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ANTUNES, ANTONIO CARLOS BAPTISTA, and LEILA JORGE ANTUNES. "ABSENCE OF DIQUARKS IN S-WAVE BARYONS." International Journal of Modern Physics A 22, no. 25 (October 10, 2007): 4709–16. http://dx.doi.org/10.1142/s0217751x07037950.
We analyze the dynamics of diquark formation in baryons containing one light and two heavy quarks. Due to the slower motion of the heavy quarks, we consider the motion of the light quark in a reference frame fixed in the two heavy ones. The potential of the light quark interacting with the two heavy quarks is derived from the quark–antiquark potential in mesons. This potential has a repulsive barrier between the two heavy quarks. A variational approach similar to that used in the study of the hydrogen molecule is applied to determine the two lowest energy eigenvalues and eigenfunctions of the light quark. The time-dependent wave function obtained describes the oscillation of the light quark along the direction defined by the two heavy quarks. We observe that the energy of this oscillating state is higher than the repulsive barrier between the two heavy quarks. There is no tunneling in the oscillation of the light quark, so we conclude that there is not formation of clusters or metastable states of a heavy and a light quark in this kind of baryons.
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ANTUNES, ANTONIO CARLOS BAPTISTA, and LEILA JORGE ANTUNES. "DIQUARK FORMATION IN ANGULAR-MOMENTUM-EXCITED BARYONS." International Journal of Modern Physics A 24, no. 10 (April 20, 2009): 1987–94. http://dx.doi.org/10.1142/s0217751x09043249.
Diquarks, or metastable clusters of two quarks inside baryons, are shown to be produced by angular momentum excitation. In baryons with a light quark and two heavy quarks with large angular momentum (L>2), the centrifugal barrier that appears in the rotation frame of the two heavy quarks prevents the light quark from passing freely between the two heavy quarks. The light quark must tunnelize through this potential barrier, which gives rise to the clusters of a light and a heavy quark.
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Gomes, Frederico F., Bruna C. Folador, Dimiter Hadjimichef, and Daniel T. da Silva. "A Heavy-Light Quark Potential." International Journal of Modern Physics: Conference Series 45 (January 2017): 1760054. http://dx.doi.org/10.1142/s2010194517600540.
In many studies of meson-baryon interactions with short one gluon exchange potential (OGEP), usually a full non-relativistic reduction, at the quark level Hamiltonian, is performed. In systems like [Formula: see text], light and heavy quarks are present, which in principle would require only a partial non-relativistic reduction. We shal start from a JKJ relativistic quark Hamiltonian and apply a partial non-relativistic reduction in order to obtain a OGEP between heavy and light quarks (heavy-light quark potential).
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Afonin, S. S., and I. V. Pusenkov. "Note on universal description of heavy and light mesons." Modern Physics Letters A 29, no. 35 (November 17, 2014): 1450193. http://dx.doi.org/10.1142/s0217732314501934.
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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AVILA, M. A. "LIGHT QUARK ORBITAL RADIUS OF A HEAVY QUARK–LIGHT QUARK SYSTEM IN AN S-STATE." Modern Physics Letters A 14, no. 02 (January 20, 1999): 113–24. http://dx.doi.org/10.1142/s0217732399000158.
Radial probability density function of a heavy quark–light quark [Formula: see text] system in an S-state is analyzed numerically. It is found that the maximum of this function at r=a0 and the light quark energy (Eq) are related through the relation Eq=Z/a0, where Z=c0/c, c is the strength of the color Coulomb potential and c0=0.446. Z<1 can be thought of as due to a color anti-screening effect. The respective expectation value for r in this state is [Formula: see text]. These results are valid for c in the range c0≤ c≤0.7 and a light quark mass in the range 0≤ m≤ 300 MeV. As a result of these patterns of regularity, bounds on the mass of the heavy quarks are imposed. These give mc=1.3±0.33 GeV and mb=4.6±0.3 GeV. It is also shown that Eq is not directly an "inertia" parameter, as it has been called by the heavy quark effective theory, but a physical quantity that needs to be measured. The relations found in the present work coincide with the maximum value that the slope of the Isgur–Wise function at zero recoil can take, in either way [Formula: see text] or [Formula: see text].
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BEDNYAKOV, V. A. "ON LEADING CHARMED MESON PRODUCTION IN π–NUCLEON INTERACTIONS". Modern Physics Letters A 10, № 01 (10 січня 1995): 61–65. http://dx.doi.org/10.1142/s0217732395000077.
It is shown that the D-meson, whose light quark is the initial-pion valence quark and whose charmed quark is produced in annihilation of valence quarks and has got a large enough momentum, is really a leading meson in reactions like π−p → DX. If such annihilation of valence quarks from initial hadrons is impossible there must be no distinct leading effect.
