indicators related to the mean number of photons: pulsed Kerr-like oscillator case", Proc. SPIE 10142, 101421L (2016). CrossRef A. Barasiński, W. Leoński, T. Sowiński, "Ground-state entanglement of spin-1 bosons undergoing superexchange interactions in optical superlattices", J. Opt. Soc. Am. B 31, 1845 (2014). CrossRef A. Barasiński, W. Leoński, "Symmetry restoring and ancilla-driven entanglement for ultra-cold spin-1 atoms in a three-site ring", Quantum Inf Process 16, 6 (2017). CrossRef D. Woźniak, A. Drzewiński, G. Kamieniarz, "Relaxation Dynamics in the Spin-1 Heisenberg Antiferromagnetic Chain after a Quantum Quench of the Uniaxial Anisotropy", Acta Physica Polonica A 130, 1395 (2016). CrossRef R. Szczęśniak, D. Szczęśniak, E.A. Drzazga, "Superconducting state in the atomic metallic hydrogen just above the pressure of the molecular dissociation", Solid State Communications 152, 2023 (2012). CrossRef A. P. Durajski, R. Szczęśniak, M.W. Jarosik, "Properties of the superconducting state in compressed sulphur", Phase Transitions 85, 727 (2012). CrossRef R. Szczęśniak, A. P. Durajski, "The thermodynamic properties of the high-pressure superconducting state in the hydrogen-rich compounds", Solid State Sciences 25, 45 (2013). CrossRef X. Wang, A. Miranowicz, H.R. Li, F. Nori, "Multiple-output microwave single-photon source using superconducting circuits with longitudinal and transverse couplings", Phys. Rev. A 94, 053858, (2016). CrossRef Y.X. Liu, X.W. Xu, A. Miranowicz, F. Nori, "From blockade to transparency: Controllable photon transmission through a circuit-QED system", Phys. Rev. A 89, 043818 (2014). CrossRef M.K. Olsen, "Spreading of entanglement and steering along small Bose-Hubbard chains", Phys. Rev. A 92, 033627 (2015). CrossRef E.G. Cavalcanti, Q.Y. He, M.D. Reid, H.M. Wiseman, "Unified criteria for multipartite quantum nonlocality", Phys. Rev. A 84, 032115 (2011). CrossRef
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GNANAPRAGASAM, G., i M. P. DAS. "COLLECTIVE MODES OF TRAPPED INTERACTING BOSONS". International Journal of Modern Physics B 22, nr 25n26 (20.10.2008): 4349–57. http://dx.doi.org/10.1142/s0217979208050103.
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The derivation for collective modes of an interacting Bose gas trapped by an isotropic harmonic oscillator potential is presented using field-theoretic method. The presence of the two-body scattering term beyond the mean-field is seen to appear inevitably in the calculations, even in the simplest approximation. As a result we see the occurrence of a small number of non-condensate atoms in the ground state density fluctuations.
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Thang, Nguyen Toan, i Pham Thi Thanh Nga. "Supersolids of Hard Core - Bosons on a Triangular Lattice". Communications in Physics 21, nr 4 (30.12.2011): 301. http://dx.doi.org/10.15625/0868-3166/21/4/361.
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We study the boson model on a triangular lattice interacting only via on-site hardcore repulsion by mapping to a system of spins $(S = 1/2)$. We investigate the supersolid phase of the systems which is a state matter displaying both diagonal long- range (solid) order as well as off-diagonal long-range (superfluidity) by utilizing a semionic representation for the spin-XXZ model. We show that the supersolid order is stable in the mean-field theory for a broad region of parameters. The inclusion of spin wave corrections modifies this picture, but the supersolid phase is still quite robust on the triangular lattices.
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Schlottmann, P. "Mixture of interacting supersymmetric spinless fermions and bosons in a one-dimensional trap". Modern Physics Letters B 30, nr 25 (20.09.2016): 1630007. http://dx.doi.org/10.1142/s0217984916300076.
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We consider a gas mixture consisting of spinless fermions and bosons in one dimension interacting via a repulsive [Formula: see text]-function potential. Bosons and fermions are assumed to have equal masses and the interaction strength between bosons and among bosons and fermions is the same. Using the Bethe ansatz solution of the model, we study the ground state properties, the dressed energy potentials for the two bands of rapidities, the elementary particle and hole excitations, the thermodynamics, the finite size corrections to the ground state energy leading to the conformal towers, and the asymptotic behavior at large distances of some relevant correlation functions. The low-energy excitations of the system form a two-component Luttinger liquid. In an elongated optical trap the gas phase separates as a function of the distance from the center of the trap.
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ZHAI, HUI. "SPIN-ORBIT COUPLED QUANTUM GASES". International Journal of Modern Physics B 26, nr 01 (10.01.2012): 1230001. http://dx.doi.org/10.1142/s0217979212300010.
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In this review we will discuss the experimental and theoretical progresses in studying spin–orbit coupled degenerate atomic gases during the last two years. We shall first review a series of pioneering experiments in generating synthetic gauge potentials and spin–orbit coupling in atomic gases by engineering atom-light interaction. Realization of spin–orbit coupled quantum gases opens a new avenue in cold atom physics, and also brings out a lot of new physical problems. In particular, the interplay between spin–orbit coupling and inter-atomic interaction leads to many intriguing phenomena. By reviewing recent theoretical studies of both interacting bosons and fermions with isotropic Rashba spin–orbit coupling, the key message delivered here is that spin–orbit coupling can enhance the interaction effects, and make the interaction effects much more dramatic even in the weakly interacting regime.
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Qin, Yan, i Sheng-Chang Li. "Quantum phase transition of a modified spin-boson model". Journal of Physics A: Mathematical and Theoretical 55, nr 14 (8.03.2022): 145301. http://dx.doi.org/10.1088/1751-8121/ac5507.
