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We generalize known results for heavy quarkonium in a thermal bath to the case of a finite baryonic density, and provide a number of formulas for the energy shift and decay width that hold at weak coupling for sufficiently large temperature and/or chemical potential. We find that a non-vanishing decay width requires a temperature larger than the typical binding energy, no matter how large the chemical potential is. This implies that at zero temperature the dissociation mechanism of heavy quarkonium is due entirely to screening, unlike in the finite temperature case. We use several effective theories in order to sort out the contributions of the relevant energy and momentum scales. In particular, we consider contributions of the so called quasi-static magnetic modes. The generalization to the case of a finite isospin/strangeness chemical potential is trivial. We discuss possible applications to the SIS and NICA conditions, and compare with available lattice results., Comment: 26 pages, 12 figures. v2: extended discussion, fixed typos. matched published version

We investigate the effect of strange quark degrees of freedom on the formation of inhomogeneous chiral condensates in a three-flavor Nambu--Jona-Lasinio model in mean-field approximation. A Ginzburg-Landau study complemented by a stability analysis allow us to determine in a general way the location of the critical and Lifshitz points, together with the phase boundary where the (partially) chirally restored phase becomes unstable against developing inhomogeneities, without resorting to specific assumptions on the shape of the chiral condensate. We discuss the resulting phase structure and study the influence of the bare strange-quark mass $m_s$ and the axial anomaly on the size and location of the inhomogeneous phase compared to the first-order transition associated with homogeneous matter. We find that, as a consequence of the axial anomaly, critical and Lifshitz point split. For realistic strange-quark masses the effect is however very small and becomes sizeable only for small values of $m_s$., Comment: 13 pages, 4 figures. v2: comments added, matches published version. Added plots data

We compute the damping rate of a fermion propagating in a chiral plasma when there is an imbalance between the densities of left- and right-handed fermions, after generalizing the hard thermal loop resummation techniques for these systems. In the ultradegenerate limit, for very high energies the damping rate of this external fermion approaches a constant value. Closer to the two Fermi surfaces, however, we find that the rate depends on both the energy and the chirality of the fermion, being higher for the predominant chirality. This comes out as a result of its scattering with the particles of the plasma, mediated by the exchange of Landau damped photons. In particular, we find that the chiral imbalance is responsible for a different propagation of the left and right circular polarised transverse modes of the photon, and that a chiral fermion interacts differently with these two transverse modes. We argue that spontaneous radiation of energetic fermions is kinematically forbidden, and discuss the time regime where our computation is valid., Comment: v2: extended version with more detailed analysis on dispersion relations and revised discussion on chiral plasma instability. Title modified. Version accepted for publication. v3: added missing piece in Eqs. (23)-(24), results and conclusions unchanged. 14 pages, 3 figures

We develop an innovative technique for studying inhomogeneous phases with a spontaneous broken symmetry. The method relies on the knowledge of the exact form of the free energy in the homogeneous phase and on a specific gradient expansion of the order parameter. We apply this method to quark matter at vanishing temperature and large chemical potential, which is expected to be relevant for astrophysical considerations. The method is remarkably reliable and fast as compared to performing the full numerical diagonalization of the quark Hamiltonian in momentum space, and is designed to improve the standard Ginzburg-Landau expansion close to the phase transition points. For definiteness we focus on inhomogeneous chiral symmetry breaking, accurately reproducing known results for 1D and 2D modulations and examining novel crystalline structures, as well. Consistently with previous results, we find that the energetically favored modulation is the so-called 1D real kink crystal. We propose a qualitative description of the pairing mechanism to motivate this result., 11 pages, 8 figures. v2 with minor changes. Accepted for publication on Physical Review D