Searcharxiv⌕ Search

arXiv subjects

Pengfei Zhuang

Publications and source records attributed to Pengfei Zhuang.

159 records · Page 9Linked to original sources
arXiv2002

Charge Neutrality Effects on 2-flavor Color Superconductivity

The effect of electric and color neutrality on 2-flavor color superconductivity has been investigated. It has been found that the effect of the charge neutrality on a 2-flavor quark system is very different from that on a 3-flavor system. The BCS diquark pair in 2-flavor color superconducting phase has been largely reduced by the large Fermi momentum of electron, the diquark condensate first increases with the increasing of quark's chemical potential $μ$,then decreases rapidly and finally disappears at about $μ=535MeV$, at which the thermodynamic potential equals to that in the neutral normal 2-flavor quark matter.

hep-ph↗
arXiv2001

Multiplicity Moments and Hard Processes in Relativistic Heavy Ion Collisions

The normalized multiplicity moments and their relation with soft and hard processes in relativistic heavy ion collisions are analyzed in a general two-component model. It is found that, the strong fluctuations in binary collision number N_c in minimum-bias events can enhance the hard component, especially for the higher order moments. This enhancement can not be effectively described by modifying the participant number in the one-component model.

nucl-th↗
arXiv2001

Color Superconductivity at Moderate Density

The effect of color breaking on colored quarks' chiral condensates has been investigated at zero temperature and moderate baryon density. It is found that the influence of the diquark condensate on different colored quarks is very small.

hep-ph↗
arXiv2001

Decay Process Sigma to 2 Pions and Chiral Phase Transition

The decay process sigma to 2 pions at high temperature and density and its relation with chiral phase transition are discussed in the framework of the NJL model. The decay rate for the process sigma to 2 pions is calculated in the whole temperature and density region. The contribution of the final state pion statistics to the decay rate is discussed. The maximum decay rate at different chemical potential is computed. Finally, we investigate the relation between the starting point of the decay process and the critical point of the first-order chiral phase transition.

nucl-th↗
arXiv2001

Transverse Momentum Distribution of J/Psi's in Pb-Pb Collisions and Gluon Rescattering

The transverse momentum dependence of J/Psi suppression in relativistic heavy ion collisions is calculated from initial state gluon rescattering not only with nucleons but also with prompt gluons produced in nucleon-nucleon collisions in the early phase of the reaction. The second mechanism is new and turns out to be important in a description of the data for central collisions.

nucl-th↗
arXiv2001

Transverse Momentum Dependence of Anomalous J/ψSuppression in Pb-Pb Collisions

The recently published data for $ $ for $J/ψ$ production in Pb-Pb collisions at 158 A GeV are analyzed. For low values of transverse energy $E_t$, where normal suppression dominates, $ (E_t)$ scales with the path length of the gluons which fuse to make the $J/ψ$. In the $E_t$ domain of anomalous suppression $ (E_t)$ is found to rise linearly with the relative amount of anomalous suppression. This empirical law is reproduced within an analytically solvable transport model which allows high $p_t$ $J/ψ$'s to escape anomalous suppression. Interpreted in this way, the data for $ (E_t)$ lead to an estimate of $t_A \sim 4$ fm/$c$ for the duration of anomalous suppression.

nucl-th↗
arXiv2001

The Mesonic Fluctuations and Corrections in the Chiral Symmetry Breaking Vacuum

The mesonic quantum fluctuations and their corrections on the chiral condensate and pion polarization function are investigated in the self-consistent scheme of SU(2) Nambu-Jona-Lasinio model by exactly calculating the next-to-leading order (NLO) Feynman diagrams in $1/N_c$ expansion. While the fluctuations and corrections depend strongly on the meson's three-momentum cut-off $Λ_M$, no chiral symmetry restoration is found since the cancellation between the NLO and the one-quark-loop diagram with quark mass deviated from the mean-field value.

hep-ph↗
arXiv2001

Meson Effects on Chiral Condensate at Finite Density

Meson corrections on chiral condensate up to next-to-leading order in $1/N_c$ expansion at finite density are investigated in NJL model with chiral symmetry explicitly breaking. Compared with the mean-field results, the chiral phase transition is still of first order, while the properties at the critical density of chiral phase transition are found to change significantly.

hep-ph↗
arXiv1999

S-wave $π- π$ Scattering Lengths in the SU(2) NJL Model Beyond Mean-field Approximation

The S-wave $π- π$ scattering lengths $a_0$ and $a_2$ are calculated to the lowest order of $1/N_c$ expansion in the general framework of SU(2) NJL model beyond mean-field approximation. It is shown that using the universal curve of $a_0$ and $a_2$ the four NJL parameters, i.e., the current quark mass $m_0$, the four fermion coupling constant $G$, the quark momentum cut-off $Λ_f$ and the meson momentum cut-off $Λ_b$, also the S-wave $π- π$ scattering lengths in NJL model can be uniquely determined.

hep-ph↗
arXiv1999

$π- π$ Scattering Lengths and Chiral Condensate in NJL Model

Within the general framework of SU(2) Nambu-Jona-Lasinio model beyond mean-field approximation, the S-wave $π- π$ scattering lengths $a_0^0$ and $a_0^2$ are calculated. The numerical results are in agreement with that analyzed from recent experiment $πN \to ππN$ data by using Chew-Low-Goebel technique, and the corresponding chiral condensate $<{\bar q}q>$ is around $-(250 {\rm MeV})^3$, which is close to the ones obtained from lattice and sum rules.

hep-ph↗
arXiv1999

Massive Meson Fluctuation in NJL Model

Based on the self-consistent scheme beyond mean-field approximation in the large $N_c$ expansion, including current quark mass explicitly, a general scheme of SU(2) NJL model is developed. To ensure the quark self-energy expanded in the proper order of $N_c$, an approximate internal meson propagator is deduced, which is in order of $O(1/N_c)$. In our scheme, adopting the method of external momentum expansion, all the Feynman diagrams are calculated in a unified way by only expanding the quark propagator. Our numerical results show, that different from the mean field approximation in which the explicitly chiral symmetry breaking is invisible, the effect of finite pion mass can be seen clearly when beyond mean-field approximation.

hep-ph↗
arXiv1996

Equal-Time Hierarchies for Quantum Transport Theory

We investigate in the equal-time formalism the derivation and truncation of infinite hierarchies of equations of motion for the energy moments of the covariant Wigner function. From these hierarchies we then extract kinetic equations for the physical distribution functions which are related to low-order energy moments, and show how to determine the higher order moments in terms of these lowest order ones. We apply the general formalism to scalar and spinor QED with classical background fields and compare with the results derived from the three-dimensional Wigner transformation method.

hep-ph↗
arXiv1996

Comment on ``Relativistic kinetic equations for electromagnetic, scalar and pseudoscalar interactions''

It is found that the extra quantum constraints to the spinor components of the equal-time Wigner function given in a recent paper by Zhuang and Heinz should vanish identically. We point out here the origin of the error and give an interpretation of the result. However, the principal idea of obtaining a complete equal-time transport theory by energy averaging the covariant theory remains valid. The classical transport equation for the spin density is also found to be incorrect. We give here the correct form of that equation and discuss briefly its structure.

hep-ph↗