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Abstract We adopt a modified spin-boson model to investigate the quantum phase transition in an ultracold atom-molecule conversion system involving molecule–molecule interaction. We explore the properties of ground state, entanglement entropy, and many-body dynamics, which confirm that the system exhibits a second-order phase transition from a pure atom phase to a mixed atom-molecule phase when the energy detuning is below a critical value. We obtain three scaling laws and the corresponding two critical exponents to characterize the phase transition. In particular, we discuss the effects of both the speed of ground-state dynamical evolution and the strength of molecular interaction on the phase transition. The adiabatic evolution condition is obtained as well. Our results show that the molecular interaction can greatly reduce the upper bound of the adiabatic condition, which provides a theoretical basis for easier observation of the phase transition in experiments.
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Strepparola, E., i M. P. Tosi. "Static and Dynamic Properties of a Two-Dimensional Charged Bose Fluid". Modern Physics Letters B 12, nr 12 (20.05.1998): 459–65. http://dx.doi.org/10.1142/s0217984998000561.
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A complete solution of the Singwi–Tosi–Land–Sjölander approximation is given for the ground state and the elementary excitations of a fluid of charged bosons interacting via the two-dimensional ln (r) Coulomb potential at arbitrarily large coupling strength r s . The results are used to discuss the limitations of a static-mean-field approach in such a strongly correlated system.
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Andres, Beatrice, Martin Weinelt, Hubert Ebert, Jürgen Braun, Alex Aperis i Peter M. Oppeneer. "Strong momentum-dependent electron–magnon renormalization of a surface resonance on iron". Applied Physics Letters 120, nr 20 (16.05.2022): 202404. http://dx.doi.org/10.1063/5.0089688.
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The coupling of electrons to spin excitations and the generation of magnons is essential for spin mixing in the ultrafast magnetization dynamics of 3 d ferromagnets. Although magnon energies are generally much larger than phonon energies, until now their electronic band renormalization effect in 3 d ferromagnets suggests a significantly weaker quasiparticle interaction. Using spin- and angle-resolved photoemission, we show an extraordinarily strong renormalization leading to two-branch splitting of an iron surface resonance at ∼200 meV. Its strong magnetic linear dichroism unveils the magnetic nature and momentum dependence of the energy renormalization. By determining the frequency- and momentum-dependent self-energy due to generic electron–boson interaction to compute the resultant electron spectral function, we suggest that the surface-state splitting can be described by strong coupling to an optical spin wave in an iron thin film.
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SAZDJIAN, H. "THE MASSLESS BOUND STATE FORMALISM IN TWO-PARTICLE RELATIVISTIC QUANTUM MECHANICS". International Journal of Modern Physics A 03, nr 05 (maj 1988): 1235–61. http://dx.doi.org/10.1142/s0217751x88000539.
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We develop, in the framework of two-particle relativistic quantum mechanics, the formalism needed to describe massless bound state systems and their internal dynamics. It turns out that the dynamics here is two-dimensional, besides the contribution of the spin degrees of freedom, provided by the two space-like transverse components of the relative coordinate four-vector, decomposed in an appropriate light cone basis. This is in contrast with the massive bound state case, where the dynamics is three-dimensional. We also construct the scalar product of the theory. We apply this formalism to several types of composite systems, involving spin-0 bosons and/or spin-1/2 fermions, which produce massless bound states.
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Benenti, Giuliano, Gaëtan Caldara i Dima L. Shepelyansky. "Spin-Polarized Ground State for Interacting Electrons in Two Dimensions". Physical Review Letters 86, nr 23 (4.06.2001): 5333–36. http://dx.doi.org/10.1103/physrevlett.86.5333.
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Mazuz-Harpaz, Yotam, Kobi Cohen, Michael Leveson, Ken West, Loren Pfeiffer, Maxim Khodas i Ronen Rapaport. "Dynamical formation of a strongly correlated dark condensate of dipolar excitons". Proceedings of the National Academy of Sciences 116, nr 37 (26.08.2019): 18328–33. http://dx.doi.org/10.1073/pnas.1903374116.
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Strongly interacting bosons display a rich variety of quantum phases, the study of which has so far been focused in the dilute regime, at a fixed number of particles. Here we demonstrate the formation of a dense Bose–Einstein condensate in a long-lived dark spin state of 2D dipolar excitons. A dark condensate of weakly interacting excitons is very fragile, being unstable against a coherent coupling of dark and bright spin states. Remarkably, we find that strong dipole–dipole interactions stabilize the dark condensate. As a result, the dark phase persists up to densities high enough for a dark quantum liquid to form. The striking experimental observation of a step-like dependence of the exciton density on the pump power is reproduced quantitatively by a model describing the nonequilibrium dynamics of driven coupled dark and bright condensates. This unique behavior marks a dynamical condensation to dark states with lifetimes as long as a millisecond, followed by a brightening transition at high densities.
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MAMEDOV, T. A., i M. DE LLANO. "LOWERING OF BOSON-FERMION SYSTEM ENERGY WITH A GAPPED COOPER RESONANT-PAIR DISPERSION RELATION". International Journal of Modern Physics B 21, nr 13n14 (30.05.2007): 2335–47. http://dx.doi.org/10.1142/s0217979207043701.
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Applying two-time Green-function techniques to the Friedberg-T.D. Lee phenomenological Hamiltonian of a many-fermion system, it is shown that positive-energy resonant bosonic pairs associated with four-fermion excitations above the Fermi sea are energetically lower in a ground-state that is a mixture of two coexisting and dynamically interacting many-particle subsystems: a) unpaired fermions and b) composite bosons. It is argued that an interaction between free fermions and bosons excited above the Fermi sea in the mixture, namely, the continuous processes of pair-formation from, and disintegration into, two unpaired electrons, results in a substantially lowering the total system energy. The positive-energy composite bosons begin to appear incoherently below a depairing temperature T* as their coupling- and temperature-dependent number density gradually increases from zero. This leads quite naturally to the pseudogap phenomenon observed in high-Tc cuprates.
