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Artículos de revistas sobre el tema "B mesons Quantum chromodynamics"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 8 de febrero de 2022

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1

Kim, D. Y. y S. N. Sinha. "Remarks on broken chiral SU(5) × SU(5) symmetry and B mesons". Canadian Journal of Physics 63, n.º 10 (1 de octubre de 1985): 1294–98. http://dx.doi.org/10.1139/p85-213.

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In a recent paper, Hatzis has estimated the masses and weak decay constants of b-flavored pseudoscalar mesons in a broken chiral SU(5) × SU(5) symmetry method. The estimated weak decay constant of B meson, [Formula: see text], however, does not agree with the value [Formula: see text] evaluated by Mathur et al. with the quantum chromodynamics (QCD) sum-rule model. We re-examined the problem applying the broken chiral SU(5) × SU(5) symmetry approach using a set of mass formulae. With this method we estimate the symmetry-breaking parameters and decay constants of pseudoscalar mesons. We found a consistent result for the decay constant: [Formula: see text]. The explicit numerical value of these constants, however, are lower than that of the QCD sum rule. This may be due to the limited validity of the broken chiral symmetry approach for heavy mesons.

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2

Talebtash, Mohammad Rahim y Hossein Mehraban. "Final state interaction effect in the pure annihilation B→ϕϕ decay". Canadian Journal of Physics 93, n.º 11 (noviembre de 2015): 1235–39. http://dx.doi.org/10.1139/cjp-2014-0472.

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We analyzed the process of [Formula: see text] decay in quantum chromodynamics factorization (QCDF) and final state interaction (FSI). In QCDF for this decay we have only the annihilation graph and we expected small branching ratio. Then we considered FSI effect as a sizable correction where the intermediate states are [Formula: see text], K+ K–, and [Formula: see text] mesons. To consider the amplitudes of these intermediate states, the QCDF approach was used. The experimental branching ratio of [Formula: see text] is less than 2 × 10–7 and our results are 0.04 × 10–7 and 1.54 × 10–7 from QCDF and FSI, respectively.

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3

Karpishkov, A. V., M. A. Nefedov, V. A. Saleev y A. V. Shipilova. "B-meson production at Tevatron and the LHC in the Regge limit of quantum chromodynamics". Physics of Atomic Nuclei 79, n.º 2 (marzo de 2016): 275–77. http://dx.doi.org/10.1134/s1063778816020095.

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4

Yu, Gong-Ming, Gao-Gao Zhao, Zhen Bai, Yan-Bing Cai, Hai-Tao Yang y Jian-Song Wang. "ηQ Meson Photoproduction in Ultrarelativistic Heavy Ion Collisions". Advances in High Energy Physics 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/2379319.

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The transverse momentum distributions for inclusive ηc,b meson described by gluon-gluon interactions from photoproduction processes in relativistic heavy ion collisions are calculated. We considered the color-singlet (CS) and color-octet (CO) components within the framework of Nonrelativistic Quantum Chromodynamics (NRQCD) in the production of heavy quarkonium. The phenomenological values of the matrix elements for the color-singlet and color-octet components give the main contribution to the production of heavy quarkonium from the gluon-gluon interaction caused by the emission of additional gluon in the initial state. The numerical results indicate that the contribution of photoproduction processes cannot be negligible for midrapidity in p-p and Pb-Pb collisions at the Large Hadron Collider (LHC) energies.

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5

JACOBSEN, RAFAEL B., GUILHERME F. MARRANGHELLO, CÉSAR A. Z. VASCONCELLOS y ALEXANDRE MESQUITA. "QUARK–GLUON PLASMA IN A BAG MODEL WITH A SOFT SURFACE". International Journal of Modern Physics D 13, n.º 07 (agosto de 2004): 1431–35. http://dx.doi.org/10.1142/s021827180400564x.

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We analyze the implications of quantum hadrodynamics (QHD) and quantum chromodynamics (QCD) to model, respectively, two distinct phases of nuclear matter, a baryon–meson phase and a quark–gluon phase. We develop an equation of state (EoS) in the framework of a quark–meson coupling model for the hadron–meson phase using a new version of the fuzzy bag model with scalar–isoscalar, vector–isoscalar and vector–isovector meson–quark couplings and leptonic degrees of freedom as well as the constrains from chemical equilibrium, baryon number and electric charge conservation. We model the EoS for the QGP phase for asymptotically free massless quarks and gluons using the MIT approach and a temperature and baryon chemical potential dependent bag constant, B(T,μ), which allows an isentropic equilibrium phase transition from a QGP to a hadron gas as determined by thermodynamics. Our predictions yield the EoS and static global properties of neutron stars and protoneutron stars at low and moderate values of temperature. Our results are slightly modified in comparison to predictions based on the standard MIT bag model with a constant bag pressure B.

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6

Kisslinger, Leonard S. "Review of Charmonium and Bottomonium Quark State Production via Relativistic Heavy Ion Collisions". Universe 6, n.º 1 (10 de enero de 2020): 13. http://dx.doi.org/10.3390/universe6010013.

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This is a review of the production of heavy quark states via relativistic heavy ion collisions in RHIC. The heavy quarks here are c, charm quark, and b, bottom quark. The states are charmonium meson states Ψ ( n S ) , with n = 1,2 and upsilon meson states Υ ( m S ) , with m = 1,2,3. Quantum Chromodynamics (QCD) sum rules were used to derive the result that the Ψ ( 2 S ) and Υ ( 3 S ) are mixed hybrid states, which increase their production cross sections. We also review the Ψ ( n S ) and Υ ( m S ) production cross sections via Cu-Cu and Au-Au collisions, which are very important for this review of the production of heavy quark states in RHIC. The possible detection of the Quark Gluon Plasma (QGP) is also reviewed.

