$\bar{\mathrm{D}}$ and $\mathrm{B}$ mesons in nuclear medium

TL;DR

This paper investigates how $ar{ ext{D}}$ and $ ext{B}$ mesons' masses change in nuclear matter, showing they are bound due to negative mass shifts, and explores their energy levels in nuclei and effects in asymmetric media.

Contribution

It introduces a model for meson-nucleon interactions based on heavy quark symmetry and pion exchange, revealing mass shifts and binding properties of $ar{ ext{D}}$ and $ ext{B}$ mesons in nuclear medium.

Findings

$ar{ ext{D}}$ and $ ext{B}$ mesons experience negative mass shifts in nuclear medium.

$ar{ ext{D}}$ and $ ext{B}$ mesons are predicted to be bound within nuclei.

Large imaginary parts in $ar{ ext{D}}^{ ext{*}}$ and $ ext{B}^{ ext{*}}$ mesons hinder precise energy level studies.

Abstract

We discuss the mass modifications of $\bar{\mathrm{D}}$ and $\bar{\mathrm{D}}^{\ast}$ ($\mathrm{B}$ and $\mathrm{B}^{\ast}$) mesons in nuclear medium. The heavy quark symmetry for $\bar{\mathrm{D}}$ and $\bar{\mathrm{D}}^{\ast}$ ($\mathrm{B}$ and $\mathrm{B}^{\ast}$) mesons is adopted, and the interaction between a $\bar{\mathrm{D}}$ or $\bar{\mathrm{D}}^{\ast}$ ($\mathrm{B}$ or $\mathrm{B}^{\ast}$) meson and a nucleon is supplied from the pion exchange. We find the negative mass shifts for $\bar{\mathrm{D}}$ meson and $\mathrm{B}$ meson, and hence that the $\bar{\mathrm{D}}$ and $\mathrm{B}$ mesons are bound in the nuclear medium. As applications, we consider the atomic nuclei with a $\bar{\mathrm{D}}$ meson, $^{40}_{\bar{\mathrm{D}}}\mathrm{Ca}$ and $^{208}_{\bar{\mathrm{D}}}\mathrm{Pb}$, and investigate the energy levels of the $\bar{\mathrm{D}}$ meson in each nucleus. We also discuss the mass shifts in the isospin asymmetric nuclear medium, and present the possible phenomenon about distribution of isospin density around a $\bar{\mathrm{D}}$ or $\mathrm{B}$ meson in nuclear medium. We find that the mass shifts of $\bar{\mathrm{D}}^{\ast}$ and $\mathrm{B}^{\ast}$ mesons have large imaginary parts, which would prevent precise study of the energy levels of $\bar{\mathrm{D}}^{\ast}$ and $\mathrm{B}^{\ast}$ mesons in nuclei.