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Articoli di riviste sul tema "Quark models"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 31 gennaio 2023

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1

EVANS, P. W., e B. A. ROBSON. "COMPARISON OF QUARK MIXING IN THE STANDARD AND GENERATION MODELS". International Journal of Modern Physics E 15, n. 03 (aprile 2006): 617–25. http://dx.doi.org/10.1142/s0218301306004077.

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The different interpretations of quark mixing involved in weak interaction processes in the Standard Model and the Generation Model are discussed with a view to obtaining a physical understanding of the Cabibbo angle and related quantities. It is proposed that hadrons are composed of mixed-quark states, with the quark mixing parameters being determined by the Cabibbo-Kobayashi-Maskawa matrix elements. In this model, protons and neutrons contain a contribution of about 5% and 10%, respectively, of strange valency quarks.

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2

Metsch, B. "Quark models⋆". European Physical Journal A 35, n. 3 (marzo 2008): 275–80. http://dx.doi.org/10.1140/epja/i2007-10557-4.

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3

BALL, R. D. "MESONS, SKYRMIONS AND BARYONS". International Journal of Modern Physics A 05, n. 23 (10 dicembre 1990): 4391–426. http://dx.doi.org/10.1142/s0217751x90001847.

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We review the construction of low energy effective actions for QCD expressed in terms of mesons and baryons rather than quarks and gluons. The mesons consist of quark-antiquark pairs bound by effective gluon exchange, while the baryons contain three valence quarks, also bound by effective gluon exchange, but enveloped in a meson cloud (the “sea quarks”), which may take the form of a chiral soliton. Such a “chiral quark soliton model” offers a unified approach to the various superficially dissimilar models of baryons currently popular, in particular constituent quark models, chiral bags, and Skyrmions, permitting an objective assessment of which is likely to be the most useful for a given physical problem.

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4

HUANG, HONGXIA, JIALUN PING, HOURONG PANG e FAN WANG. "STUDY OF NΔ AND ΔΔ RESONANCE STATES IN CONSTITUENT QUARK MODELS". Modern Physics Letters A 25, n. 25 (20 agosto 2010): 2155–65. http://dx.doi.org/10.1142/s0217732310033074.

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To look for nonstrange dibaryon resonances, a systematic calculation of nucleon–nucleon scattering phase shifts of two interacting baryon clusters of quarks with explicit coupling to NΔ and ΔΔ states is done. Two phenomenological nonrelativistic quark models giving similar low-energy NN properties are found to give significantly different dibaryon resonance structures. In the chiral quark model, the dibaryon system does not resonate in the NNS waves. In the quark delocalization color screening model, the S wave NN resonances appear with nucleon size b = 0.6. There is a IJ = 12NΔ resonance state in the [Formula: see text] scattering phase shifts at 2168 MeV in this model. Both quark models give an IJ = 03 ΔΔ resonance, which is a promising candidate for the explanation of the ABC structure at ~ 2.36 GeV in the production cross section of the reaction pn → dππ by the CELSIUS-WASA collaboration. None of the quark models used has any bound NΔP states that might generate odd-parity resonances.

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5

PASQUINI, B., S. BOFFI e P. SCHWEITZER. "THE SPIN STRUCTURE OF THE NUCLEON IN LIGHT-CONE QUARK MODELS". Modern Physics Letters A 24, n. 35n37 (7 dicembre 2009): 2903–12. http://dx.doi.org/10.1142/s021773230900111x.

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The quark spin densities related to generalized parton distributions in impact-parameter space and to transverse-momentum dependent parton distributions are reviewed within a light-cone quark model, with focus on the role of the different spin-spin and spin-orbit correlations of quarks. Results for azimuthal spin asymmetries in semi-inclusive deep inelastic scattering due to T -even transverse-momentum dependent parton distributions are also discussed.

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6

LAI, XIAOYU, e RENXIN XU. "QUARK-CLUSTER STARS: THE STRUCTURE". International Journal of Modern Physics: Conference Series 23 (gennaio 2013): 213–22. http://dx.doi.org/10.1142/s2010194513011331.

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The nature of pulsar-like compact stars is still in controversy although the first pulsar was found more than 40 years ago. Generally speaking, conventional neutron stars and non-mainstream quark stars are two types of models to describe the inner structure of pulsars, with the former composed mainly of hadrons and the latter of a peculiar kind of matter whose state equation should be understood in the level of quarks rather than hadrons. To construct a more realistic model from both theoretical and observational points of view, we conjecture that pulsars could be "quark-cluster stars" which are composed of quark-clusters with almost equal numbers of up, down and strange quarks. Clustering quark matter could be the result of strong coupling between quarks inside realistic compact stars. The lightest quark clusters could be of H-dibaryons, while quark clusters could also be heavier with more quarks. Being essentially related to the non-perturbative quantum-chromo dynamics (QCD), the state of supra-nuclear condensed matter is really difficult to obtain strictly by only theoretical QCD-calculations, and we expect, nevertheless, that astrophysical observations could help us to have a final solution.

