Electroweak properties of kaons in a nuclear medium

TL;DR

This paper investigates how kaon electroweak properties change in symmetric nuclear matter using the NJL model, revealing decreases in decay constants and increases in charge radius with rising nuclear density.

Contribution

It combines the NJL and quark-meson coupling models to study in-medium kaon properties, providing novel predictions on their density dependence.

Findings

Kaon decay constant decreases with nuclear density.

Kaon-quark coupling constant decreases with nuclear density.

$K^+$ charge radius increases by 20-25% at normal nuclear density.

Abstract

Kaon electroweak properties in symmetric nuclear matter are studied in the Nambu--Jona-Lasinio model using the proper-time regularization. The valence quark properties in symmetric nuclear matter are calculated in the quark-meson coupling model, and they are used as inputs for studying the in-medium kaon properties in the NJL model. We evaluate the kaon decay constant, kaon-quark coupling constant, and $K^+$ electromagnetic form factor by two different approaches. Namely, by two different ways of calculating the in-medium constituent quark masses of the light quarks. We predict that, in both approaches, the kaon decay constant and kaon-quark coupling constant decrease as nuclear density increases, while the $K^+$ charge radius increases by 20-25\% at normal nuclear density.