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7

Aznauryan, I. G., A. Bashir, V. M. Braun, S. J. Brodsky, V. D. Burkert, L. Chang, Ch Chen et al. "STUDIES OF NUCLEON RESONANCE STRUCTURE IN EXCLUSIVE MESON ELECTROPRODUCTION". International Journal of Modern Physics E 22, n.º 06 (junio de 2013): 1330015. http://dx.doi.org/10.1142/s0218301313300154.

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Studies of the structure of excited baryons are key factors to the N* program at Jefferson Lab (JLab). Within the first year of data taking with the Hall B CLAS12 detector following the 12 GeV upgrade, a dedicated experiment will aim to extract the N* electrocouplings at high photon virtualities Q2. This experiment will allow exploration of the structure of N* resonances at the highest photon virtualities ever achieved, with a kinematic reach up to Q2 = 12 GeV 2. This high-Q2 reach will make it possible to probe the excited nucleon structures at distance scales ranging from where effective degrees of freedom, such as constituent quarks, are dominant through the transition to where nearly massless bare-quark degrees of freedom are relevant. In this document, we present a detailed description of the physics that can be addressed through N* structure studies in exclusive meson electroproduction. The discussion includes recent advances in reaction theory for extracting N* electrocouplings from meson electroproduction off protons, along with Quantum Chromodynamics (QCD)-based approaches to the theoretical interpretation of these fundamental quantities. This program will afford access to the dynamics of the nonperturbative strong interaction responsible for resonance formation, and will be crucial in understanding the nature of confinement and dynamical chiral symmetry breaking in baryons, and how excited nucleons emerge from QCD.

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8

Сабов, В. І., М. Я. Євич y Ю. І. Мага. "MASSES OF PSEUDOSCALAR MESONS IN LOW-ENERGY QUANTUM CHROMODYNAMICS". Scientific Herald of Uzhhorod University.Series Physics 6 (31 de marzo de 2000): 169–74. http://dx.doi.org/10.24144/2415-8038.2000.6.169-174.

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9

PATHAK, KRISHNA KINGKAR y D. K. CHOUDHURY. "Open flavour charmed mesons in a quantum chromodynamics potential model". Pramana 79, n.º 6 (16 de agosto de 2012): 1385–93. http://dx.doi.org/10.1007/s12043-012-0342-1.

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10

Neto, A. Francisco, P. A. Faria da Veiga y M. O’Carroll. "Existence of mesons and mass splitting in strong coupling lattice quantum chromodynamics". Journal of Mathematical Physics 45, n.º 2 (febrero de 2004): 628–41. http://dx.doi.org/10.1063/1.1636000.

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11

WEN, SHUIGUO y JUEPING LIU. "D(1±) AND Ds(1±) MESONS SPECTROSCOPY IN GAUSSIAN SUM RULES". International Journal of Modern Physics E 18, n.º 01 (enero de 2009): 161–74. http://dx.doi.org/10.1142/s0218301309012082.

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The Gaussian sum rules (GSRs) for the D(1±) and Ds(1±) mesons current are obtained by means of Laplacian transformation. Based on it, the GSRs for the mass and the coupling constants of D(1±) and Ds(1±) mesons are worked out. Using the standard input of quantum chromodynamics nonperturbative parameters, the corresponding curves and tables are presented. The results are in accordance well with the experimental data, and more well than those from the Borel sum rule approach.

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12

Lucha, Wolfgang y Franz F. Schöberl. "Instantaneous Bethe–Salpeter view of Goldstone-type pseudoscalar mesons". International Journal of Modern Physics A 31, n.º 36 (28 de diciembre de 2016): 1650202. http://dx.doi.org/10.1142/s0217751x1650202x.

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Describing the lightest pseudoscalar mesons as bound states of quark and antiquark within the framework of an instantaneous Bethe–Salpeter formalism constructed such as to retain (in contrast to Salpeter’s equation) as much information on the relativistic effects provided by the full quark propagator as conceivable allows for a surprisingly simple implementation of their near masslessness mandatory for their interpretability as pseudo-Goldstone bosons related to the spontaneous breaking of the chiral symmetries of quantum chromodynamics.

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13

KUPSC, ANDRZEJ. "DECAYS OF η AND η' MESONS–AN INTRODUCTION". International Journal of Modern Physics E 18, n.º 05n06 (junio de 2009): 1255–70. http://dx.doi.org/10.1142/s0218301309013488.

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Decays of η and η' mesons are a laboratory for low energy strong interactions. The rate of isospin breaking decays into three pions constrain ratios of the light quark masses. Particle distributions from hadronic decays allow to study the elementary processes of the low energy Quantum Chromodynamics: π - π and π - η interactions. Radiative and conversion decays of the η and η' mesons provide information about internal structure of the mesons and the decay mechanism is strongly influenced by vector meson resonances. The lecture gives an introduction to the common decays of η and η' mesons. The main theme of the lecture are three body decays: hadronic decays, radiative decays into π+π-γ, π0γγ and Dalitz decays into ℓ+ℓ-γ.

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14

Li-Bo, Guo y Du Dong-Sheng. "Perturbative Quantum Chromodynamics Effects in { B c → PP } Decays". Chinese Physics Letters 18, n.º 4 (21 de marzo de 2001): 498–500. http://dx.doi.org/10.1088/0256-307x/18/4/310.

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15

Jianguo, Bian y Huang Tao. "Solution of Salpeter Equation for 0 - Mesons Involving the Vacuum Condensates in Quantum Chromodynamics". Chinese Physics Letters 9, n.º 6 (junio de 1992): 285–88. http://dx.doi.org/10.1088/0256-307x/9/6/002.

