# Pion structure in a nuclear medium

## TL;DR

This paper investigates how the internal structure and electroweak properties of the pion change within symmetric nuclear matter using the NJL model, revealing decreases in key parameters with increasing density.

## Contribution

It combines the NJL model with the quark-meson coupling model to analyze in-medium pion properties, providing new predictions on charge radius modifications.

## Key findings

- Light-quark condensates decrease with density
- Pion decay constant decreases in nuclear matter
- Charge radius of the pion increases in medium

## Abstract

The structure and electroweak properties of the pion in symmetric nuclear matter are presented in the framework of the Nambu--Jona-Lasinio model. The pion is described as a bound state of a dressed quark-antiquark pair governed by the Bethe-Salpeter equation. For the in-medium current-light-quark properties we use the quark-meson coupling model, which describes successfully the properties of hadron in a nuclear medium. We found that the light-quark condensates, the pion decay constant and pion-quark coupling constant decrease with increasing nuclear matter density. We then predict the modifications of the charge radius of the charged pion in nuclear matter.