Spectroscopy of $ρ$-meson in symmetric nuclear medium

TL;DR

This work addresses how the vector $ρ$ meson properties change in symmetric nuclear matter at zero temperature. It uses a hybrid approach where the vacuum structure is modeled with a light-front quark model (LFQM) and medium effects are introduced via the chiral SU(3) quark mean-field (CQMF) model, yielding density-dependent quark masses and fields. The study reports density-induced shifts in the $ρ$ mass and weak decay constant, medium-modified distribution amplitudes and their LO ERBL evolution, as well as in-medium electromagnetic form factors (charge, magnetic, quadrupole) and derived observables such as charge radii, magnetic moments, and quadrupole moments. Overall, the medium induces sizable changes in mass, decay constant, DAs, and widths while charge radii and magnetic/quadrupole moments show weaker sensitivity up to several times nuclear saturation density. The results advance understanding of in-medium QCD dynamics and offer insights relevant for dilepton experiments and chiral restoration in dense matter, with consistency checks against lattice and ILM findings.

Abstract

In this work, we investigate the behavior of the light vector \(ρ\) meson in the presence of a symmetric nuclear medium at zero temperature. We calculate the mass and decay constant of the $ρ$-meson as well as the leading twist distribution amplitudes (DAs) in the light-front quark model in vacuum, which are further investigated at different baryonic densities. We also predict the Mellin moments of the DAs and decay width of the $ρ^0 \to e^+ e^-$ process in both vacuum and medium. The evolution of DAs is carried out by the leading order (LO) Efremov-Radyushkin-Brodsky-Lepage method and compared with available predictions. For better understanding of medium effects on $ρ$-meson, we have also predicted the in-medium charge ($G_C(Q^2)$), magnetic ($G_M(Q^2)$), and quadrupole ($G_Q(Q^2)$) form factors. The in-medium charge radii, magnetic moment, and quadrupole moment have also been predicted in this work. We have found that the nuclear medium induces appreciable modifications on the mass, weak decay constant, decay width, and distribution amplitudes of the \(ρ\) meson. However, the charge radii, magnetic moment, and quadrupole moment are observed to exhibit weaker sensitivity to changes in baryonic density.

Figures (9)

• Figure 1: Effective mass of $\rho$ meson as a function of baryon density $\rho_B$ (in units of nuclear saturation density $\rho_0$). Results are shown both with and without the contribution of the hyperfine potential.
• Figure 2: (Color line)The in-medium $\rho$ meson decay constant (in units of GeV) has been plotted with baryonic density $\rho_B/\rho_0$ for both longitudinal and transverse components in the left panel. The ratio of in-medium and vacuum decay constant for both longitudinal and transverse polarization has been plotted with respect to baryonic density $\rho_B/\rho_0$ in the right panel.
• Figure 3: (Color line) The in-medium and normalized decay width of $\rho$ meson have been plotted with respect to baryonic density $\rho_B/\rho_0$ in units of keV in the left and right panel, respectively.
• Figure 4: (Color line) The in-medium longitudinal distribution amplitude has been plotted with respect to baryonic density $\rho_B/\rho_0$ in the interval of 0.25 in the left panel and in the interval of 1 in the right panel, respectively.
• Figure 5: The in-medium transverse distribution amplitude has been plotted with respect to baryonic density $\rho_B/\rho_0$ in the interval of 0.25 in the left panel and in the interval of 1 in the right panel, respectively