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Bhattacharyya, Trambak, Surasree Mazumder, and Raktim Abir. "Soft Gluon Radiation off Heavy Quarks beyond Eikonal Approximation." Advances in High Energy Physics 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/1298986.
We calculate the soft gluon radiation spectrum off heavy quarks (HQs) interacting with light quarks (LQs) beyond small angle scattering (eikonality) approximation and thus generalize the dead-cone formula of heavy quarks extensively used in the literatures of Quark-Gluon Plasma (QGP) phenomenology to the large scattering angle regime which may be important in the energy loss of energetic heavy quarks in the deconfined Quark-Gluon Plasma medium. In the proper limits, we reproduce all the relevant existing formulae for the gluon radiation distribution off energetic quarks, heavy or light, used in the QGP phenomenology.
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Kaur, Satvir, and Harleen Dahiya. "Study of Spin–Spin Correlations between Quark and a Spin-1/2 Composite System." Advances in High Energy Physics 2020 (January 27, 2020): 1–13. http://dx.doi.org/10.1155/2020/9429631.
We study the correlation between the fermion composite system and quark spins by using the light-cone quark–diquark model. We do the calculations for u-quark and d-quark in the fermion system by considering different polarization configurations of both. The contribution from scalar and axial-vector diquarks is taken into account. The overlap representation of light-front wavefunctions is used for the calculations. The spin–spin correlations for u and d quarks are presented in transverse impact-parameter plane and transverse momentum plane as well.
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MAO, YAXIAN, WENCHANG XIANG, and DAICUI ZHOU. "CHARM QUARK ENERGY LOSS IN DENSE MATTER WITHIN THE LIGHT-CONE PATH INTEGRAL APPROACH." International Journal of Modern Physics E 16, no. 07n08 (August 2007): 2130–36. http://dx.doi.org/10.1142/s021830130700757x.
The energy loss of heavy quarks traversing color dense matter is calculated with an analytical formula derived within the light-cone path integral (LCPI) approach. We find that the energy loss mechanism is dominated by gluon radiation and induces a suppression pattern of charm quark different from the suppression of light quarks. We find also that this radiative energy-loss is proportional to L2 for energetic quarks, but changes to a L dependance with decreasing quark energy, where L is the length of the traversed medium.
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Kopeliovich, Boris, Jan Nemchik, Irina Potashnikova, and Ivan Schmidt. "Unconventional Mechanisms of Heavy Quark Fragmentation." Universe 9, no. 9 (September 13, 2023): 418. http://dx.doi.org/10.3390/universe9090418.
Heavy and light quarks produced in high-pT partonic collisions radiate differently. Heavy quarks regenerate their color field, stripped-off in the hard reaction, much faster than the light ones and radiate a significantly smaller fraction of the initial quark energy. This peculiar feature of heavy-quark jets leads to a specific shape of the fragmentation functions observed in e+e− annihilation. Differently from light flavors, the heavy quark fragmentation function strongly peaks at large fractional momentum z, i.e., the produced heavy–light mesons, B or D, carry the main fraction of the jet momentum. This is a clear evidence of the dead-cone effect, and of a short production time of a heavy–light mesons. Contrary to propagation of a small qq¯ dipole, which survives in the medium due to color transparency, a heavy–light Qq¯ dipole promptly expands to a large size. Such a big dipole has no chance to remain intact in a dense medium produced in relativistic heavy ion collisions. On the other hand, a breakup of such a dipole does not affect much the production rate of Qq¯ mesons, differently from the case of light qq¯ meson production.
Fariborz, A. H. "Investigations in light-quark low-energy quantum chromodynamics." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq28486.pdf.
Souchlas, Nicholas. "Quark Dynamics and Constituent Masses in Heavy Quark Systems." Kent State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1248013809.
