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Ball, Richard D., Alessandro Candido, Juan Cruz-Martinez, Stefano Forte, Tommaso Giani, Felix Hekhorn, Kirill Kudashkin, Giacomo Magni e Juan Rojo. "Evidence for intrinsic charm quarks in the proton". Nature 608, n.º 7923 (17 de agosto de 2022): 483–87. http://dx.doi.org/10.1038/s41586-022-04998-2.
AbstractThe theory of the strong force, quantum chromodynamics, describes the proton in terms of quarks and gluons. The proton is a state of two up quarks and one down quark bound by gluons, but quantum theory predicts that in addition there is an infinite number of quark–antiquark pairs. Both light and heavy quarks, whose mass is respectively smaller or bigger than the mass of the proton, are revealed inside the proton in high-energy collisions. However, it is unclear whether heavy quarks also exist as a part of the proton wavefunction, which is determined by non-perturbative dynamics and accordingly unknown: so-called intrinsic heavy quarks1. It has been argued for a long time that the proton could have a sizable intrinsic component of the lightest heavy quark, the charm quark. Innumerable efforts to establish intrinsic charm in the proton2 have remained inconclusive. Here we provide evidence for intrinsic charm by exploiting a high-precision determination of the quark–gluon content of the nucleon3 based on machine learning and a large experimental dataset. We disentangle the intrinsic charm component from charm–anticharm pairs arising from high-energy radiation4. We establish the existence of intrinsic charm at the 3-standard-deviation level, with a momentum distribution in remarkable agreement with model predictions1,5.We confirm these findings by comparing them to very recent data on Z-boson production with charm jets from the Large Hadron Collider beauty (LHCb) experiment6.
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SHI, X. H., G. L. MA, Y. G. MA, X. Z. CAI e J. H. CHEN. "“TEMPERATURE” FLUCTUATION AND HEAT CAPACITIES OF QUARKS AND π MESON". International Journal of Modern Physics E 16, n.º 07n08 (agosto de 2007): 1912–16. http://dx.doi.org/10.1142/s0218301307007222.
Specific heat capacities of π meson and different quarks after parton cascade AMPT model in Au + Au collisions at [Formula: see text] have been tentatively extracted from the event-by-event temperature fluctuations in the region of low transverse mass. The specific heat capacity of π meson shows a slight dropping trend with increasing impact parameter. The specific heat capacities of different quarks increase with the mass of quark, and the sum of up and down quark's specific heat capacities was found to be approximately equal to that of π meson.
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ANTUNES, ANTONIO CARLOS BAPTISTA, e LEILA JORGE ANTUNES. "DIQUARK FORMATION IN ANGULAR-MOMENTUM-EXCITED BARYONS". International Journal of Modern Physics A 24, n.º 10 (20 de abril de 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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ANTUNES, ANTONIO CARLOS BAPTISTA, e LEILA JORGE ANTUNES. "ABSENCE OF DIQUARKS IN S-WAVE BARYONS". International Journal of Modern Physics A 22, n.º 25 (10 de outubro de 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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Arghirescu, Marius. "A hybrid model of constituent quarks". Physics & Astronomy International Journal 6, n.º 3 (20 de setembro de 2022): 109–17. http://dx.doi.org/10.15406/paij.2022.07.00262.
The paper presents a hybrid model of constituent quark which considers the preonic structure based on z0 (34 me)-preon, specific to the previously published cold genesis theory (CGT) of the author and basic concepts of the S.M. which seem experimentally sustained, explaining the constituent quarks forming from current quarks and “gammonic” gluols –in concordance with the experimentally evidenced possibility of paired quarks forming from relativist jets of negatrons and positrons, by considering that the negatrons and positrons can form ‘gammonic’ “gluols” and thereafter- current and constituent quarks, by the magnetic and electric interactions between the paired quasielectrons (degenerate electrons), which can explain the constituent u- quark’s stability until the critical temperature 2x1012 K, without the concepts of “color charge” and of “virtual” gluon/boson. The resulted hybrid model can also explain why in strong interactions the sum rule can be applied correspondent with the transferring of some quarks from an interacting particle to another with the entire or almost entire their constituent mass. Also, it suggests that the mechanism of paired current u-quarks forming from gluons, used by the S. M., can be plausible in conformity with the mass conservation law only if the quantum vacuum contains real thermalized “gammons” considered as (e+e-)*-pairs of degenerate electrons.