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7

Contrera, Gustavo A., Milva Orsaria, I. F. Ranea-Sandoval e Fridolin Weber. "Hybrid Stars in the Framework of NJL Models". International Journal of Modern Physics: Conference Series 45 (gennaio 2017): 1760026. http://dx.doi.org/10.1142/s2010194517600266.

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We compute models for the equation of state (EoS) of the matter in the cores of hybrid stars. Hadronic matter is treated in the non-linear relativistic mean-field approximation, and quark matter is modeled by three-flavor local and non-local Nambu−Jona-Lasinio (NJL) models with repulsive vector interactions. The transition from hadronic to quark matter is constructed by considering either a soft phase transition (Gibbs construction) or a sharp phase transition (Maxwell construction). We find that high-mass neutron stars with masses up to [Formula: see text] may contain a mixed phase with hadrons and quarks in their cores, if global charge conservation is imposed via the Gibbs conditions. However, if the Maxwell conditions is considered, the appearance of a pure quark matter core either destabilizes the star immediately (commonly for non-local NJL models) or leads to a very short hybrid star branch in the mass-radius relation (generally for local NJL models).

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8

Weigel, H., e J. P. Blanckenberg. "Heavy baryons with strangeness in soliton models". International Journal of Modern Physics: Conference Series 39 (gennaio 2015): 1560088. http://dx.doi.org/10.1142/s2010194515600885.

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We present some recent results from soliton model calculations for the spectrum of baryons with a single heavy quark. The model comprises chiral symmetry for light flavors and (approximate) heavy spin–flavor symmetry for the heavy quarks. We focus on flavor symmetry breaking for strangeness degrees of freedom.

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9

Tadić, D., e S. Žganec. "Covariant and heavy quark symmetric quark models". Physical Review D 50, n. 9 (1 novembre 1994): 5853–64. http://dx.doi.org/10.1103/physrevd.50.5853.

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10

ZHANG, BIN. "J/ψ PRODUCTION FROM CHARM COALESCENCE IN RELATIVISTIC HEAVY ION COLLISIONS". International Journal of Modern Physics E 16, n. 07n08 (agosto 2007): 2061–65. http://dx.doi.org/10.1142/s0218301307007465.

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J/ψ production is closely related to the production of the strongly interacting Quark-Gluon Plasma (sQGP) in relativistic heavy ion collisions. To study the effects of charm quark dynamics on J/ψ production, the phase space distributions of charm and anti-charm quarks are generated using A Multi-Phase Transport (AMPT) model. These charm quarks then coalesce into J/ψ particles. The production and flow of J/ψ show strong sensitivity to final state charm interactions. The results are compared to charm quark and D meson results from the AMPT model and recent predictions from other models.

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11

Weber, H. J., e K. Bodoor. "Baryon Spin and Magnetic Moments in Relativistic Chiral Quark Models". International Journal of Modern Physics E 06, n. 04 (dicembre 1997): 693–709. http://dx.doi.org/10.1142/s0218301397000330.

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The spin and flavor fractions of constituent quarks in the baryon octet are obtained from their lowest order chiral fluctuations involving Goldstone bosons. SU(3) breaking suggested by the mass difference between the strange and up, down quarks is included, as are relativistic effects by means of a light-cone quark model for the proton, and the gluon contribution from the axial anomaly in the singlet channel. Magnetic moments from the Karl-Sehgal formulas are analyzed in this framework as well.

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12

CONTRERA, G. A., M. ORSARIA e N. N. SCOCCOLA. "NON-LOCAL CHIRAL QUARK MODELS WITH POLYAKOV LOOP AT FINITE TEMPERATURE AND CHEMICAL POTENTIAL". International Journal of Modern Physics D 19, n. 08n10 (agosto 2010): 1703–9. http://dx.doi.org/10.1142/s0218271810017718.

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We analyze the chiral restoration and deconfinement transitions in the framework of a non-local chiral quark model which includes terms leading to the quark wave function renormalization, and takes care of the effect of gauge interactions by coupling the quarks with the Polyakov loop. Non-local interactions are described by considering both a set of exponential form factors, and a set of form factors obtained from a fit to the mass and renormalization functions obtained in lattice calculations.