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16

Upadhyay, A. y M. Batra. "Importance of Nonperturbative QCD Parameters for Bottom Mesons". Advances in High Energy Physics 2014 (2014): 1–4. http://dx.doi.org/10.1155/2014/619783.

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The importance of nonperturbative quantum chromodynamics (QCD) parameters is discussed in context to the predicting power for bottom meson masses and isospin splitting. In the framework of heavy quark effective theory, the work presented here focuses on the different allowed values of the two nonperturbative QCD parameters used in heavy quark effective theory formula, and using the best fitted parameter, masses of the excited bottom meson states injp=1/2+doublet in strange and nonstrange sectors are calculated here. The calculated masses are found to be matching well with experiments and other phenomenological models. The mass splitting and hyperfine splitting have also been analyzed for both strange and nonstrange heavy mesons with respect to spin and flavor symmetries.

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17

Lucha, Wolfgang, Dmitri Melikhov y Hagop Sazdjian. "Compact Exotic Tetraquark Mesons in Large-Nc QCD". EPJ Web of Conferences 191 (2018): 04003. http://dx.doi.org/10.1051/epjconf/201819104003.

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We embark on systematic explorations of the behaviour of tetraquark mesons, i.e., colour-singlet bound states of two quarks and two antiquarks, in the (idealized) limit of a large number of colour degrees of freedom, Nc,; of quantum chromodynamics, QCD. Considering the scattering of two ordinary mesons into two ordinary mesons, we start off with formulating a set of selection criteria that should enable us to unambiguously single out precisely those contributions to all encountered scattering amplitudes that potentially will develop tetraquark poles. Assuming that tetraquark mesons do exist and, if so, emerge in the contributions compatible with our criteria at largest admissible order of Nc; we deduce, for the categories of tetraquarks that exhibit either four or only two different open quark flavours, that the decay rates of these tetraquark types are, at least, of order 1/N2c and that internal consistency requires all the members of the first species to exist pairwise, distinguishable by their favoured two-ordinary-meson decay channels.

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18

Spence, J. R. y J. P. Vary. "Variational Tamm-Dancoff treatment of quantum chromodynamics: The heavy mesons in the valence quark approximation". Physical Review C 52, n.º 3 (1 de septiembre de 1995): 1668–80. http://dx.doi.org/10.1103/physrevc.52.1668.

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19

MEI, ZHONG-HAO y XIANG-QIAN LUO. "EXOTIC MESONS FROM QUANTUM CHROMODYNAMICS WITH IMPROVED GLUON AND QUARK ACTIONS ON THE ANISOTROPIC LATTICE". International Journal of Modern Physics A 18, n.º 31 (20 de diciembre de 2003): 5713–24. http://dx.doi.org/10.1142/s0217751x03017038.

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Hybrid (exotic) mesons, which are important predictions of quantum chromodynamics (QCD), are states of quarks and antiquarks bound by excited gluons. First principle lattice study of such states would help us understand the role of "dynamical" color in low energy QCD and provide valuable information for experimental search for these new particles. In this paper, we apply both improved gluon and quark actions to the hybrid mesons, which might be much more efficient than the previous works in reducing lattice spacing error and finite volume effect. Quenched simulations were done at β=2.6 and on a ξ=3 anisotropic 123×36 lattice using our PC cluster. We obtain 2013±26±71 MeV for the mass of the 1-+ hybrid meson [Formula: see text] in the light quark sector, and 4369±37±99 MeV in the charm quark sector; the mass splitting between the 1-+ hybrid meson [Formula: see text] in the charm quark sector and the spin averaged S-wave charmonium mass is estimated to be 1302±37±99 MeV. As a byproduct, we obtain 1438±32±57 MeV for the mass of a P-wave 1++[Formula: see text] or [Formula: see text] meson and 1499±28±65 MeV for the mass of a P-wave 1++[Formula: see text] meson, which are comparable to their experimental value 1426 MeV for the f1(1420) meson. The first error is statistical, and the second one is systematical. The mixing of the hybrid meson with a four quark state is also discussed.

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20

Kisslinger, Leonard S. "Review of QCD, cosmological phase transitions, QGP, heavy quark meson production enhancement and suppression". International Journal of Modern Physics A 32, n.º 15 (18 de abril de 2017): 1730008. http://dx.doi.org/10.1142/s0217751x17300083.

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This review of the quantum chromodynamics (QCD), the early universe cosmological phase transition from the quark–gluon plasma (QGP) to our present universe (QCDPT), relativistic heavy ion collisions (RHIC) which can produce the QGP, the possible detection of the QGP produced by the production of mixed hybrid heavy quark mesons. We also review the recent studies of the production of mixed heavy quark hybrids via RHIC and heavy quark meson suppression in p-Pb and Pb–Pb collisions.

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21

Dai, Yuan-ben, Chao-shang Huang, Ming-qiu Huang, Hong-ying Jin y Chun Liu. "Decay Widths of Excited Heavy Mesons from Quantum Chromodynamics Sum Rules in the Infinite Mass Limit". Chinese Physics Letters 15, n.º 8 (1 de agosto de 1998): 558–60. http://dx.doi.org/10.1088/0256-307x/15/8/005.

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22

Cahill, RT, J. Praschifka y CJ Burden. "Diquarks and the Bosonisation of QCD". Australian Journal of Physics 42, n.º 2 (1989): 161. http://dx.doi.org/10.1071/ph890161.