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Schlottmann, P. "Threshold singularities in the one-dimensional supersymmetric boson–fermion gas mixture". International Journal of Modern Physics B 32, nr 21 (6.08.2018): 1850221. http://dx.doi.org/10.1142/s0217979218502211.
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A one-dimensional gas mixture consisting of bosons and fermions without spin interacting via a repulsive [Formula: see text]-function potential is considered. The model is integrable and soluble via two nested Bethe ansatz, if all particles are assumed to have equal masses and the interaction strength between the bosons and among the bosons and fermions is the same. The low energy excitation spectrum is a two-component Luttinger liquid and can be parametrized by a conformal field theory with conformal charges c = 1. In the low-energy limit, where the band curvature terms in the dispersion can be neglected, the linear dispersion of a Luttinger liquid is asymptotically exact. The spectral function, however, displays deviations from the Luttinger behavior for higher energy excitations. In the neighborhood of the single-particle (hole) energy, the spectral function is represented by an effective X-ray edge type model. Expressions of the critical exponents for the single-hole Green’s function are obtained using the Bethe ansatz solution in the limit of the bosonic gas. The results could be of relevance in the context of ultracold atoms confined to an elongated optical trap.
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BESPROSVANY, J. "ELECTROWEAKLY INTERACTING SCALAR AND GAUGE BOSONS, AND LEPTONS, FROM FIELD EQUATIONS ON SPIN (5+1)-DIMENSIONAL SPACE". International Journal of Modern Physics A 20, nr 01 (10.01.2005): 77–93. http://dx.doi.org/10.1142/s0217751x05019610.
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Unification ideas motivate the formulation of field equations on an extended matrix-spin space. Demanding that the Poincaré symmetry be maintained, one derives scalar symmetries that are associated with flavor and gauge groups. Boson and fermion solutions are obtained with a fixed representation. A field theory can be equivalently written and interpreted in terms of elements of such a space and is similarly constrained. At 5+1 dimensions, one obtains isospin and hypercharge SU (2)L× U (1) symmetries, their vector carriers, two-flavor charged and chargeless leptons, and scalar particles. Mass terms produce breaking of the symmetry to an electromagnetic U (1), a Weinberg's angle with sin 2(θW)=0.25, and additional information on the respective coupling constants. The particles' underlying spin symmetry gives information on their masses; one reproduces the Standard Model ratio MZ/MW, and predicts possible Higgs masses of MH≈114 and MH≈161 GeV, at tree level.
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LIU, YU-LIANG. "APPLICATION OF EIGENFUNCTIONAL THEORY ON QUANTUM MANY-PARTICLE SYSTEMS". International Journal of Modern Physics B 16, nr 27 (30.10.2002): 4127–63. http://dx.doi.org/10.1142/s0217979202014693.
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We first introduce the basic ingredients of the eigenfunctional theory, and show that a D-dimensional quantum many-particle system is mapped into a (D+1)-dimensional time-depending single-particle problem, and in the representation of the eigenfunctionals of the particle propagator, the particles become free. Then using this method, we study five kinds of quantum many-particle systems: interacting boson system, repulsive, attractive interacting fermion systems, Hubbard model and single-impurity scattering in one-dimensional fermion system, and demonstrate that the microscopic Bogoliubov theory and the phenomenological Bijl–Feynman theory of the bosons are closely related, and apart from an anti-symmetry factor Det ‖eikj·xl‖ the ground state wave function of the repulsive interacting fermion system has a similar form to that of the interacting boson system. Moreover, we show that the attractive interacting fermion system has a sound-type excitation spectrum like that in the interacting boson system. For one-dimensional Hubbard model we calculate the electron Green's function, and charge and spin density–density correlation functions which are consistent with the exact ones obtained by the Bethe ansatz and numerical calculations, and show that the ground state energy is increasing with U, and the electrons has single-occupied constraint in the large U limit. Finally, we demonstrate clearly the evolution of the system from its ultraviolet fixed point to infrared critical fixed point as the impurity potential increases. At the infrared critical fixed point, the fermion Green's function shows that the fermions are completely reflected on the impurity site.
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RIGOL, MARCOS, i ALEJANDRO MURAMATSU. "FREE EXPANSION OF IMPENETRABLE BOSONS ON ONE-DIMENSIONAL OPTICAL LATTICES". Modern Physics Letters B 19, nr 18 (10.08.2005): 861–81. http://dx.doi.org/10.1142/s0217984905008876.
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We review recent exact results for the free expansion of impenetrable bosons on one-dimensional lattices, after switching off a confining potential. When the system is initially in a superfluid state, far from the regime in which the Mott-insulator appears in the middle of the trap, the momentum distribution of the expanding bosons rapidly approaches the momentum distribution of non-interacting fermions. Remarkably, no loss in coherence is observed in the system as reflected by a large occupation of the lowest eigenstate of the one-particle density matrix. In the opposite limit, when the initial system is a pure Mott insulator with one particle per lattice site, the expansion leads to the emergence of quasicondensates at finite momentum. In this case, one-particle correlations like the ones shown to be universal in the equilibrium case develop in the system. We show that the out-of-equilibrium behavior of the Shannon information entropy in momentum space, and its contrast with one of non-interacting fermions, allows to differentiate the two different regimes of interest. It also helps in understanding the crossover between them.
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Pelayo, J. C., i D. M. Yanga. "Linked cluster theory in the spin polaron problem". International Journal of Modern Physics B 33, nr 07 (20.03.2019): 1950044. http://dx.doi.org/10.1142/s0217979219500449.