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13

Afonin, S. S., e I. V. Pusenkov. "Note on universal description of heavy and light mesons". Modern Physics Letters A 29, n. 35 (17 novembre 2014): 1450193. http://dx.doi.org/10.1142/s0217732314501934.

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The experimental spectrum of excited S-wave vector mesons with hidden quark flavor reveals a remarkable property: For all flavors, it is approximately linear in mass squared, [Formula: see text], n is the radial quantum number. We draw attention to the fact that such a universal behavior for any quark mass cannot be obtained in a natural way within the usual semirelativistic potential and string-like models — if the Regge-like behavior is reproduced for the mesons composed of the light quarks, the trajectories become essentially nonlinear for the heavy-quark sector. In reality, however, the linearity for the heavy mesons appears to be even better than for the light ones. In addition, the slope a is quite different for different quark flavors. This difference is difficult to understand within the QCD string approach since the slope measures the interaction strength among quarks. We propose a simple way for reparametrization of the vector spectrum in terms of quark masses and universal slope and intercept. Our model-independent analysis suggests that the quarks of any mass should be regarded as static sources inside mesons while the interaction between quarks is substantially relativistic.

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14

RHO, MANNQUE. "MASSIVE-QUARK BARYONS AS SKYRMIONS". Modern Physics Letters A 06, n. 23 (30 luglio 1991): 2087–100. http://dx.doi.org/10.1142/s0217732391002268.

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Massive-quark baryons containing one or more charm (c) or bottom (b) quarks are described as massive scalar doublet fields "wrapped" by the soliton of the light (up and down) flavors. The spin-isospin transmutation that takes place to make the trapped scalar behave like heavy-flavored quarks is analogous to what happens to a scalar doublet in the presence of a 't Hooft–Polyakov monopole. The Wess–Zumino term plays a pivotal role here. This model predicts spectra that resemble closely those of quark models. This feature is interpreted in terms of an induced gauge (or Berry) structure associated with "fast" and "slow" degrees of freedom corresponding, respectively, to the massive- and light-flavor quarks involved in the baryon structure.

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15

Harko, Tiberiu, Francisco S. N. Lobo e M. K. Mak. "Wormhole geometries supported by quark matter at ultra-high densities". International Journal of Modern Physics D 24, n. 01 (28 dicembre 2014): 1550006. http://dx.doi.org/10.1142/s0218271815500066.

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A fundamental ingredient in wormhole physics is the presence of exotic matter, which involves the violation of the null energy condition (NEC). In this context, we investigate the possibility that wormholes could be supported by quark matter at extreme densities. Theoretical and experimental investigations of the structure of baryons show that strange quark matter, consisting of the u, d and s quarks, is the most energetically favorable state of baryonic matter. Moreover, at ultra-high densities, quark matter may exist in a variety of superconducting states, namely, the Color–Flavor-Locked (CFL) phase. Motivated by these theoretical models, we explore the conditions under which wormhole geometries may be supported by the equations of state (EOS) considered in the theoretical investigations of quark–gluon interactions. For the description of the normal quark matter, we adopt the Massachusetts Institute of Technology (MIT) bag model EOS, while the color superconducting quark phases are described by a first-order approximation of the free energy. By assuming specific forms for the bag and gap functions, several wormhole models are obtained for both normal and superconducting quark matter. The effects of the presence of an electrical charge are also taken into account.

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16

Ping, Jialun, Chengrong Deng, Hongxia Huang, Fangfang Dong e Fan Wang. "Quark models for mesons". EPJ Web of Conferences 20 (2012): 01007. http://dx.doi.org/10.1051/epjconf/20122001007.

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17

Gudrun Kalmbach HE. "Dynamical interaction geometries for physics with models". Magna Scientia Advanced Research and Reviews 1, n. 2 (28 febbraio 2021): 031–37. http://dx.doi.org/10.30574/msarr.2021.1.2.0007.

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The MINT-Wigris Tool bag is presented with its models for color charges as a G-compass the hedgehog for the energy exchange of a nucleon system with its environment, an inner quark-gluon flow in it as 6-roll mill, two nucleon tetrahedrons for the gluon exchange between nucleons quarks, a radial contraction/expansion pulsation for deuteron, two fusion states of the tetrahedrons, a neutrino Gleason operator bound geometry and oscillation dynamics.

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18

MODARRES, M., e H. GHOLIZADE. "STRANGE QUARK MATTER IN THE FRAMEWORK OF ONE GLUON EXCHANGE AND DENSITY AND TEMPERATURE DEPENDENT PARTICLE MASS MODELS". International Journal of Modern Physics E 17, n. 07 (agosto 2008): 1335–55. http://dx.doi.org/10.1142/s0218301308010453.