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Previously the functional integral formulation of quantum chromodynamics <QCD) has been transformed into one involving colour singlet and colour octet bilocal fields describing qq states. While useful in determining the effective action for the observable colour singlet mesons, this formulation is of no use in determining the effective action for the baryon states. Here we show that there exists an alternative bosonisation of QCD in which the colour singlet meson fields and the colour triplet diquark fields form a complete set of functional integration variables. These diquark fields play an essential role in the colour singlet baryon states.

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23

Girard, Ralph y Alexander Langnau. "The light-cone approach for the calculation of hadronic states". Canadian Journal of Physics 67, n.º 12 (1 de diciembre de 1989): 1162–67. http://dx.doi.org/10.1139/p89-195.

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We present an application of the recently proposed method of discretized light-cone quantization to quantum chromodynamics (QCD). We present the general method of light-cone quantization and point out its usefulness for the derivation of covariant integral equations for bound states. We then apply it to QCD and obtain the integral equation for the bound states in the valence sector of the mesons. The numerical solution of the integral equation shows a nice transition to the continuum. The conclusion summarizes the main results and discusses briefly what should be the next improvements of this method.

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24

Brodsky, Stanley J. y Robert Shrock. "Condensates in quantum chromodynamics and the cosmological constant". Proceedings of the National Academy of Sciences 108, n.º 1 (15 de diciembre de 2010): 45–50. http://dx.doi.org/10.1073/pnas.1010113107.

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Casher and Susskind [Casher A, Susskind L (1974) Phys Rev 9:436–460] have noted that in the light-front description, spontaneous chiral symmetry breaking is a property of hadronic wavefunctions and not of the vacuum. Here we show from several physical perspectives that, because of color confinement, quark and gluon condensates in quantum chromodynamics (QCD) are associated with the internal dynamics of hadrons. We discuss condensates using condensed matter analogues, the Anti de Sitter/conformal field theory correspondence, and the Bethe–Salpeter–Dyson–Schwinger approach for bound states. Our analysis is in agreement with the Casher and Susskind model and the explicit demonstration of “in-hadron” condensates by Roberts and coworkers [Maris P, Roberts CD, Tandy PC (1998) Phys Lett B 420:267–273], using the Bethe–Salpeter–Dyson–Schwinger formalism for QCD-bound states. These results imply that QCD condensates give zero contribution to the cosmological constant, because all of the gravitational effects of the in-hadron condensates are already included in the normal contribution from hadron masses.

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25

Kisslinger, Leonard S. y Debasish Das. "Review of QCD, quark–gluon plasma, heavy quark hybrids, and heavy quark state production in p–p and A–A collisions". International Journal of Modern Physics A 31, n.º 07 (2 de marzo de 2016): 1630010. http://dx.doi.org/10.1142/s0217751x16300106.

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This is a review of the Quantum Chromodynamics Cosmological Phase Transitions, the quark–gluon plasma, the production of heavy quark states via [Formula: see text]–[Formula: see text] collisions and Relativistic Heavy Ion Collisions (RHIC) using the mixed hybrid theory for the [Formula: see text] and [Formula: see text] states; and the possible detection of the quark–gluon plasma via heavy quark production using RHIC. Recent research on fragmentation for the production of [Formula: see text] mesons is reviewed, as is future theoretical and experimental research on the Collins and Sivers fragmentation functions for pions produced in polarized [Formula: see text]–[Formula: see text] collisions.

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26

Bardeen, William A. "On the Large Nc Expansion in Quantum Chromodynamics". Fortschritte der Physik 50, n.º 5-7 (mayo de 2002): 483–88. http://dx.doi.org/10.1002/1521-3978(200205)50:5/7<483::aid-prop483>3.0.co;2-b.

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27

PLESSAS, WILLIBALD. "EFFECTIVE DEGREES OF FREEDOM IN LOW-ENERGY QUANTUM CHROMODYNAMICS". Modern Physics Letters A 28, n.º 26 (22 de agosto de 2013): 1360022. http://dx.doi.org/10.1142/s0217732313600225.

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Confinement and spontaneous breaking of chiral symmetry are assumed to generate the governing degrees of freedom of low-energy quantum chromodynamics. On this basis a relativistic constituent-quark model is constructed and formulated along an invariant mass operator within Poincaré-invariant quantum mechanics. The model is effectively applied to the spectroscopy of all known baryons of flavors u, d, s, c and b. The mass-operator eigenstates are furthermore tested with regard to the baryon electromagnetic and axial form factors. Through using the point form of relativistic quantum mechanics, these observables are obtained in a manifestly covariant manner. For all light and strange baryon ground states the electroweak structures are reproduced either in good agreement with phenomenology or, if no experimental data exist, in consistency with results available from lattice quantum chromodynamics. It is concluded that the relativistic constituent-quark model, relying on {QQQ} Fock states only, provides a universal framework for the description of low-energy baryons. The most important ingredients are spontaneous chiral-symmetry breaking and strict relativistic invariance.

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28

Romano, Raffaele. "An Open Quantum System Approach to the B-Mesons System". International Journal of Theoretical Physics 42, n.º 10 (octubre de 2003): 2505–13. http://dx.doi.org/10.1023/b:ijtp.0000005971.45408.81.

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29

SHYAM, RADHEY. "OPEN AND HIDDEN STRANGENESS PRODUCTION IN NUCLEON-NUCLEON COLLISIONS". International Journal of Modern Physics E 18, n.º 05n06 (junio de 2009): 1359–70. http://dx.doi.org/10.1142/s0218301309013579.