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Bhattacharyya, Trambak, Surasree Mazumder e 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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KAUS, PETER, e SYDNEY MESHKOV. "A BCS QUARK MASS MATRIX". Modern Physics Letters A 03, n.º 13 (outubro de 1988): 1251–59. http://dx.doi.org/10.1142/s0217732388001501.
The quark mass gap and quark mass hierarchy is obtained by introducing a BCS interaction among ur-quarks. A 3×3 quark mass matrix with equal matrix elements, i.e., with all ur-flavors interacting with the same strength, has eigenvalues 0, 0 and 3; both the quark charge −1/3 and charge +2/3 systems with one heavy quark and two almost massless quarks resemble these eigenvalues. The physical mass splittings between the two lightest quarks come from higher-order corrections to the mass matrix which are obtained by fitting the Kobayashi-Maskawa matrix VKM.
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FRITZSCH, H., e G. ELDAHOUMI. "CONSTITUENT QUARKS AND THE SPIN OF THE PROTON". Modern Physics Letters A 24, n.º 27 (7 de setembro de 2009): 2167–74. http://dx.doi.org/10.1142/s0217732309031788.
The constituent quarks are interpreted as bound states, which have an internal structure. The quark distributions of the proton are related to those of the constituent quarks. The experiments support this hypothesis. Likewise the spin structure of the proton is related to the spin structure of the constituent quarks. We find that about 30% of the spin of a constituent quark is given by the valence quark, and 70% are provided by the gluons.
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Battistel, O. A., e G. Krein. "Quark Clustering and Chiral Symmetry Breaking in Nuclear Matter". Modern Physics Letters A 18, n.º 32 (20 de outubro de 2003): 2255–64. http://dx.doi.org/10.1142/s0217732303012040.
Chiral symmetry breaking at finite baryon density is usually discussed in the context of quark matter, i.e. a system of deconfined quarks. Many systems like stable nuclei and neutron stars however have quarks confined within nucleons. In this paper we construct a Fermi sea of three-quark nucleon clusters and investigate the change of the quark condensate as a function of baryon density. We study the effect of quark clustering on the in-medium quark condensate and compare results with the traditional approach of modeling hadronic matter in terms of a Fermi sea of deconfined quarks.
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STROBEL, GEORGE L. "BARYON MAGNETIC MOMENTS AND SPIN DEPENDENT QUARK FORCES". International Journal of Modern Physics E 11, n.º 01 (fevereiro de 2002): 71–81. http://dx.doi.org/10.1142/s0218301302000697.
The J=3/2 Δ, J=1/2 nucleon mass difference shows that quark energies can be spin dependent. It is natural to expect that quark wave functions also depend on spin. In the octet, such spin dependent forces lead to different wave functions for quarks with spin parallel or antiparallel to the nucleon spin. A two component Dirac equation wave function is used for the quarks assuming small current quark masses for the u and d quarks. Then, the neutron/proton magnetic moment ratio, the nucleon axial charge, and the spin content of the nucleon can all be simultaneously fit assuming isospin invariance between the u and d quarks, but allowing for spin dependent forces. The breakdown of the Coleman–Glashow sum rule for octet magnetic moments follows naturally in this Dirac approach as the bound quark energy also effects the magnetic moment. Empirically the bound quark energy increases with the number of strange quarks in the system. Allowing the strange quark wave function similar spin dependence predicts the magnetic moments of the octet, in close agreement with experiment. Differences between the octet and decuplet magnetic moments are also explained immediately with spin dependent wave functions.
Caron, Huot Simon 1984. "Heavy quark energy losses in the quark-gluon plasma : beyond leading order". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112385.
We compute, to next-to-leading order in perturbation theory, the rate of energy loss suffered by a heavy quark moving nonrelativistically in the quark-gluon plasma. This quantity is essentially a measure of the scattering rates of this quark against plasma constituents, and of their efficiency in slowing it down. The next-to-leading order correction is sensitive to the physics of overlapping scatterings, as well as to the self-interactions of gauge fields with small momenta (of order the electric screening scale). We find the next-to-leading order correction to be remarkably large, suggesting that the perturbative series is unreliable unless the coupling constant of the theory assumes unrealistically small values.
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BASTOS, Cristiano Costa. "Química com quarks". Universidade Federal de Pernambuco, 2007. https://repositorio.ufpe.br/handle/123456789/8777.