Due to quark-gluon confinement in QCD, the quark masses entering the QCD Lagrangian cannot be measured with the same techniques one would use to determine the mass of non-confined particles. They must be determined either numerically from Lattice QCD, or analytically using QCD sum rules. The latter makes use of the complex squared energy plane, and Cauchy’s theorem for the correlator of axial-vector divergences. This procedure relates a QCD expression containing the quark masses, with an hadronic expression in terms of known hadron masses, couplings, and lifetimes/widths. Thus, the quark masses become a function of known hadronic information. In this dissertation, the light quark masses are determined from a QCD finite energy sum rule, using the pseudoscalar correlator to six-loop order in perturbative QCD, with the leading vacuum condensates and higher order quark mass corrections included. The systematic uncertainties stemming from the hadronic resonance sector are reduced, by introducing an integration kernel in the Cauchy integral in the complex squared energy plane. Additionally, the issue of convergence of the perturbative QCD expression for the pseudoscalar correlator is examined. Both the fixed order perturbation theory (FOPT) method and contour improved perturbation theory (CIPT) method are explored. Our results from the latter exhibit good convergence and stability in the window s0 = 3.0 − 5.0 GeV2 for the strange quark and s0 = 1.5 − 4.0 GeV2 for the up and down quarks; where s0 is the radius of the integration contour in the complex s-plane. The results are: ms(2 GeV) = 91.8 ± 9.9 MeV, mu(2 GeV) = 2.6 ± 0.4 MeV, md(2 GeV) = 5.3 ± 0.4 MeV, and the sum mud ≡ (mu + md)/2, is mud(2 GeV) = 3.9 ± 0.3 MeV. They compare favourably to the PDG and FLAG world averages. Further in this dissertation the updated series expansion of the quark mass renormalization group equation (RGE) to five-loop order is derived. The series provides the relation between a light quark mass in the modified minimal subtraction (MS) scheme defined at some given scale, e.g. at the tau-lepton mass scale, and another chosen energy scale, s. This relation explicitly depicts the renormalization scheme dependence of the running quark mass on the scale parameter, s, and is important in accurately determining a light quark mass at a chosen scale. The five-loop QCD β(as) and γ(as) functions are used in this determination.
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Nelson, Daniel Richard. "Partially Quenched Chiral Perturbation Theory and a Massless Up Quark: A Lattice Calculation of the Light-Quark-Mass Ratio." Connect to this title online, 2002. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1038343149.
Thesis (Ph. D.)--Ohio State University, 2002. Title from first page of PDF file. Document formatted into pages; contains xxiii, 296 p.; also includes graphics (some col.) Includes bibliographical references (p. 293-296). Available online via OhioLINK's ETD Center
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Samways, Benjamin. "A lattice measurement of the B*Bπ coupling using DWF light quarks and the relativistic heavy quark action". Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/361526/.
I describe a calculation of the B*Bπ coupling in lattice QCD. The B*Bπ coupling is directly related to gb, the leading order low-energy interaction constant of heavy meson chiral perturbation theory. Knowledge of the coupling will help decrease systematic uncertainties in lattice QCD B-physics studies, which are important to constrain the CKM matrix and probe the Standard Model. This calculation is performed with 2+1 flavours of dynamic quarks using the domain wall fermion action. To simulate the heavy b-quark I use a non-perturbatively tuned relativistic heavy quark action which keeps discretisation effects under good control. This allows me to make the first calculation of the B*Bπ coupling directly at the physical b-quark mass. I conduct a chiral and continuum extrapolation to the physical point and consider all sources of systematic error. The final result including both statistical and sytematic errors is gb = 0.567(52)stat(58)sys.
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Williams, Jimmy. "Two-loop renormalization of the quark propagator in the light-cone gauge." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0002/NQ43279.pdf.
DeWitt, Martin Alan. "The Spectrum and Decays of Scalar Mesons in the Light-Front Quark Model." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-03282008-142316/.
We use the light-front quark model to investigate the structure of the scalar mesons, mainly focusing on the three heavy isoscalar states f0(1370), f0(1500), and f0(1710). We comput the spectrum of scalar mesons by diagonalizing a relativized, QCD-inspired model Hamiltonian written in a basis of 25 simple harmonic oscillator states. The masses are then used to perform a mixing analysis which assumes that the heavy isoscalars are mixtures of quarkonia and the scalar glueball. The resulting quark-glue content is used along with the meson wave functions determined from the spectrum to compute the decay rates to pairs of pseudoscalar mesons (two pions, two kaons, two eta mesons). We find that when the glueball contributions to the decays are ignored, the results are in poor agreement with the available data. However, when we estimate the effect of including the glueball contributions in the decays, a solution can be found that matches the data quite well. In this solution, the f0(1710) is mostly glueball (78%) while the f0(1500) and f0(1370) are mostly mixtures of quarkonia. Additionally, in this solution the glueball contributions to kaon and eta final states are significant, while the contributions to the pion final state is negligible. This finding is in agreement with Chanowitz who uses chiral perturbation theory to show that the amplitude for a scalar glueball to decay to a quark-antiquark pair is proportional to the quark mass. This results in a suppression of the pion decay channel compared to the kaon and eta decay channels.
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Arndt, Daniel. "Light-Cone Quark Model Analysis ofPseudoscalar and Vector Mesons for Radially Excited States." NCSU, 1999. http://www.lib.ncsu.edu/theses/available/etd-19990518-132243.