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Strange meson production reactions are expected to provide information on the manifestation of quantum chromodynamics in the non-perturbative regime of energies larger than that of the low energy pion physics. The K meson contains a strange quark (s) or antiquark [Formula: see text] while the η meson has hidden strangeness as it contains some component of the [Formula: see text] pair. In this lecture we present an overview of describing the production of K and η mesons in nucleon-nucleon collisions within an effective Lagrangian model (ELM) where meson production proceeds via excitation, propagation and subsequent decay of intermediate baryonic resonant states. Specific examples are discussed where proper understanding of the data is still lacking.

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30

Chernodub, M. N. "Superconducting properties of vacuum in strong magnetic field". International Journal of Modern Physics D 23, n.º 06 (mayo de 2014): 1430009. http://dx.doi.org/10.1142/s0218271814300092.

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We discuss superconducting phases of vacuum induced by strong magnetic field in the electroweak model and in Quantum Chromodynamics (QCD) at zero temperature. In these phases, the vacuum behaves as an anisotropic inhomogeneous superconductor which supports superconductivity along the axis of the magnetic field while in the transversal directions, the superconductivity does not exist. The magnetic-field-induced anisotropic superconductivity appears as a result of condensation of electrically charged spin-one particles, which are elementary W bosons in the case of the electroweak model and composite quark–antiquark pairs with quantum numbers of ρ-mesons in the case of QCD. Due to the anisotropic nature of superconductivity, the Meissner effect is absent. Intrinsic inhomogeneities of the superconducting ground state are characterized by ensembles of certain topological vortices in an analogy with a mixed Abrikosov state of a type-II superconductivity.

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31

Yepez-Martinez, Tochtli, Osvaldo Civitarese y Peter O. Hess. "RPA treatment of a motivated QCD Hamiltonian in the SO(4) (2 + 1)-flavor limit: Light and strange mesons". International Journal of Modern Physics E 26, n.º 04 (abril de 2017): 1750012. http://dx.doi.org/10.1142/s0218301317500124.

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The SO(4) symmetry of a sector of the quantum chromodynamics (QCD) Hamiltonian was analyzed in a previous work. The numerical calculations were then restricted to a particle–hole (ph) space and the comparison with experimental data was reasonable in spite of the complexity of the QCD spectrum at low energy. Here on, we continue along this line of research and show our new results of the treatment of the QCD Hamiltonian in the SO(4) representation, including ground state correlations by means of the Random Phase Approximation (RPA). We are able to identify, within this model, states which may be associated to physical pseudo-scalar and vector mesons, like [Formula: see text], as well as the pion ([Formula: see text]).

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32

Andrianov, Alexander, Vladimir Andrianov y Domenec Espriu. "Chiral Perturbation Theory vs. Linear Sigma Model in a Chiral Imbalance Medium". Particles 3, n.º 1 (8 de enero de 2020): 15–22. http://dx.doi.org/10.3390/particles3010002.

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We compare the chiral perturbation theory (ChPT) and the linear sigma model (LSM) as realizations of low energy quantum chromodynamics (QCD) for light mesons in a chirally-imbalanced medium. The relations between the low-energy constants of the chiral Lagrangian and the corresponding constants of the linear sigma model are established as well as the expressions for the decay constant of π -meson in the medium and for the mass of the a 0 . In the large N c count taken from QCD the correspondence of ChPT and LSM is remarkably good and provides a solid ground for the search of chiral imbalance manifestations in pion physics. A possible experimental detection of chiral imbalance (and therefore a phase with local parity breaking) is outlined in the charged pion decays inside the fireball.

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33

Xu, Xiao-Ming y H. J. Weber. "Inelastic meson-meson scattering in hadronic matter". Modern Physics Letters A 35, n.º 33 (15 de julio de 2020): 2030016. http://dx.doi.org/10.1142/s0217732320300165.

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We review studies of inelastic meson-meson scattering. In nonperturbative schemes with chiral-perturbation-theory Lagrangians and in models based on effective meson Lagrangians, inelastic meson-meson scattering leads to the successful identification of resonances in meson-meson reactions, adequate inclusion of final state interactions in particle decays, and so on. For mesons of which each consists of a quark and an antiquark, inelastic meson-meson scattering may be caused by quark-antiquark annihilation, quark-antiquark creation, quark interchange, and quark-antiquark annihilation and creation. In transition amplitudes for meson-meson scattering mesonic quark-antiquark relative-motion wave functions depend on hadronic matter, and transition potentials are given in perturbative quantum chromodynamics. Via transition amplitudes the cross sections for inelastic meson-meson scattering depend on the temperature of hadronic matter. Some prominent temperature dependence of the cross sections has been found. Inelastic meson-meson scattering becomes even more significant in proton-proton collisions and lead-lead collisions at the Large Hadron Collider.

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34

Dzierba, Alex R. "THE SCIENCE OF CONFINEMENT AND THE GLUEX/HALL D PROJECT AT JEFFERSON LAB". International Journal of Modern Physics A 18, n.º 03 (30 de enero de 2003): 397–404. http://dx.doi.org/10.1142/s0217751x03014319.

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One of the outstanding and fundamental questions in physics is the quantitative understanding of the confinement of quarks and gluons in quantum chromodynamics (QCD). Confinement is a unique feature of QCD. Exotic hybrid mesons manifest gluonic degrees of freedom and their spectroscopy will provide the crucial data needed to test assumptions in lattice QCD and phenomenology leading to confinement. Photo-production is expected to be particularly effective in producing exotic hybrids but data using photon probes are sparse. At Jefferson Lab, plans are underway to use the coherent bremsstrahlung technique to produce a linearly polarized photon beam. A solenoid-based hermetic detector will be used to collected data on meson production and decays with statistics that will exceed the current photoproduction data in hand by several orders of magnitude after the first year of running. In order to reach the ideal photon energy of 9 GeV/c for this mapping of the exotic spectra, the energy of the Jefferson Lab electron accelerator, CEBAF, will be doubled from its current maximum of 6 GeV to 12 GeV. The physics and project are described.