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The Linked Cluster Theory in the spin polaron formulation is investigated in this paper using the finite temperature (Matsubara) Green’s function method. We use a representation where holes and spins are described as spinless fermions and normal bosons, respectively. An analytic expression of the thermodynamic potential of high-temperature superconductors in the superconducting state was obtained using the Linked Cluster theory and an expression for its normal state by setting the energy gap to zero. The expression of the thermodynamic potential enabled us to calculate two bulk thermodynamic properties of high-temperature superconductors, entropy and specific heat, both in the normal and superconducting states.
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Ciardi, Matteo, Tommaso Macrì i Fabio Cinti. "Zonal Estimators for Quasiperiodic Bosonic Many-Body Phases". Entropy 24, nr 2 (12.02.2022): 265. http://dx.doi.org/10.3390/e24020265.
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In this work, we explore the relevant methodology for the investigation of interacting systems with contact interactions, and we introduce a class of zonal estimators for path-integral Monte Carlo methods, designed to provide physical information about limited regions of inhomogeneous systems. We demonstrate the usefulness of zonal estimators by their application to a system of trapped bosons in a quasiperiodic potential in two dimensions, focusing on finite temperature properties across a wide range of values of the potential. Finally, we comment on the generalization of such estimators to local fluctuations of the particle numbers and to magnetic ordering in multi-component systems, spin systems, and systems with nonlocal interactions.
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SEIRINGER, ROBERT. "A CORRELATION ESTIMATE FOR QUANTUM MANY-BODY SYSTEMS AT POSITIVE TEMPERATURE". Reviews in Mathematical Physics 18, nr 03 (kwiecień 2006): 233–53. http://dx.doi.org/10.1142/s0129055x06002632.
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We present an inequality that gives a lower bound on the expectation value of certain two-body interaction potentials in a general state on Fock space in terms of the corresponding expectation value for thermal equilibrium states of non-interacting systems and the difference in the free energy. This bound can be viewed as a rigorous version of first-order perturbation theory for many-body systems at positive temperature. As an application, we give a proof of the first two terms in a high density (and high temperature) expansion of the free energy of jellium with Coulomb interactions, both in the fermionic and bosonic case. For bosons, our method works above the transition temperature (for the non-interacting gas) for Bose–Einstein condensation.
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Gerlich, D., F. Windisch, P. Hlavenka, R. Plašil i J. Glosik. "Dynamical constraints and nuclear spin caused restrictions in collision systems". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, nr 1848 (20.09.2006): 3007–34. http://dx.doi.org/10.1098/rsta.2006.1865.
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This contribution summarizes a variety of results and ongoing activities, which contribute to our understanding of inelastic and reactive collisions involving hydrogen ions. In an overview of our present theoretical knowledge of various collision systems ( m + n ≤5), it is emphasized that although the required potential energy surfaces are well characterized, no detailed treatments of the collision dynamics are available to date, especially at the low energies required for astrochemistry. Instead of treating state-to-state dynamics with state of the art methods, predictions are still based on: (i) simple thermodynamical arguments, (ii) crude reaction models such as H atom exchange or proton jump, or (iii) statistical considerations used for describing processes proceeding via long-lived or strongly interacting collision complexes. A central problem is to properly account for the consequences of the fact that H and D are fermions and bosons, respectively. In the experimental and results sections, it is emphasized that although a variety of innovative techniques are available and have been used for measuring rate coefficients, cross-sections or state-to-state transition probabilities, the definitive experiments are still pending. In the centre of this contribution are our activities on various m + n =5 systems. We report a few selected additional results for collisions of hydrogen ions with p -H 2 , o -H 2 , HD, D 2 or well-defined mixtures of these neutrals. Most of the recent experiments are based on temperature variable multipole ion traps and their combination with pulsed gas inlets, molecular beams, laser probing or electron beams. Based on the state-specific model calculations, it is concluded that for completely understanding the gas phase formation and destruction of in a trap, an in situ characterization of all the experimental parameters is required with unprecedented accuracy. Finally, the need to understand the hydrogen chemistry relevant for dense pre-stellar cores is discussed.
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Lode, Axel U. J., Sunayana Dutta i Camille Lévêque. "Dynamics of Ultracold Bosons in Artificial Gauge Fields—Angular Momentum, Fragmentation, and the Variance of Entropy". Entropy 23, nr 4 (25.03.2021): 392. http://dx.doi.org/10.3390/e23040392.
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We consider the dynamics of two-dimensional interacting ultracold bosons triggered by suddenly switching on an artificial gauge field. The system is initialized in the ground state of a harmonic trapping potential. As a function of the strength of the applied artificial gauge field, we analyze the emergent dynamics by monitoring the angular momentum, the fragmentation as well as the entropy and variance of the entropy of absorption or single-shot images. We solve the underlying time-dependent many-boson Schrödinger equation using the multiconfigurational time-dependent Hartree method for indistinguishable particles (MCTDH-X). We find that the artificial gauge field implants angular momentum in the system. Fragmentation—multiple macroscopic eigenvalues of the reduced one-body density matrix—emerges in sync with the dynamics of angular momentum: the bosons in the many-body state develop non-trivial correlations. Fragmentation and angular momentum are experimentally difficult to assess; here, we demonstrate that they can be probed by statistically analyzing the variance of the image entropy of single-shot images that are the standard projective measurement of the state of ultracold atomic systems.
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CHAUDHARY, G. K., AMIT K. CHATTOPADHYAY i R. RAMAKUMAR. "BOSE–EINSTEIN CONDENSATE IN A QUARTIC POTENTIAL: STATIC AND DYNAMIC PROPERTIES". International Journal of Modern Physics B 25, nr 29 (20.11.2011): 3927–40. http://dx.doi.org/10.1142/s0217979211101855.