We present a relativistic constituent quark model to analyze the mass spectrum and hadronic properties of radially excited u and d quark sector mesons.Using a simple Gaussian function as a trial wave function for the variational principle togetherwith a QCD motivated Hamiltonian, including not only the Coulomb and confiningpotential but also a relativistic corrected hyperfine interaction term, we obtain the mass spectrum consistent with the experimental data. To do the same for several observables such as decay constants and form factors it seems necessary to include bothDirac and Pauli form factors on the level of constituentquarks. Taking into account these quark form factorswe thus present the generalized formulas for the rho mesondecay constant and the rho meson form factors as well asthe $\pi\gamma$ transition form factor.We alsopredict several hadronic properties for the radiallyexcited states.
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Arndt, Daniel. "Light-cone quark model analysis of pseudoscalar and vector mesons for radially excited states." Raleigh, NC : North Carolina State University, 1999. http://www.lib.ncsu.edu/etd/public/etd-3522131849921371/etd.pdf.
Workshop, on Light Quark Meson Spectroscopy (3rd 1992 Tsukuba-shi Japan). Proceedings of the Third Workshop on Light Quark Meson Spectroscopy: February 28-29, 1992, KEK, Tsukuba, Japan. Tsukuba-shi, Ibaraki-ken, Japan: National Laboratory for High Energy Physics, 1992.
Gastaldi, Ugo, Robert Klapisch, and Frank Close, eds. Spectroscopy of Light and Heavy Quarks. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4613-0763-1.
International School of Physics with Low Energy Antiprotons on Spectroscopy of Light and Heavy Quarks (2nd 1987 Erice, Italy). Spectroscopy of light and heavy quarks. New York: Plenum Press, 1989.
EPIC 2000 (2000 Cambridge, Mass.). Physics with an electron polarized light-ion collider: Second Workshop EPIC 2000, Cambridge, Massachusetts, 14-15 September 2000. Edited by Milner Richard Gerard. Melville, N.Y: AIP, 2001.
Amsler, Claude. "Light Baryon Excitations." In The Quark Structure of Hadrons, 183–92. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-98527-5_15.
Roberts, Craig D. "Unifying Aspects of Light- and Heavy-Systems." In Heavy Quark Physics, 149–88. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-40975-5_6.
Burkhardt, H. "Uncertainties from light quark loops." In Radiative Corrections for e+e- Collisions, 75–82. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-74925-4_4.
Ratti, Sergio P. "Light Quark Photoproduction at Fermilab." In International Europhysics Conference on High Energy Physics, 359–62. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-59982-8_30.
Fischer, H. G. "Transverse momentum systematics in proton-proton and light ion collisions at the ISR." In Quark Matter, 105–8. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-83524-7_14.
ZAITSEV, A. "LIGHT QUARK SPECTROSCOPY." In Proceedings of the 33rd International Conference. World Scientific Publishing Company, 2007. http://dx.doi.org/10.1142/9789812790873_0009.
Nakamura, Yoshifumi. "Simulating at realistic quark masses: light quark masses." In XXIVth International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2006. http://dx.doi.org/10.22323/1.032.0160.
Ivanov, M. A., and T. Mizutani. "Heavy quark limit in the model with confined light quarks and infrared heavy quark propagators." In The 14th international conference of few-body problems in physics. AIP, 1995. http://dx.doi.org/10.1063/1.48164.
EWERZ, C. "GRIBOV'S LIGHT QUARK CONFINEMENT SCENARIO." In Proceedings of the 5th International Conference. WORLD SCIENTIFIC, 2003. http://dx.doi.org/10.1142/9789812704269_0046.
Donnachie, A. "Light-Quark Vector-Meson Spectroscopy." In HADRON SPECTROSCOPY: Ninth International Conference on Hadron Spectroscopy. AIP, 2002. http://dx.doi.org/10.1063/1.1482431.
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Wallner, Stefan. "Light-Quark Resonances at COMPASS." In XIII Quark Confinement and the Hadron Spectrum. Trieste, Italy: Sissa Medialab, 2019. http://dx.doi.org/10.22323/1.336.0097.
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Kalelkar, Mohan S. Identified Hadron Production and Light Quark Fragmentation in Z{sup 0} Decays. Office of Scientific and Technical Information (OSTI), October 1998. http://dx.doi.org/10.2172/9941.
Milstene, C., Marcela S. Carena, A. Freitas, A. Finch, A. Sopczak, and Hannelies Kluge. The light stop quark with small stop-neutralino difference in the MSSM. Office of Scientific and Technical Information (OSTI), December 2005. http://dx.doi.org/10.2172/879117.
Staengle, Hermann. Light Quark Fragmentation and a Measurement of A{sub s} at the SLD. Office of Scientific and Technical Information (OSTI), April 1999. http://dx.doi.org/10.2172/10210.
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Tadepalli, Arun S. Light Anti-Quark Flavor Asymmetry in the Nucleon Sea and the Nuclear Dependence of Anit-Quarks in Nuclei at the Seaquest Experiment. Office of Scientific and Technical Information (OSTI), January 2019. http://dx.doi.org/10.2172/1574838.
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