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35

Zhitnitsky, I. R., V. V. Barakhovsky y O. M. Cohen. "Do the polarization effects “die out” in two-to-two reactions at high energies in quantum chromodynamics?" Nuclear Physics B - Proceedings Supplements 25 (marzo de 1992): 211–23. http://dx.doi.org/10.1016/0920-5632(92)90397-b.

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36

Loiseau, B. "Skyrmions and effective Lagrangians". Canadian Journal of Physics 67, n.º 12 (1 de diciembre de 1989): 1168–79. http://dx.doi.org/10.1139/p89-196.

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The need to model quantum chromodynamics (QCD) at low energy is emphasized. An outline of the1/NC expansion of QCD, for large NC, shows the deep link between the Skyrme effective Lagrangian and QCD. The Skyrme model, built from the nonlinear σ model plus a stabilizer term related to vector dominance, is briefly described. The model satisfies like QCD chiral symmetry. We illustrate how the gauged Wess–Zumino action demonstrates that the topological current can be identified with the baryon current. We recall how one can show that the topological soliton is a fermion for odd NC. An example of an effective Lagrangian, built from π and low-mass vector mesons, ω, ρ, and A1 fields, is given. It describes rather well low-energy meson and baryon physics. Predictions of effective Lagrangians of the Skyrme type on meson–meson, meson–baryon, and baryon–baryon scatterings at low energy are depicted. A two-phase chiral symmetric model, the chiral bag, is introduced. It contains an inner core of confined quarks and gluons surrounded by meson fields in the topological configuration of a Skyrmion. It can describe nuclei from the low- to the high-energy range.

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37

Gorman, RM y Bruce HJ McKellar. "Quark Mass Thresholds in Quarkonium Systems". Australian Journal of Physics 44, n.º 6 (1991): 619. http://dx.doi.org/10.1071/ph910619.

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We consider the role of quark mass thresholds in quarkonium systems, which are formed by the binding of heavy quark-antiquark pairs and are manifest in the IfJ and Y families of mesons. Such systems provide a probe of the interactions of quarks in a region accessible to the predictions of perturbative quantum chromodynamics (QCD), as well as in the long range region where the interaction is expected to show confining behaviour consistent with our knowledge of light quark systems. A prescription for deriving an interaction linking these two limits has been developed by Buchmiiller, Grunberg and Tye (1980, 1981) and has been successfully applied to the IfJ and Y systems, leading them to suggest a value for the QCD scale parameter AMS" of 500 MeV. In this work we extend this formalism by incorporating the effects of allowing the virtual quarks which contribute to the interaction to have finite masses. These masses must be considered energy dependent, and it is found that while the properties of IfJ and Y states are insensitive to the detailed way in which the masses vary, the presence of mass thresholds has the effect of weakening the ability of this model to set the value of AMS ' with 500 MeV becoming an approximate lower bound.

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38

Mao, Qiang, Hua-Xing Chen y Hui-Min Yang. "Identifying the Λb(6146)0 and Λb(6152)0 as D-Wave Bottom Baryons". Universe 6, n.º 6 (23 de junio de 2020): 86. http://dx.doi.org/10.3390/universe6060086.

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We study the Λ b ( 6146 ) 0 and Λ b ( 6152 ) 0 recently observed by LHCb using the method of Quantum Chromodynamics (QCD) sum rules within the framework of heavy quark effective theory. Our results suggest that they can be interpreted as D-wave bottom baryons of J P = 3 / 2 + and 5 / 2 + respectively, both of which contain two λ -mode excitations. We also investigate other possible assignments containing ρ -mode excitations. We extract all the parameters that are necessary to study their decay properties when using the method of light-cone sum rules. We predict masses of their strangeness partners to be m Ξ b ( 3 / 2 + ) = 6.26 − 0.14 + 0.11 GeV and m Ξ b ( 5 / 2 + ) = 6.26 − 0.14 + 0.11 GeV with the mass splitting Δ M = m Ξ b ( 5 / 2 + ) − m Ξ b ( 3 / 2 + ) = 4.5 − 1.5 + 1.9 MeV, and propose to search for them in future CMS, EIC, and LHCb experiments.

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39

Kitazawa, Noriaki y Yuki Sakai. "An approach to the instanton effect in B system". International Journal of Modern Physics A 33, n.º 02 (20 de enero de 2018): 1850017. http://dx.doi.org/10.1142/s0217751x18500173.

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We discuss the constraint on the size of QCD instanton effects in low-energy effective theory. Among various instanton effects in meson mass spectrum and dynamics, we concentrate on the instanton-induced masses of light quarks. The famous instanton-induced six-quark interaction, so-called ’t Hooft vertex, could give nonperturbative quantum corrections to light quark masses. Many works have already been achieved to constrain the mass corrections in light meson system, or the system of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], and now we know for a fact that the instanton-induced mass of up-quark is too small to realize the solution of the strong CP problem by vanishing current mass of up-quark. In this work, we give a constraint on the instanton-induced mass correction to light quarks from the mass spectrum of heavy mesons, [Formula: see text], [Formula: see text], [Formula: see text] and their antiparticles. To accomplish this, the complete second-order chiral symmetry breaking terms are identified in heavy meson effective theory. We find that the strength of the constraint from heavy meson masses is at the same level of that from light mesons, and it would be made even stronger by more precise data from future [Formula: see text] factories and lattice calculations.