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In this paper, we present a theoretical study of a Bose–Einstein condensate of interacting bosons in a quartic trap in one-, two- and three-dimensions. Using Thomas–Fermi approximation, suitably complemented by numerical solutions of the Gross–Pitaevskii equation, we study the ground-state condensate density profiles, the chemical potential, the effects of cross-terms in the quartic potential, temporal evolution of various energy components of the condensate and width oscillations of the condensate. Results obtained are compared with corresponding results for a bose condensate in a harmonic confinement.
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Alon, Ofir E. "Solvable Model of a Generic Driven Mixture of Trapped Bose–Einstein Condensates and Properties of a Many-Boson Floquet State at the Limit of an Infinite Number of Particles". Entropy 22, nr 12 (26.11.2020): 1342. http://dx.doi.org/10.3390/e22121342.
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A solvable model of a periodically driven trapped mixture of Bose–Einstein condensates, consisting of N1 interacting bosons of mass m1 driven by a force of amplitude fL,1 and N2 interacting bosons of mass m2 driven by a force of amplitude fL,2, is presented. The model generalizes the harmonic-interaction model for mixtures to the time-dependent domain. The resulting many-particle ground Floquet wavefunction and quasienergy, as well as the time-dependent densities and reduced density matrices, are prescribed explicitly and analyzed at the many-body and mean-field levels of theory for finite systems and at the limit of an infinite number of particles. We prove that the time-dependent densities per particle are given at the limit of an infinite number of particles by their respective mean-field quantities, and that the time-dependent reduced one-particle and two-particle density matrices per particle of the driven mixture are 100% condensed. Interestingly, the quasienergy per particle does not coincide with the mean-field value at this limit, unless the relative center-of-mass coordinate of the two Bose–Einstein condensates is not activated by the driving forces fL,1 and fL,2. As an application, we investigate the imprinting of angular momentum and its fluctuations when steering a Bose–Einstein condensate by an interacting bosonic impurity and the resulting modes of rotations. Whereas the expectation values per particle of the angular-momentum operator for the many-body and mean-field solutions coincide at the limit of an infinite number of particles, the respective fluctuations can differ substantially. The results are analyzed in terms of the transformation properties of the angular-momentum operator under translations and boosts, and as a function of the interactions between the particles. Implications are briefly discussed.
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Kaplan, Ilya G. "Modern State of the Pauli Exclusion Principle and the Problems of Its Theoretical Foundation". Symmetry 13, nr 1 (24.12.2020): 21. http://dx.doi.org/10.3390/sym13010021.
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The Pauli exclusion principle (PEP) can be considered from two aspects. First, it asserts that particles that have half-integer spin (fermions) are described by antisymmetric wave functions, and particles that have integer spin (bosons) are described by symmetric wave functions. It is called spin-statistics connection (SSC). The physical reasons why SSC exists are still unknown. On the other hand, PEP is not reduced to SSC and can be consider from another aspect, according to it, the permutation symmetry of the total wave function can be only of two types: symmetric or antisymmetric. They both belong to one-dimensional representations of the permutation group, while other types of permutation symmetry are forbidden. However, the solution of the Schrödinger equation may have any permutation symmetry. We analyze this second aspect of PEP and demonstrate that proofs of PEP in some wide-spread textbooks on quantum mechanics, basing on the indistinguishability principle, are incorrect. The indistinguishability principle is insensitive to the permutation symmetry of wave function. So, it cannot be used as a criterion for the PEP verification. However, as follows from our analysis of possible scenarios, the permission of states with permutation symmetry more general than symmetric and antisymmetric leads to contradictions with the concepts of particle identity and their independence. Thus, the existence in our Nature particles only in symmetric and antisymmetric permutation states is not accidental, since all symmetry options for the total wave function, except the antisymmetric and symmetric, cannot be realized. From this an important conclusion follows, we may not expect that in future some unknown elementary particles that are not fermions or bosons can be discovered.
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Barr, Alan J., Paweł Caban i Jakub Rembieliński. "Bell-type inequalities for systems of relativistic vector bosons". Quantum 7 (27.07.2023): 1070. http://dx.doi.org/10.22331/q-2023-07-27-1070.
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We perform a detailed analysis of the possible violation of various Bell-type inequalities for systems of vector boson-antiboson pairs. Considering the general case of an overall scalar state of the bipartite system, we identify two distinct classes of such states, and determine the joint probabilities of spin measurement outcomes for each them. We calculate the expectation values of the CHSH, Mermin and CGLMP inequalities and find that while the generalised CHSH inequality is not expected to be violated for any of the scalar states, in the case of the Mermin and CGLMP inequalities the situation is different – these inequalities can be violated in certain scalar states while they cannot be violated in others. Moreover, the degree of violation depends on the relative speed of the two particles.
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Aouachria, Mekki. "Exact spin coherent state path integral for a two-level atom in gravitational fields". Canadian Journal of Physics 89, nr 11 (listopad 2011): 1141–48. http://dx.doi.org/10.1139/p11-108.
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The movement of a two-level atom interacting with an electromagnetic wave while subject to gravity is studied using path-integral formalism. The propagator is first written in a standard form, ∫[Formula: see text](path) exp(i/ℏ)S(path), by replacing the spin with a unit vector aligned along the polar and azimuthal directions to determine the propagator exactly. Thus, the exact wave functions of the system are deduced.
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Pasechnik, Roman, Vitaly Beylin, Vladimir Kuksa i Grigory Vereshkov. "Composite scalar dark matter from vector-like SU(2) confinement". International Journal of Modern Physics A 31, nr 08 (14.03.2016): 1650036. http://dx.doi.org/10.1142/s0217751x16500366.
