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Register a new userDual chiral density waves in nuclear matter
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We study inhomogeneous chiral phases in nuclear matter using a hadronic model with the parity doublet structure. With an extended ansatz for the dual chiral density wave off the chiral limit, we numerically determine the phase structure. A new type of dual chiral density wave where the condensate has nonvanishing space average is confirmed and it comes to occupy a wide range of low density region as the chiral invariant mass parameter is lowered.
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We study the Dual Chiral Density Wave (DCDW) in nuclear matter using a hadronic model with the parity doublet structure. We first extend the ordinary DCDW ansatz so as to incorporate the effect of an explicit chiral symmetry breaking. Then via numerically evaluating and minimizing the effective potential, we determine the phase structure. We find, in addition to the ordinary DCDW phase where the space average of the chiral condensate vanishes, a new DCDW phase (sDCDW) with a nonvanishing space average depending on the value of the chiral invariant mass parameter.
Properties of cold nuclear matter are studied within a generalized Nambu-Jona-Lasinio model formulated on the level of constituent nucleons. The model parameters are chosen to reproduce simultaneously the observed nucleon and pion masses in vacuum as well as saturation properties of nuclear matter. The strongest constraints on these parameters are given by the empirical values of the nucleon effective mass and compression modulus at nuclear saturation density. A preferable value of the cut-off momentum, determining density of active quasinucleon states in the Dirac sea, is estimated to about 400 MeV/c. With the most reasonable choice of model parameters we have found a first order phase transition of the liquid-gas type at subsaturation densities and the gradual restoration of chiral symmetry at about 3 times the saturation density. Fluctuations of the scalar condensate around its mean-field value are estimated and shown to be large in the vicinity of chiral transition.
It is shown that the spin polarized condensate appears in quark matter at high baryon density and low temperature due to the tensor-type four-point interaction in the Nambu-Jona-Lasinio-type model as a low energy effective theory of quantum chromodynamics. It is indicated within this low energy effective model that the chiral symmetry is broken again by the spin polarized condensate as increasing the quark number density, while the chiral symmetry restoration occurs in which the chiral condensate disappears at a certain density.
Background: It has been proposed that the azimuthal distributions of heavy flavor quark-antiquark pairs may be modified in the medium of a heavy-ion collision. Purpose: This work tests this proposition through next-to-leading order (NLO) calculations of the azimuthal distribution, $dsigma/dphi$, including transverse momentum broadening, employing $<k_T^2>$ and fragmentation in exclusive $Q bar Q$ pair production. While these studies were done for $p+p$, $p + bar p$ and $p+$Pb collisions, understanding azimuthal angle correlations between heavy quarks in these smaller, colder systems is important for their interpretation in heavy-ion collisions. Methods: First, single inclusive $p_T$ distributions calculated with the exclusive HVQMNR code are compared to those calculated in the fixed-order next-to-leading logarithm approach. Next the azimuthal distributions are calculated and sensitivities to $<k_T^2>$, $p_T$ cut, and rapidity are studied at $sqrt{s} = 7$ TeV. Finally, calculations are compared to $Q bar Q$ data in elementary $p+p$ and $p + bar p$ collisions at $sqrt{s} = 7$ TeV and 1.96 TeV as well as to the nuclear modification factor $R_{p {rm Pb}}(p_T)$ in $p+$Pb collisions at $sqrt{s_{NN}} = 5.02$ TeV measured by ALICE. Results: The low $p_T$ ($p_T < 10$ GeV) azimuthal distributions are very sensitive to the $k_T$ broadening and rather insensitive to the fragmentation function. The NLO contributions can result in an enhancement at $phi sim 0$ absent any other effects. Agreement with the data was found to be good. Conclusions: The NLO calculations, assuming collinear factorization and introducing $k_T$ broadening, result in significant modifications of the azimuthal distribution at low $p_T$ which must be taken into account in calculations of these distributions in heavy-ion collisions.
It is shown that the spontaneous magnetization occurs due to the anomalous magnetic moments of quarks in the high-density quark matter under the tensor-type four-point interaction. The spin polarized condensate for each flavor of quark appears at high baryon density, which leads to the spontaneous magnetization due to the anomalous magnetic moments of quarks. The implications to the strong magnetic field in the compact stars is discussed.
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