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We calculate the thermodynamic properties of strange quark matter by using the density and temperature dependent particle mass model of Wen et al. For the interaction Hamiltonian we use the one gluon exchange interaction obtained from the Fermi liquid picture. We let the QCD coupling (αc) be constant or vary with density and temperature. A new set of mass scalings for quarks is evaluated from the present interaction, which can be used with thermodynamic formulas derived by Wen et al. Similar to β-stable matter, no stability is found in strange quark matter. Finally, it is shown that the present equation of state of strange quark matter becomes harder with respect to that obtained using the string model, specially with non-constant QCD coupling.

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19

WEBER, H. J. "PROTON STRUCTURE FUNCTIONS FROM CHIRAL DYNAMICS AND QCD CONSTRAINTS". International Journal of Modern Physics A 14, n. 19 (30 luglio 1999): 3005–27. http://dx.doi.org/10.1142/s0217751x99001469.

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The spin fractions and deep inelastic lepton structure functions of the proton are analyzed using chiral field theory involving Goldstone bosons. A detailed comparison with recent chiral models sheds light on their successful description of the spin fractions of the proton as being due to neglecting helicity nonflip chiral transitions. This approximation is valid for zero mass but not for constituent quarks. Since the chiral spin fraction models with the pure spin-flip approximation reproduce the measured spin fractions of the proton, axialvector constituent-quark-Goldstone boson couplings are found to be inconsistent with the proton spin data. Initial quark valence distributions are then constructed using quark counting constraints at Bjorken x→1 and Regge behavior at x→0. Sea quark distributions predicted by chiral field theory on this basis have the correct order of magnitude and shape. The spin fractions also agree with the data.

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20

Tandy, PC, e MR Frank. "Composite Mesons in Self-confining Chiral Solitons". Australian Journal of Physics 44, n. 3 (1991): 181. http://dx.doi.org/10.1071/ph910181.

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Most quark-meson models for formation of a baryon as a bag or soliton solution begin with elementary local meson fields including a classical scalar configuration that provides repulsion of valence quarks from the vacuum. We explore aspects of the very different formation mechanism that operates in a model where chira\ effective meson fields are composite objects generated from bilocal qq fluctuation fields and the dynamical quark mass can be self-confining. Speculations are made on whether this viewpoint can motivate meson-nucleon relativistic field models containing intrinsic cutoffs for use in nuclear physics.

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21

Ghalenovi, Zahra. "Constituent quark models for hadronic systems". EPJ Web of Conferences 199 (2019): 05011. http://dx.doi.org/10.1051/epjconf/201919905011.

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In this work we introduce two different potential models for hadronic systems such that the QCD concepts of the quark-quark and quark-antiquark interactions be satisfied. We present the simple methods to solve two- and three-body equation of meson and baryon systems respectively. The introduced models are studied in the relativistic and non-relativistic limits.

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22

SALEHI, NASRIN, e ALI AKBAR RAJABI. "PROTON STATIC PROPERTIES BY USING HYPERCENTRAL CONSTITUENT QUARK MODEL AND ISOSPIN". Modern Physics Letters A 24, n. 32 (20 ottobre 2009): 2631–37. http://dx.doi.org/10.1142/s0217732309031016.

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The static properties of protons are useful for understanding the quark structure of the proton. In his work we have introduced the hypercentral constituent quark model and isospin dependent potentials. Here constituent quarks interact with each other via a potential in which we have taken into account the three-body force effect and the standard two-body potential contributions. According to our model the static properties of protons containing u and d quarks are better than the other models and closer to experimental results. The two key ingredients of this improvement are the effective quark–gluon hypercentral potentials, and hyperfine interaction and isospin dependence potential. Recently, Schrödinger equation has been solved by Giannini but we have solved the Dirac equation exact analytically and we have shown that a considerable improvement in the description of the static properties of proton is obtained with an isospin dependent potential and the complete interaction including spin and isospin terms reproduces the position of the quark.

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23

FOOT, R., H. LEW e R. R. VOLKAS. "GLUEBALL MEDIATED DECAY OF MASSIVE NEUTRINOS IN QUARK-LEPTON SYMMETRIC MODELS". International Journal of Modern Physics A 08, n. 05 (20 febbraio 1993): 983–1003. http://dx.doi.org/10.1142/s0217751x93000382.