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A toy-model with [Formula: see text] dynamics confined at high scales [Formula: see text] enables to construct Dirac UV completion from the original chiral multiplets predicting a vector-like nature of their weak interactions consistent with electroweak precision tests. In this work, we investigate a potential of the lightest scalar baryon-like (T-baryon) state [Formula: see text] with mass [Formula: see text] predicted by the simplest two-flavor vector-like confinement model as a dark matter (DM) candidate. We show that two different scenarios with the T-baryon relic abundance formation before and after the electroweak (EW) phase transition epoch lead to symmetric (or mixed) and asymmetric DM, respectively. Such a DM candidate evades existing direct DM detection constraints since its vector coupling to [Formula: see text] boson absents at tree level, while one-loop gauge boson mediated contribution is shown to be vanishingly small close to the threshold. The dominating spin-independent (SI) T-baryon–nucleon scattering goes via tree-level Higgs boson exchange in the [Formula: see text]-channel. The corresponding bound on the effective T-baryon–Higgs coupling has been extracted from the recent LUX data and turns out to be consistent with naive expectations from the light technipion case [Formula: see text]. The latter provides the most stringent phenomenological constraint on strongly-coupled [Formula: see text] dynamics so far. Future prospects for direct and indirect scalar T-baryon DM searches in astrophysics as well as in collider measurements have been discussed.
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Суханов, А. А., i В. А. Сабликов. "Спиновые состояния электронов в двойной квантовой точке в двумерном топологическом изоляторе со спин-орбитальным взаимодействием". Физика и техника полупроводников 53, nr 9 (2019): 1257. http://dx.doi.org/10.21883/ftp.2019.09.48134.17.
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AbstractThe spectra and spin structure of the states of two interacting electrons localized in a double quantum dot in a two-dimensional topological insulator with spin-orbit interaction are investigated. It is found that, in such a system, a singlet-triplet transition in the ground state without a magnetic field can be implemented. Spin-orbit interaction leads to the splitting of polarized triplet levels and to anticrossing, when one of them crosses the singlet.
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Schäfer, Frank, Miguel A. Bastarrachea-Magnani, Axel U. J. Lode, Laurent de Forges de Parny i Andreas Buchleitner. "Spectral Structure and Many-Body Dynamics of Ultracold Bosons in a Double-Well". Entropy 22, nr 4 (26.03.2020): 382. http://dx.doi.org/10.3390/e22040382.
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We examine the spectral structure and many-body dynamics of two and three repulsively interacting bosons trapped in a one-dimensional double-well, for variable barrier height, inter-particle interaction strength, and initial conditions. By exact diagonalization of the many-particle Hamiltonian, we specifically explore the dynamical behavior of the particles launched either at the single-particle ground state or saddle-point energy, in a time-independent potential. We complement these results by a characterization of the cross-over from diabatic to quasi-adiabatic evolution under finite-time switching of the potential barrier, via the associated time evolution of a single particle’s von Neumann entropy. This is achieved with the help of the multiconfigurational time-dependent Hartree method for indistinguishable particles (MCTDH-X)—which also allows us to extrapolate our results for increasing particle numbers.
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Arhrib, Abdesslam, Adil Jueid i Stefano Moretti. "Searching for heavy charged Higgs bosons through top quark polarization". International Journal of Modern Physics A 35, nr 15n16 (4.06.2020): 2041011. http://dx.doi.org/10.1142/s0217751x20410110.
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We study the production of a heavy charged Higgs boson at the Large Hadron Collider (LHC) in [Formula: see text] within a 2-Higgs Doublet Model (2HDM). The chiral structure of the [Formula: see text] coupling can trigger a particular spin state of the top quark produced in the decay of a charged Higgs boson and, therefore, is sensitive to the underlying mechanism of the Electroweak Symmetry Breaking (EWSB). Taking two benchmark models (2HDM type-I and 2HDM type-Y) as an example, we show that inclusive rates, differential distributions and forward–backward asymmetries of the top quark’s decay products can be used to search for heavy charged Higgs bosons and also as model discriminators.
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Mankoč Borštnik, N. S. "Understanding nature with the spin-charge-family theory". International Journal of Modern Physics A 33, nr 31 (10.11.2018): 1844027. http://dx.doi.org/10.1142/s0217751x1844027x.
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The spin-charge-family theory, which is a kind of the Kaluza–Klein theories in [Formula: see text] — but with the two kinds of the spin connection fields, the gauge fields of the two Clifford algebra objects, [Formula: see text] and [Formula: see text] — explains all the assumptions of the standard model: The origin of the charges of fermions appearing in one family, the origin and properties of the vector gauge fields of these charges, the origin and properties of the families of fermions, the origin of the scalar fields observed as the Higgs’s scalar and the Yukawa couplings. The theory explains several other phenomena like: The origin of the dark matter, of the matter–antimatter asymmetry, the “miraculous” triangle anomaly cancellation in the standard model and others. The more work is invested in this theory, the more explanations of the observed phenomena the theory is offering. Since the theory starts at [Formula: see text] with a simple action for bosons and fermions, with the fermions carrying only two kinds of spins and no charges and interacting only through gravity (the vielbeins and the two kinds of the spin connection fields) and with the gravity as the only boson fields, the questions arises not only how do the two kinds of spins of fermions in [Formula: see text] manifest the spin, charges and family quantum numbers in [Formula: see text], and how does the gravity in [Formula: see text] manifests as all the observed gauge fields, the scalar fields and the Yukawa couplings, offering also explanation for matter–antimatter asymmetry and the existing of the dark matter, but also why “nature makes a choice of the Clifford algebra rather than the Grassmann algebra” although both kinds of degrees of freedom enable anticommutation relations for fermions, which might explain also the appearance of the dark energy.