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Previous issue date: 2007 Algumas propriedades da química de quarks podem ser obtidas realizando cálculos ab initio Hartree-Fock para átomos com carga nuclear fracionária e moléculas formadas por estes átomos.
Obtivemos o estado fundamental e o primeiro estado excitado para os átomos de sódio, lítio, berílio e magnésio interagentes com quarks. Isto sugere que transições eletrônicas podem ser usadas como guia para detecção de quarks livres.
Analisamos a variação da energia de ligação eletrônica com a carga nuclear para as séries isoeletrônicas de átomos com carga nuclear fracionária A±2/3 e A±1/3 (A = H, Li, Na, P and Ca). Isto mostra que partículas de cor não confinadas preferem se ligar a átomos pesados e o par quark-antiquark pode ser estabilizado na presença da matéria atômica
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Wünsch, Rudi, e Mathias Schleif. "The Chiral Quark-Loop Soliton in a Hot Gas of Constituent Quarks". Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-31115.
We consider a chiral one-loop hedgehog soliton of the bosonized SU(2)f Nambu & Jona-Lasinio model which is embedded in a liot medium of constituent quarks. Energy and radius of the soliton are determined in self-consistent mean-field approximation. Quasi-classical corrections to the soliton energy are derived by means of the pushing and cranking approaches. The corresponding inertial parameters are evaluated. It is shown that the inertial mass is equivalent to the total internal energy of the soliton. Corrected nucleon and ∆ isobar masses are calculated in dependence on temperature and density of the medium. As a result of the internal structure of the soliton which is controlled by the self-consistent mean field, the scaling between constituent quark mass and soliton mass is noticeable disturbed.
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Wünsch, Rudi, e Mathias Schleif. "The Chiral Quark-Loop Soliton in a Hot Gas of Constituent Quarks". Forschungszentrum Rossendorf, 1997. https://hzdr.qucosa.de/id/qucosa%3A21938.
We consider a chiral one-loop hedgehog soliton of the bosonized SU(2)f Nambu & Jona-Lasinio model which is embedded in a liot medium of constituent quarks. Energy and radius of the soliton are determined in self-consistent mean-field approximation. Quasi-classical corrections to the soliton energy are derived by means of the pushing and cranking approaches. The corresponding inertial parameters are evaluated. It is shown that the inertial mass is equivalent to the total internal energy of the soliton. Corrected nucleon and ∆ isobar masses are calculated in dependence on temperature and density of the medium. As a result of the internal structure of the soliton which is controlled by the self-consistent mean field, the scaling between constituent quark mass and soliton mass is noticeable disturbed.
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Smith, Jason. "Quarks and antiquarks in nuclei /". Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9750.
Julien, Jean Marc. "Structure du noyau, particules élémentaires : Les quarks : ultimes entités de la matière". Paris 5, 1988. http://www.theses.fr/1988PA05P060.
Spiering, Christian. "Quarks". In Auf der Suche nach der Urkraft, 39–45. Wiesbaden: Vieweg+Teubner Verlag, 1986. http://dx.doi.org/10.1007/978-3-322-86648-6_8.
Fritzsch, Harald. "Quarks". In Murray Gell-Mann and the Physics of Quarks, 49–51. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-92195-2_5.
Schaeffer, Johannes. "Quarks". In SU(n), Darstellungstheorie und deren Anwendung im Quarkmodell, 75–84. Wiesbaden: Springer Fachmedien Wiesbaden, 2021. http://dx.doi.org/10.1007/978-3-658-36073-3_5.
Albright, John R. "Quarks". In Encyclopedia of Sciences and Religions, 1939. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-1-4020-8265-8_200850.
Lang, Christian B., e Leopold Mathelitsch. "Quarks". In Haben Sie eines gesehen?, 189–205. Berlin, Heidelberg: Springer Berlin Heidelberg, 2023. http://dx.doi.org/10.1007/978-3-662-67972-2_11.
Brambilla, Nora. "Quark Nuclear Physics with Heavy Quarks". In Handbook of Nuclear Physics, 1–43. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-15-8818-1_26-1.
Brambilla, Nora. "Quark Nuclear Physics with Heavy Quarks". In Handbook of Nuclear Physics, 2963–3005. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-6345-2_26.
