In-medium electromagnetic form factors of pseudoscalar mesons from the quark model

TL;DR

This study investigates how the electromagnetic form factors and charge radii of pseudoscalar mesons change in a nuclear medium, revealing significant modifications for light mesons and minimal effects on heavy-light mesons, emphasizing quark-level medium effects.

Contribution

It combines the light-front quark model with the quark-meson coupling model to systematically analyze in-medium electromagnetic form factors of mesons with various quark flavors.

Findings

EMFFs of charged mesons fall off faster with increasing density

Charge radii increase with nuclear density, depending on quark flavor

Light mesons are significantly modified, heavy-light mesons are minimally affected

Abstract

We explore the modifications of hadron structure in a nuclear medium, focusing on the spacelike electromagnetic form factors (EMFFs) of light and heavy-light pseudoscalar mesons. By combining the light-front quark model (LFQM) with the quark-meson coupling (QMC) model, which reasonably reproduces EMFFs in free space and the saturation properties of nuclear matter, respectively, we systematically analyze the in-medium EMFFs and charge radii of mesons with various quark flavors. Our findings show that the EMFFs of charged (neutral) mesons exhibit a faster fall-off (increase) with increasing four-momentum transfer squared and nuclear density. Consequently, the absolute value of the charge radii of mesons increases with nuclear density, where the rate of increase depends on their quark flavor contents. We observe that the EMFFs of pions and kaons undergo significant modifications in the nuclear medium, while heavy-light mesons are only slightly modified. By decomposing the quark flavor contributions to EMFFs, we show that the medium effects primarily impact the light-quark sector, leaving the heavy-quark sector nearly unaffected. The results of this study further suggest the importance of the medium effects at the quark level.