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Amghar, B., i M. Daoud. "Quantum state manifold and geometric, dynamic and topological phases for an interacting two-spin system". International Journal of Geometric Methods in Modern Physics 17, nr 02 (31.01.2020): 2050030. http://dx.doi.org/10.1142/s0219887820500309.
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We consider a two-spin system of [Formula: see text] Heisenberg type submitted to an external magnetic field. Using the associated [Formula: see text] geometry, we investigate the dynamics of the system. We explicitly give the corresponding Fubini–Study metric. We show that for arbitrary pure initial states, the dynamics occurs on a torus. We compute the geometric phase, the dynamic phase and the topological phase. We investigate the interplay between the torus geometry and the entanglement of the two spins. In this respect, we provide a detailed analysis of the geometric phase, the dynamics velocity and the geodesic distance measured by the Fubini–Study metric in terms of the degree of entanglement between the two spins.
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Sadiek, Gehad, i Samaher Almalki. "Asymptotic steady state of a dissipative long-range interacting spin system at finite temperature". Physica Scripta 98, nr 9 (24.08.2023): 095113. http://dx.doi.org/10.1088/1402-4896/acf010.
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Abstract Many of the recently developed quantum systems that are considered promising candidates for the underlying technology of quantum computing enjoy long-range interaction, which is even tunable in some of them. Most of these systems can be described using the Heisenberg spin model to represent their interaction with the same system or a different one in hybrid structures. We consider here a finite two-dimensional spin system with a varying spin-spin long-range interaction under the effect of an external uniform magnetic field. We investigate the dynamics of the system and its asymptotic behavior at different degrees of anisotropy and interaction range under coupling to a thermal dissipative environment, starting from different initial states. We show that the system spin state and bipartite entanglement evolve in time to reach asymptotic values that are enhanced significantly by the degree of anisotropy and interaction range, whereas the thermal dissipative environment degrades the entanglement asymptotic equilibrium value as the temperature increases. Interestingly, while the robustness of the spin system against the environment’s thermal dissipative effects increases with the interaction range and degree of anisotropy, the entanglement between the far sites on the lattice shows its highest resilience in the partially anisotropic system, which might be attributed to a critical behavior taking place in the system. While the system’s early dynamics varies significantly depending on the initial state, the asymptotic equilibrium value is found to be completely independent.
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ALBAYRAK, ERHAN, SEYMA AKKAYA i SABAN YILMAZ. "SPIN-2 ISING MODEL ON THE BILAYER BETHE LATTICE". International Journal of Modern Physics B 22, nr 24 (30.09.2008): 4189–203. http://dx.doi.org/10.1142/s0217979208039599.
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A spin-2 system consisting of two layers of Bethe lattices each with a branching ratio of q Ising spins was analyzed by the use of the exact recursion relations in a pairwise approach. The upper layer interacting with nearest-neighbor (NN) bilinear interaction J1 is laid over the top of the lower layer interacting with bilinear NN interaction J2, and the two layers are tied together via the bilinear interaction between the vertically aligned adjacent NN spins denoted as J3. The study of the ground state phase diagrams on the (J2/|J3|, J1/|J3|) plane with J3>0 and J3<0 and on the (J2/J1, J3/q J1) plane with J1>0 has yielded five distinct ground state configurations. The temperature dependent phase diagrams are obtained for the case with intralayer coupling constants of the two layers with ferromagnetic type J1 and J2>0, and the interlayer coupling constant of the layers with either ferromagnetic J3>0 or antiferromagnetic type J3<0 on the (kT/J1, J3/J1) planes for given values of the J2/J1 for various values of the coordination numbers. As a result, we have found that the model presents both second- and first-order phase transitions, therefore, tricritical points.
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Maiti, Debasmita, Dayasindhu Dey i Manoranjan Kumar. "Study of Interacting Heisenberg Antiferromagnet Spin-1/2 and 1 Chains". Condensed Matter 8, nr 1 (29.01.2023): 17. http://dx.doi.org/10.3390/condmat8010017.
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Haldane conjectures the fundamental difference in the energy spectrum of the Heisenberg antiferromagnetic (HAF) of the spin S chain is that the half-integer and the integer S chain have gapless and gapped energy spectrums, respectively. The ground state (gs) of the HAF spin-1/2 and spin-1 chains have a quasi-long-range and short-range correlation, respectively. We study the effect of the exchange interaction between an HAF spin-1/2 and an HAF spin-1 chain forming a normal ladder system and its gs properties. The inter-chain exchange interaction J⊥ can be either ferromagnetic (FM) or antiferromagnetic (AFM). Using the density matrix renormalization group method, we show that in the weak AFM/FM coupling limit of J⊥, the system behaves like two decoupled chains. However, in the large AFM J⊥ limit, the whole system can be visualized as weakly coupled spin-1/2 and spin-1 pairs which behave like an effective spin-1/2 HAF chain. In the large FM J⊥ limit, coupled spin-1/2 and spin-1 pairs can form pseudo spin-3/2 and the whole system behaves like an effective spin-3/2 HAF chain. We also derive the effective model Hamiltonian in both strong FM and AFM rung exchange coupling limits.
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Nisperuza, J., J. P. Rubio i R. Avella. "Density probabilities of a Bose-Fermi mixture in 1D double well potential". Journal of Physics Communications 6, nr 2 (1.02.2022): 025004. http://dx.doi.org/10.1088/2399-6528/ac4faf.
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Abstract We use the two mode approximation for a interacting one-dimensional spinless soft core bosons and one half spin fermions in a double-well potential with a large central barrier. We include all the on-site boson-boson, fermion-fermion and boson-fermion repulsive contact potential represented by delta-function and considered bosonic and fermionic isotopes of ytterbium(Yb) 170 Yb and 171 Yb respectively. By means of this approximation, we find that in the regime λ BF > λ BB give rise to a immiscible phase and in the regime λ BB ≥ λ BF give rise to a miscible phase, that is characterized by a temporal overlap of the bosonic and fermionic probability densities. We also report that due to the Bose-Fermi interaction, the system presents an apparent destruction of the collapse-revival oscillation of boson density probability at least in the ranges investigated.