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40

SCHILLING, K. y G. S. BALI. "THE STATIC QUARK-ANTIQUARK-POTENTIAL: A 'CLASSICAL' EXPERIMENT ON THE CONNECTION MACHINE CM-2". International Journal of Modern Physics C 04, n.º 06 (diciembre de 1993): 1167–77. http://dx.doi.org/10.1142/s0129183193000926.

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This meeting produces another evidence that present parallel computers are (a) real instruments of computational physics, (b) largely in the hands of still-pioneers, (c) efficiently promoted by basic research groups with large-scale computational needs. Progress in parallel computing is carried by two types of such groups, that either follow the build-it-yourself or the early-use strategies. In this contribution, we describe, as an example to the second approach, the Wuppertal university pilot project in applied parallel computing. We report in particular about one of our key applications in theoretical particle physics on the Connection Machine CM-2: a high statistics computer experiment to determine the static quark-antiquark potential from quenched quantum chromodynamics.

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41

Datta, Saumen, Rajiv Gavai y Sourendu Gupta. "Quark Number Susceptibilities and Equation of State in QCD at Finite μB". Proceedings 13, n.º 1 (3 de junio de 2019): 5. http://dx.doi.org/10.3390/proceedings2019013005.

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One of the main goals of the cold baryonic matter (CBM) experiment at FAIR is to explore the phases of strongly interacting matter at finite temperature and baryon chemical potential μ B . The equation of state of quantum chromodynamics (QCD) at μ B > 0 is an essential input for the CBM experiment, as well as for the beam energy scan in the Relativistic Heavy Ion Collider(RHIC) experiment. Unfortunately, it is highly nontrivial to calculate the equation of state directly from QCD: numerical Monte Carlo studies on lattice are not useful at finite μ B . Using the method of Taylor expansion in chemical potential, we estimate the equation of state, namely the baryon number density and its contribution to the pressure, for two-flavor QCD at moderate μ B . We also study the quark number susceptibilities. We examine the technicalities associated with summing the Taylor series, and explore a Pade resummation. An examination of the Taylor series can be used to get an estimate of the location of the critical point in μ B , T plane.

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42

Rischke, Dirk H. "The Phases of Quantum Chromodynamics: From Confinement to Extreme Environments The Phases of Quantum Chromodynamics: From Confinement to Extreme Environments , John B. Kogut , Mikhail A. Stephanov Cambridge U. Press, New York, 2004. $110.00 (364 pp.). ISBN 0-521-80450-7". Physics Today 58, n.º 9 (septiembre de 2005): 60–62. http://dx.doi.org/10.1063/1.2117829.

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43

VOLOSHIN, M. B. "DECAYS OF b HADRONS AND A POSSIBLE NEW FOUR-QUARK INTERACTION". International Journal of Modern Physics A 16, n.º 12 (10 de mayo de 2001): 2205–14. http://dx.doi.org/10.1142/s0217751x01003366.

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A possibility is considered of explaining the low experimental value of the ratio of the lifetimes τ(Λb)/τ (Bd) by a new "centiweak" four-quark interaction, i.e. with a strength on the order of 10-2GF. It is noted that the considered interaction can also improve agreement with the data on low semileptonic branching ratio B sl (B) in B meson decays with a simultaneous slight decrease in the prediction for the average charm yield in those decays. The proposed new interaction modifies within the present experimental limits the predictions for differences of lifetimes among B mesons, and can thus be probed by more precise data on these differences. A sample model is briefly discussed, where the new interaction arises through a weak SU(2) singlet scalar field with quantum numbers of a diquark.

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44

Pedlar, Todd K. "Exotic and Conventional Bottomonium Physics Prospects at Belle II". EPJ Web of Conferences 181 (2018): 01022. http://dx.doi.org/10.1051/epjconf/201818101022.

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The Belle II experiment, being constructed at the KEK laboratory in Japan, represents a substantial upgrade of both the Belle detector and the KEKB accelerator. It is expected that Belle II will collect 50 times more data than existing B-Factory samples beginning in 2019. Belle II is uniquely capable of studying the so-called "XYZ" particles: heavy exotic hadrons consisting of more than three quarks. First discovered by Belle, these now number in the dozens, and represent the emergence of a new category within Quantum Chromodynamics. In this article we summarize the capabilities of Belle II to explore both exotic and conventional bottomonium physics, with a particular focus on the physics reach of the first data, where opportunities exist to make an immediate impact in this area.

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45

Bicudo, Pedro, Marco Cardoso, Antje Peters, Martin Pflaumer y Marc Wagner. "Tetraquark resonances computed with static lattice QCD potentials and scattering theory". EPJ Web of Conferences 175 (2018): 05017. http://dx.doi.org/10.1051/epjconf/201817505017.

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We study tetraquark resonances with lattice QCD potentials computed for two static quarks and two dynamical quarks, the Born-Oppenheimer approximation and the emergent wave method of scattering theory. As a proof of concept we focus on systems with isospin I = 0, but consider different relative angular momenta l of the heavy b quarks. We compute the phase shifts and search for S and T matrix poles in the second Riemann sheet. We predict a new tetraquark resonance for l = 1, decaying into two B mesons, with quantum numbers I(JP) = 0(1−), mass [see formula in PDF] MeV and decay width [see formula in PDF] MeV.

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46

ANISOVICH, V. V., S. M. GERASYUTA y A. V. SARANTSEV. "LOW-LYING MESON SPECTROSCOPY AND CONFINEMENT". International Journal of Modern Physics A 06, n.º 04 (10 de febrero de 1991): 625–66. http://dx.doi.org/10.1142/s0217751x9100037x.