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The mysterious similarity of quarks and leptons may be invoked to motivate the hypothesis of an exact discrete symmetry between the quarks and the leptons which is broken spontaneously. This hypothesis predicts the existence of heavy bound states and light glueballs associated with an unbroken SU(2)′ gauge symmetry. We show that some of these bound states can mix significantly with the ordinary leptons. An interesting consequence of this mixing is that a massive neutrino can decay surprisingly quickly via real or virtual SU(2)′ glueball emission. Hence, we argue that massive neutrinos in generic quark-lepton symmetric models may decay fast enough to be consistent with the energy density bound in the standard big bang model of cosmology.

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24

BEGUN, V. V., M. I. GORENSTEIN e O. A. MOGILEVSKY. "MODIFIED BAG MODELS FOR THE QUARK–GLUON PLASMA EQUATION OF STATE". International Journal of Modern Physics E 20, n. 08 (agosto 2011): 1805–15. http://dx.doi.org/10.1142/s0218301311019623.

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The modified versions of the bag model equation of state (EoS) are considered. They are constructed to satisfy the main qualitative features observed for the quark–gluon plasma EoS in the lattice QCD calculations. A quantitative comparison with the lattice results at high temperatures T are done in the SU(3) gluodynamics and in the full QCD with dynamical quarks. Our analysis advocates a negative value of the bag constant B.

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25

Fernández, Francisco, e Jorge Segovia. "Historical Introduction to Chiral Quark Models". Symmetry 13, n. 2 (2 febbraio 2021): 252. http://dx.doi.org/10.3390/sym13020252.

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Chiral symmetry, and its dynamical breaking, has become a cornerstone in the description of the hadron’s phenomenology at low energy. The present manuscript gives a historical survey on how the quark model of hadrons has been implemented along the last decades trying to incorporate, among other important non-perturbative features of quantum chromodynamics (QCD), the dynamical chiral symmetry breaking mechanism. This effort has delivered different models such as the chiral bag model, the cloudy bag model, the chiral quark model or the chiral constituent quark model. Our main aim herein is to provide a brief introduction of the Special Issue “Advances in Chiral Quark Models” in Symmetry and contribute to the clarification of the differences among the above-mentioned models that include the adjective chiral in their nomenclature.

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26

HUANG, F., W. L. WANG e Z. Y. ZHANG. "$\bar KN$ SCATTERING IN CHIRAL CONSTITUENT QUARK MODELS". International Journal of Modern Physics A 23, n. 20 (10 agosto 2008): 3057–72. http://dx.doi.org/10.1142/s0217751x08041554.

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The chiral SU(3) quark model and the extended chiral SU(3) quark model have proven to be quite successful in reproducing the binding energy of the deuteron, the nucleon–nucleon (NN) scattering phase shifts and the hyperon–nucleon (YN) cross-sections. In the chiral SU(3) quark model, the quark–quark interaction contains one-gluon exchange (OGE), confinement potential and boson exchanges stemming from scalar and pseudoscalar nonets. In the extended chiral SU(3) quark model, the OGE is nearly replaced by vector meson exchange. It was shown in our previous work that these two models give quite similar descriptions for the S, P, D, F wave KN phase shifts, which means that in the KN system the contribution of OGE can be replaced by that of vector meson exchange. In this paper, we use the same models, the same parameters and the same methods to study the [Formula: see text] system with the purpose to test the effects of OGE and vector meson exchange. The cross-sections for K-p scattering into K-p, K0n, π+Σ-, π-Σ+, π0Σ0 and π0Λ channels are dynamically calculated by solving the resonating group method equation. While some channels are well described in one or the other model, a good agreement between the theoretical cross-sections and the experimental data for all channels is not successfully obtained. The present work indicates that both OGE and vector meson exchange are necessary to be included in the quark–quark interactions if one tries to simultaneously describe the KN phase shifts and [Formula: see text] cross-sections using one set of parameters in a constituent quark model.

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CHEN, MEI, FANG GONG, HONGXIA HUANG e JIALUN PING. "DIBARYONS WITH STRANGENESS IN QUARK MODELS". Modern Physics Letters A 25, n. 19 (21 giugno 2010): 1603–12. http://dx.doi.org/10.1142/s0217732310032913.

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The extended quark delocalization color screening model, which incorporates Goldstone–boson-exchange with soft cutoff, and chiral quark model are employed to do a systematic dynamical calculation of six-quark systems with strangeness. The two models give similar results, although they have different attraction mechanisms. Comparing with the previous calculation of the extended quark delocalization color screening model, in which the Goldstone–bosons are introduced with hard cutoff, the present calculation obtains a little large binding energies for most of the states. However, the conclusions are the same. The calculations show that NΩ state with IJ = 1/2, 2 is a good dibaryon candidate with narrow width, and ΩΩ state with IJ = 00 is a stable dibaryon against the strong interaction. The calculations also reveal several other possible dibaryon candidates with high angular momentum, ΔΣ*(1/2, 3), ΔΞ*(1, 3), etc. These states may have too wide width to be observed experimentally.

