Nucleon and hadron structure changes in the nuclear medium and the impact on observables

In-Medium $$\varvec{\rho }$$ ρ -Meson Properties in a Light-Front Approach

“…The QMC model, which describes nuclear matter based on the quark degrees of freedom, was introduced using MIT bag model by Guichon [23], and Frederico et al [24] with a confining harmonic potential. The model was successfully applied for finite nuclei [25], and also mesons properties in medium [26]. In the QMC model, because of the surrounding medium, the bound state mesons and baryons are modified, compared with those in vacuum.…”

“…Table 1 The MIT bag model (see Ref. [26] for details) quantities and coupling constants, the parameter ZN , bag constant B (in B 1/4 ), and the properties for symmetric nuclear matter at normal nuclear matter density ρ0 = 0.15 fm −3 , for mq = 5, 220 and mq = 430 MeV. The effective nucleon mass, m * N , and the nuclear incompressibility, K, are quoted in MeV (the free nucleon bag radius used is RN = 0.8 fm, the standard value in the QMC model [26]).…”

“…Next, the main ingredients of the QMC model are presented in order to calculate the ρ-meson properties in medium. For the system of a uniform, spin-and isospin-saturated symmetric nuclear matter, the effective Lagrangian density is given by [26],…”

“…Because of the symmetric nuclear matter in Hartree approximation, V q ρ is zero. The bag radius in medium for the ρ-meson, R * ρ , is determined by the stability condition for the mass of the hadron against the variation of the bag radius [26] (see Eq. (16)), and, the eigenenergies in units of 1/R * ρ are given by,…”

“…2 the calculated in-medium light-quark effective mass and the potentials (left panel), and the effective mass of the ρ-meson (right panel) in symmetric nuclear matter. In this study, the in-medium input calculated by the QMC model [26], namely, the effective constituent quark mass m * q and effective ρ-meson mass m * ρ , and the light-front model for the ρ-meson [9], are utilized in order to calculate the ρ-meson properties in symmetric nuclear matter.…”