Trabalhos de conferências sobre o assunto "Quarks":
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Soto, Joan. "Heavy Quarks". In QUARK CONFINEMENT AND THE HADRON SPECTRUM VI: 6th Conference on Quark Confinement and the Hadron Spectrum - QCHS 2004. AIP, 2005. http://dx.doi.org/10.1063/1.1920949.
Grigoriev, D. Yu, V. A. Matveev, V. A. Rubakov e P. G. Tinyakov. "Quarks '92". In 7th International Seminar. WORLD SCIENTIFIC, 1993. http://dx.doi.org/10.1142/9789814535687.
"Concrete Quarks". In International School of Subnuclear Physics, ISSP 2014, 52nd Course, editado por George Zweig. World Scientific, 2016. http://dx.doi.org/10.1142/9789813148680_0002.
Tseng, Jeffrey. "Searches for vector-like quarks with top quarks". In 8th International Workshop on Top Quark Physics. Trieste, Italy: Sissa Medialab, 2016. http://dx.doi.org/10.22323/1.257.0046.
Kitazawa, Masakiyo. "Spectral Properties of Quarks in the Quark-Gluon Plasma". In The XXV International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2008. http://dx.doi.org/10.22323/1.042.0197.
Bürger, W., M. Faber, H. Markum e M. Müller. "Quark multiplet potentials with dynamical quarks on the lattice". In Intersections between particle and nuclear physics. AIP, 1992. http://dx.doi.org/10.1063/1.41603.
Parappilly, Maria B. "Effects of dynamical sea-quarks on quark and gluon propagators". In PARTICLES AND NUCLEI: Seventeenth Internatinal Conference on Particles and Nuclei. AIP, 2006. http://dx.doi.org/10.1063/1.2220236.
ZAKHAROV, V., O. EVDOKIMOV, S. KABANA, K. KOTOV, S. SADOVSKY e S. TROSHIN. "PANEL DISCUSSION II: QUARK-GLUON PLASMA, HEAVY QUARKS AND EXOTICS". In XXIXth International Workshop on High Energy Physics. WORLD SCIENTIFIC, 2014. http://dx.doi.org/10.1142/9789814578745_0010.
Takeda, K. "Calculation of nucleon strange quark content with dynamical overlap quarks". In The XXVII International Symposium on Lattice Field Theory. Trieste, Italy: Sissa Medialab, 2010. http://dx.doi.org/10.22323/1.091.0141.
Relatórios de organizações sobre o assunto "Quarks":
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Weinstein, Marvin. Quarks, Gluons and Frustrated Antiferromagnets. Office of Scientific and Technical Information (OSTI), outubro de 1999. http://dx.doi.org/10.2172/15073.
Lavoura, L., e J. P. Silva. Bounds on the mixing of the down-type quarks with vector-like singlet quarks. Office of Scientific and Technical Information (OSTI), setembro de 1992. http://dx.doi.org/10.2172/10188401.
Lavoura, L., e J. P. Silva. Bounds on the mixing of the down-type quarks with vector-like singlet quarks. Office of Scientific and Technical Information (OSTI), setembro de 1992. http://dx.doi.org/10.2172/6949791.
Dziembowski, Z. Segregation of quarks within the neutron. Office of Scientific and Technical Information (OSTI), dezembro de 1991. http://dx.doi.org/10.2172/10107263.
White, A. R. Light quarks and small X physics. Office of Scientific and Technical Information (OSTI), junho de 1992. http://dx.doi.org/10.2172/10141975.
Dziembowski, Z. Segregation of quarks within the neutron. Office of Scientific and Technical Information (OSTI), janeiro de 1991. http://dx.doi.org/10.2172/6091708.
Peters, Reinhild Yvonne. Measurements and searches with top quarks. Office of Scientific and Technical Information (OSTI), agosto de 2008. http://dx.doi.org/10.2172/945431.
Lewandowski, Bernd. SPECTROSCOPY OF HEAVY QUARKS AT BABAR. Office of Scientific and Technical Information (OSTI), agosto de 2003. http://dx.doi.org/10.2172/815302.
Bellodi, Giulia. Electroweak Measurements with Heavy Quarks at SLD. Office of Scientific and Technical Information (OSTI), outubro de 2000. http://dx.doi.org/10.2172/784724.
Becher, Thomas G. The Self-Energy of Improved Staggered Quarks. Office of Scientific and Technical Information (OSTI), fevereiro de 2003. http://dx.doi.org/10.2172/812639.