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KOMATHIRAJ, K., e S. D. MAHARAJ. "ANALYTICAL MODELS FOR QUARK STARS". International Journal of Modern Physics D 16, n. 11 (novembre 2007): 1803–11. http://dx.doi.org/10.1142/s0218271807011103.

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We find two new classes of exact solutions to the Einstein–Maxwell system of equations. The matter content satisfies a linear equation of state consistent with quark matter; a particular form of one of the gravitational potentials is specified to generate solutions. The exact solutions can be written in terms of elementary functions, and these can be related to quark matter in the presence of an electromagnetic field. The first class of solutions generalizes the Mak–Harko model. The second class of solutions does not admit any singularities in the matter and gravitational potentials at the center.

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SZCZEKOWSKI, MAREK. "DIQUARKS IN ELEMENTARY PARTICLE PHYSICS". International Journal of Modern Physics A 04, n. 16 (10 ottobre 1989): 3985–4035. http://dx.doi.org/10.1142/s0217751x89001643.

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Many phenomena in elementary particle physics show indications of clustering of two quarks inside baryons. Although the existence of such diquark systems cannot be presently rigorously proven in quantum field theory of strong interactions, phenomenological models require some quark-quark binding to explain effects ranging from the baryon mass spectrum to large pT proton production in high energy pp collisions. This review confronts diquark models predictions with experimental results in low and high transverse momentum hadron-hadron collisions, lepton-nucleon scattering and e+e− annihilations. The recent data from the Split Field Magnet detector on high pT proton production in pp, dd and αα collisions at ISR energies are particularly emphasized.

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BAUR, U., I. HINCHLIFFE e D. ZEPPENFELD. "EXCITED QUARK PRODUCTION AT HADRON COLLIDERS". International Journal of Modern Physics A 02, n. 04 (agosto 1987): 1285–97. http://dx.doi.org/10.1142/s0217751x87000661.

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Composite models generally predict the existence of excited quark and lepton states. We consider the production and experimental signatures of excited quarks Q* of spin and isospin 1/2 at hadron colliders and estimate the background for those channels which are most promising for Q* identification. Multi-TeVpp-colliders will give access to such particles with masses up to several TeV.

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KOBAYASHI, TATSUO, e ZHI-ZHONG XING. "QUARK MASS MATRICES IN SUPERSTRING MODELS". International Journal of Modern Physics A 13, n. 13 (20 maggio 1998): 2201–15. http://dx.doi.org/10.1142/s0217751x98000998.

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Four simple but realistic patterns of quark mass matrices are derived from orbifold models of superstring theory in the absence of gauge symmetries. Two of them correspond to the Ramond–Roberts–Ross types, which have five texture zeros in up and down quark sectors. The other two, with four texture zeros, preserve the structural parallelism between up and down sectors. The phenomenological consequences of these mass matrices on flavor mixing and CP violation are analyzed at the weak scale. With the same input values of quark mass ratios, we find that only one or two of the four patterns can be in good agreement with current experimental data.

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Menezes, D. P., C. Providência e D. B. Melrose. "Quark stars within relativistic models". Journal of Physics G: Nuclear and Particle Physics 32, n. 8 (19 giugno 2006): 1081–95. http://dx.doi.org/10.1088/0954-3899/32/8/001.

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33

De Sanctis, E., A. B. Kaidalov e L. A. Kondratyuk. "Deuteron photodisintegration and quark models". Physical Review C 42, n. 4 (1 ottobre 1990): 1764–67. http://dx.doi.org/10.1103/physrevc.42.1764.

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34

Azam, M., S. A. Mardan e M. A. Rehman. "Stability of Quark Star Models". Communications in Theoretical Physics 65, n. 5 (1 maggio 2016): 575–84. http://dx.doi.org/10.1088/0253-6102/65/5/575.

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35

Guichon, P. A. M. "Quark models of nuclear physics". Nuclear Physics A 680, n. 1-4 (gennaio 2001): 229–39. http://dx.doi.org/10.1016/s0375-9474(00)00419-x.

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36

Praszałowicz, M., e G. Valencia. "Quark models and chiral lagrangians". Nuclear Physics B 341, n. 1 (settembre 1990): 27–49. http://dx.doi.org/10.1016/0550-3213(90)90261-b.

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37

Martin, Stephen P. "Renormalizable top-quark condensate models". Physical Review D 45, n. 11 (1 giugno 1992): 4283–93. http://dx.doi.org/10.1103/physrevd.45.4283.