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The paper is devoted to the construction of low-energy quark-scattering amplitudes. The amplitudes of dressed quarks qq→qq and [Formula: see text] are calculated in the framework of the dispersion N/D method with the help of the iteration bootstrap procedure including two types of point-like input interactions, namely the four-fermion interaction with quantum numbers of the gluon and four-fermion interaction induced by instantons (the exchanges of white states with JP=0±). The mass values of the lowest mesons (JP=0−, 1−, 0+) and their quark content are obtained. In the colour meson channel a bound state was found which corresponds to the constituent gluon with the mass MG=0.67 GeV . The qq-amplitudes in the colour state [Formula: see text] have the diquark levels with JP=0+ and the masses mud=0.72 GeV and mus=mds=0.86 GeV . The interaction of dressed quarks appeared to be an effectively short-range one. The calculated amplitudes satisfy the Okubo-Zweig-Iisuka rule. The creation of mesons (pion included) is mainly due to the gluon exchange. The mesons with heavy quarks (c and b) are considered also, using the calculated forces. We discuss the possibility of constructing the amplitudes which take into account the quark confinement.

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47

Balachandran, A. P. "QCD breaks Lorentz invariance and colour". Modern Physics Letters A 31, n.º 10 (28 de marzo de 2016): 1650060. http://dx.doi.org/10.1142/s0217732316500607.

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In the previous work [A. P. Balachandran and S. Vaidya, Eur. Phys. J. Plus 128, 118 (2013)], we have argued that the algebra of non-Abelian superselection rules is spontaneously broken to its maximal Abelian subalgebra, that is, the algebra generated by its completing commuting set (the two Casimirs, isospin and a basis of its Cartan subalgebra). In this paper, alternative arguments confirming these results are presented. In addition, Lorentz invariance is shown to be broken in quantum chromodynamics (QCD), just as it is in quantum electrodynamics (QED). The experimental consequences of these results include fuzzy mass and spin shells of coloured particles like quarks, and decay life times which depend on the frame of observation [D. Buchholz, Phys. Lett. B 174, 331 (1986); D. Buchholz and K. Fredenhagen, Commun. Math. Phys. 84, 1 (1982; J. Fröhlich, G. Morchio and F. Strocchi, Phys. Lett. B 89, 61 (1979); A. P. Balachandran, S. Kürkçüoğlu, A. R. de Queiroz and S. Vaidya, Eur. Phys. J. C 75, 89 (2015); A. P. Balachandran, S. Kürkçüoğlu and A. R. de Queiroz, Mod. Phys. Lett. A 28, 1350028 (2013)]. In a paper under preparation, these results are extended to the ADM Poincaré group and the local Lorentz group of frames. The renormalisation of the ADM energy by infrared gravitons is also studied and estimated.

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48

Muñoz Franco, Lucía. "Erratum to “Proceedings of the QCD 08, 14th High-Energy Physics International Conference On Quantum ChromoDynamics” [Nucl. Phys. B (Proc. Suppl.) 186 (2009) 1–450]". Nuclear Physics B - Proceedings Supplements 207-208 (octubre de 2010): 431. http://dx.doi.org/10.1016/j.nuclphysbps.2010.11.001.

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49

Soloveva, O., P. Moreau, L. Oliva, V. Voronyuk, V. Kireyeu, T. Song y E. Bratkovskaya. "Exploring the Partonic Phase at Finite Chemical Potential in and out-of Equilibrium". Particles 3, n.º 1 (2 de marzo de 2020): 178–92. http://dx.doi.org/10.3390/particles3010015.

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We study the influence of the baryon chemical potential μ B on the properties of the Quark–Gluon–Plasma (QGP) in and out-of equilibrium. The description of the QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature T c from lattice Quantum Chromodynamics (QCD). We study the transport coefficients such as the ratio of shear viscosity η and bulk viscosity ζ over entropy density s, i.e., η / s and ζ / s in the ( T , μ ) plane and compare to other model results available at μ B = 0 . The out-of equilibrium study of the QGP is performed within the Parton–Hadron–String Dynamics (PHSD) transport approach extended in the partonic sector by explicitly calculating the total and differential partonic scattering cross sections based on the DQPM and the evaluated at actual temperature T and baryon chemical potential μ B in each individual space-time cell where partonic scattering takes place. The traces of their μ B dependences are investigated in different observables for symmetric Au + Au and asymmetric Cu + Au collisions such as rapidity and m T -distributions and directed and elliptic flow coefficients v 1 , v 2 in the energy range 7.7 GeV ≤ s N N ≤ 200 GeV.

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50

Mavromatos, Nick E. "Models & Searches of CPT Violation: a personal, very partial, list". EPJ Web of Conferences 166 (2018): 00005. http://dx.doi.org/10.1051/epjconf/201816600005.

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In this talk, first I motivate theoretically, and then I review the phenomenology of, some models entailing CPT Violation (CPTV). The latter is argued to be responsible for the observed matter-antimatter asymmetry in the Cosmos, and may owe its origin to either Lorentz-violating background geometries, whose effects are strong in early epochs of the Universe but very weak today, being temperature dependent in general, or to an ill-defined CPT generator in some quantum gravity models entailing decoherence of quantum matter as a result of quantum degrees of freedom in the gravity sector that are inaccessible to the low-energy observers. In particular, for the latter category of CPTV, I argue that entangled states of neutral mesons (Kaons or B-systems), of central relevance to KLOE-2 experiment, can provide smoking-gun sensitive tests or even falsify some of these models. If CPT is ill-defined one may also encounter violations of the spin-statistics theorem, with possible consequences for the Pauli Exclusion Principle, which I only briefly touch upon.

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