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ZUCCHI, Maria R., Otaciro R. NASCIMENTO, Adelaide FALJONI-ALARIO, Tatiana PRIETO i Iseli L. NANTES. "Modulation of cytochrome c spin states by lipid acyl chains: a continuous-wave electron paramagnetic resonance (CW-EPR) study of haem iron". Biochemical Journal 370, nr 2 (1.03.2003): 671–78. http://dx.doi.org/10.1042/bj20021521.
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This work is a systematic study, showing a clear correlation between the nature of the lipid acyl chain and the spin states of cytochrome c interacting with different types of lipid membranes. According to the lipid acyl chain type, and the head group charge present in the bilayer, three spin states of cytochrome c were observed in different proportions: the native cytochrome c low spin state with rhombic symmetry (spin 1/2, g//=3.07 and g⊥=2.23), a low spin state with less rhombic symmetry (spin 1/2, g1 = 2.902, g2 = 2.225, and g3 = 1.510) and the high spin state (spin 5/2, g// = 6.0 and g⊥ = 2.0). The proportion of the spin states of cytochrome c bound to bilayers was also dependent on the lipid/protein ratio, suggesting the existence of two or more protein sites interacting with the lipids. The lipid-induced alterations in the symmetry and spin states of cytochrome c exhibited partial reversibility when the ionic strength was increased, which reinforces the crucial role played by the electrostatic interaction with the lipid bilayer. Different cytochrome c spin states exhibited corresponding modifications in the haemprotein UV/visible spectra, particularly in the Q-band associated with loss of the 695nm band and appearance of a band in the region of 600—650nm. The observed reactivity of cytochrome c with oxidized forms of unsaturated lipids reinforces the possibility of the acyl chain insertion in the haemprotein structure.
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Liñares, Jesús, Xesús Prieto-Blanco, Gabriel M. Carral i María C. Nistal. "Quantum Photonic Simulation of Spin-Magnetic Field Coupling and Atom-Optical Field Interaction". Applied Sciences 10, nr 24 (10.12.2020): 8850. http://dx.doi.org/10.3390/app10248850.
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In this work, we present the physical simulation of the dynamical and topological properties of atom-field quantum interacting systems by means of integrated quantum photonic devices. In particular, we simulate mechanical systems used, for example, for quantum processing and requiring a very complex technology such as a spin-1/2 particle interacting with an external classical time-dependent magnetic field and a two-level atom under the action of an external classical time-dependent electric (optical) field (light-matter interaction). The photonic device consists of integrated optical waveguides supporting two collinear or codirectional modes, which are coupled by integrated optical gratings. We show that the single-photon quantum description of the dynamics of this photonic device is a quantum physical simulation of both aforementioned interacting systems. The two-mode photonic device with a single-photon quantum state represents the quantum system, and the optical grating corresponds to an external field. Likewise, we also present the generation of Aharonov–Anandan geometric phases within this photonic device, which also appear in the simulated systems. On the other hand, this photonic simulator can be regarded as a basic brick for constructing more complex photonic simulators. We present a few examples where optical gratings interacting with several collinear and/or codirectional modes are used in order to illustrate the new possibilities for quantum simulation.
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ZHANG, GUO-FENG. "QUANTUM ENTANGLEMENT IN THE SYSTEM OF TWO SPIN-1/2 PARTICLES WITH HEISENBERG EXCHANGE INTERACTION IN THE PRESENCE OF A SINGLE-MODE VACUUM FIELD". International Journal of Quantum Information 06, nr 03 (czerwiec 2008): 437–46. http://dx.doi.org/10.1142/s0219749908003657.
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The nonclassical properties of two spin-1/2 particles with Heisenberg exchange interaction in a single-mode vacuum field are investigated. By using the quantum reduced entropy, we demonstrate that the ratio ka between Heisenberg exchange interaction constant difference (J - Jz) and the spin-field coupling constant Ω can affect the feature of the entanglement significantly. It is found that the entanglement of the system evolves periodically with time, the evolvement period of the entanglement between two spin-1/2 particles and the field increases with the increasing ka, which is true for the single spin-field entanglement, but that is contrary for the entanglement between the two spin particles. Our results show that three entangled states of two spins-field, spin–spin, and spin-field can be prepared via two spin-1/2 particles interacting with a single-mode vacuum field. We also characterize the field state by using Mandel's Q parameter, it is proved that the nonclassical properties of the field state will get weaker with the increasing ka and are dramatically different from those in the case of selective measurement for spin.
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Bonatsos, Dennis, i H. Muether. "Microscopic Calculation of the Optical Model Potential from One Boson Exchange Potentials". HNPS Proceedings 1 (18.02.2020): 86. http://dx.doi.org/10.12681/hnps.2827.
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A new method for calculating the optical model potential from One Boson Exchange Potentials (OBEPs) is developed. The G-matrix is calculated by solving the Bethe-Goldstone equation in momentum space. Using vector brackets these G-matrix elements can be transformed from the center of mass representation into the laboratory system. This allows the evaluation of the (r-matrix interaction between nucleons in bound states and those in a plane-wave state. The lowest order contribution to the real part of the potential comes from the Hartree-Fock term, while the lowest order contribution to the imaginary part comes from the two-particle-one-hole (2p1h) diagram. Calculations for 16O and 40Ca have been carried out. Local approximations are obtained by describing the results for the central part in terms of a Woods-Saxon potential and those for the spin-orbit part in terms of the corresponding derivatives. The dependence of these potentials on energy and angular momentum is discussed. The parameters for these local approximations are in good agreement with empirical fits.