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38

Horowitz, C. J., e J. Piekarewicz. "Quark models of nuclear matter". Nuclear Physics A 536, n. 3-4 (gennaio 1992): 669–96. http://dx.doi.org/10.1016/0375-9474(92)90118-4.

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39

Malfatti, German, Milva Orsaria, Gustavo A. Contrera e Fridolin Weber. "Quark-hadron Phase Transition in Proto-Neutron Stars Cores Based on a Non-local NJL Model". International Journal of Modern Physics: Conference Series 45 (gennaio 2017): 1760039. http://dx.doi.org/10.1142/s2010194517600394.

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Abstract (sommario):

We study the QCD phase diagram using a non-local SU(3) NJL model with vector interactions among quarks. We analyze several thermodynamic quantities such as entropy and specific heat, and study the influence of vector interactions on the thermodynamic properties of quark matter. Upon imposing electric charge neutrality and baryon number conservation on the field equations, we compute models for the equation of state of the inner cores of proto-neutron stars by providing a non-local treatment of quark matter for astrophysics.

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40

BERDNIKOV, E. B., e G. P. PRON'KO. "THE RELATIVISTIC MODEL OF THE ORBITAL EXCITATIONS OF HADRONS". International Journal of Modern Physics A 07, n. 14 (10 giugno 1992): 3311–37. http://dx.doi.org/10.1142/s0217751x92001472.

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Abstract (sommario):

The relativistic model describing orbital excitations of hadrons composed of light quarks is considered. All the hadrons are treated in a uniform way as the states of a straight-line string with spinors at its ends. There are a quark and antiquark at the ends in the case of mesons, and a quark and diquark for baryons. The model has an additional symmetry, which allows one to describe the exact LS degeneracy. Although the model proposed is essentially relativistic, the states of its spectrum are classified as in nonrelativistic potential models. The spectrum consists of the family of trajectories arising from splitting the leading Regge trajectory due to the spin of quarks.

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41

MILLER, GERALD A., e JOHN ARRINGTON. "THE INCLUSIVE–EXCLUSIVE CONNECTION AND THE NEUTRON NEGATIVE CENTRAL CHARGE DENSITY". International Journal of Modern Physics E 18, n. 09 (ottobre 2009): 1809–24. http://dx.doi.org/10.1142/s0218301309013877.

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Abstract (sommario):

We find an interpretation of the recent finding that the central charge density of the neutron is negative by using models of generalized parton distributions at zero skewness to relate the behavior of deep inelastic scattering quark distributions, evaluated at high x, to the transverse charge density evaluated at small distances. The key physical input of these models is the Drell–Yan–West relation We find that the d quarks dominate the neutron structure function for large values of Bjorken x, where the large longitudinal momentum of the struck quark has a significant impact on determining the center-of-momentum of the system, and thus the "center" of the nucleon in the transverse position plane.

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42

Brekke, L. "Baryon Magnetic Moments in Quark Models with Anomalous Quark Moments". Annals of Physics 240, n. 2 (giugno 1995): 400–431. http://dx.doi.org/10.1006/aphy.1995.1050.

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43

HAN, XIAO-FANG, LEI WANG e FENG ZHANG. "AN ALTERNATIVE IMPLEMENTATION OF T-PARITY IN FERMION SECTOR AND THE CHANNEL $VV\to h\to\tau\bar{\tau}$ AT LHC". Modern Physics Letters A 26, n. 27 (7 settembre 2011): 2079–89. http://dx.doi.org/10.1142/s0217732311036322.

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Abstract (sommario):

We modify the implementation of T-parity in the fermion sector (called LHT-III), where the mixing of top quark and T-even partner can be absent, and the Higgs mass quadratic divergence contributed by the top quark and a T-odd partner cancel each other. Besides, the Yukawa couplings of down-type quarks and leptons can be enhanced in this model, while these couplings are suppressed in other little Higgs models. Finally, we study the channel [Formula: see text] at LHC in several typical little Higgs models, and find that the rate in all these little Higgs models can have a sizable deviation from the SM prediction, especially for that the rate can only be enhanced in LHT-III, but suppressed in other little Higgs models. Therefore, the Higgs production process [Formula: see text] at LHC can provide a powerful way to probe these little Higgs models, especially for distinguishing the LHT-III from other little Higgs models.

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44

Broniowski, Wojciech, e Bojan Golli. "Approximating chiral quark models with linear σ-models". Nuclear Physics A 714, n. 3-4 (febbraio 2003): 575–88. http://dx.doi.org/10.1016/s0375-9474(02)01377-5.

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45

Celenza, L. S., C. M. Shakin, Wei-Dong Sun, J. Szweda e Xiquan Zhu. "Vertex functions for confined quarks in momentum-space quark-hadron models". Physical Review D 51, n. 7 (1 aprile 1995): 3638–51. http://dx.doi.org/10.1103/physrevd.51.3638.

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46

Çetinkaya, V., V. Arı e O. Çakır. "Effects of the FCNC Couplings in Production of New Heavy Quarks withinZ′Models at the LHC". Advances in High Energy Physics 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/1760219.

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Abstract (sommario):

We study the flavor changing neutral current couplings of new heavy quarks through theZ′models at the LHC. We calculate the cross sections for the signal and the corresponding standard model background processes. Considering the present limits on the mass of new heavy quarks and theZ′boson, we performed an analysis to investigate the parameter space (mixing and mass) through differentZ′models. For FCNC mixing parameterx=0.1and theZ′massMZ′=2000 GeV and new heavy quark massmt′=700 GeV at the LHC withs=13 TeV, we find the cross section for single production of new heavy quarks associated with top quarks as5.8 fb,3.3 fb,1.5 fb, and1.2 fb within theZη′,Zψ′,ZLP′, andZχ′models, respectively. It is shown that the sensitivity would benefit from the flavor tagging.

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47

LAVOURA, LUÍS, e ERNEST MA. "TWO PREDICTIVE SUPERSYMMETRIC S3×Z2 MODELS FOR THE QUARK MASS MATRICES". Modern Physics Letters A 20, n. 16 (30 maggio 2005): 1217–25. http://dx.doi.org/10.1142/s0217732305017561.

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Abstract (sommario):

We propose two simple models for the quark mass matrices which may be implemented through an S3×Z2 symmetry in a supersymmetric context. Each model has eight parameters and, therefore, makes two independent predictions for the quark mixing matrix. The first model predicts [Formula: see text] and [Formula: see text]. The second model, in which the forms of the up-type-quark and down-type-quark mass matrices are interchanged relative to the first one, predicts |Vub/Vcb|~0.11 and |Vtd/Vts|~0.33. Both models have sin 2β~0.5.

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48

Shen, Chengping, e Suxian Li. "Experimental Review of Hadron Spectroscopy". International Journal of Modern Physics: Conference Series 46 (gennaio 2018): 1860005. http://dx.doi.org/10.1142/s2010194518600054.

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Abstract (sommario):

Since the invention of the quark model in 1964 hadrons are formed from a quark-antiquark pair called mesons or three quarks called baryons. However, QCD-motivated models for hadrons predict more complex structures on the hadrons components called generically exotics. These include tetraquark, pentaquark, the six-quark H-dibaryon, hybrid, and glueball mesons. Exotic hadrons have been systematically searched for in many experiments and studied in theories. In the past decade, lots of new hadrons that cannot fit into the normal mesons or baryons were discovered, the so-called [Formula: see text] states. Even so, no unambiguous candidates for any of those exotic configurations have been identified. This review presents an overview of the remarkable progress in the field of exotic hadrons over the past few years.

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49

YUAN, C. P. "STRATEGIES FOR PROBING CP-PROPERTIES IN THE TOP QUARK SYSTEM". Modern Physics Letters A 10, n. 08 (14 marzo 1995): 627–38. http://dx.doi.org/10.1142/s0217732395000673.

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Abstract (sommario):

We discuss strategies for probing CP-properties in the top quark system in electron and hadron collisions. The magnitudes of CP-violation effects predicted by various models are reviewed. The potential of various current and future colliders in measuring the CP-asymmetry associated with the productions and/or decays of the top quarks is also discussed.

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50

Dey, J., M. Dey, G. Mukhopadhaya e B. C. Samanta. "Nucleon and isobar properties in a relativistic Hartree–Fock calculation with vector Richardson potential and various radial forms for scalar mass terms". Canadian Journal of Physics 69, n. 6 (1 giugno 1991): 749–52. http://dx.doi.org/10.1139/p91-125.

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Abstract (sommario):

Mean-field models of the nucleon (N) and the delta (Δ) are established with the two-quark vector Richardson potential along with various prescriptions for a running quark mass (single particle) in the Dirac–Hartree–Fock formalism. The N–Δ splitting is obtained from colour magnetic interaction and the results for gA and the magnetic moment are discussed. An effective density dependent one-body potential U(ρ) for quarks at a given density ρ inside the nucleon is derived. Asymptotic freedom and confinement properties are built-in in U(ρ) and the model dependence is restricted to the intermediate densities.

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