The chiral transitions in heavy-light mesons

TL;DR

This paper investigates mass shifts in heavy-light mesons due to chiral dynamics, predicting significant downward shifts and constraining mixing angles based on experimental data, using a parameter-free chiral quark-pion model.

Contribution

It provides a parameter-free calculation of mass shifts in heavy-light mesons due to chiral coupling, and constrains mixing angles with experimental limits.

Findings

Mass shifts of ~100-140 MeV for certain $D_s$ and $B_s$ mesons are predicted.

Masses of $B^*_s(0^+)$ and $B_s(1^{+'})$ are predicted close to known $B$ meson states.

Experimental width limits restrict the mixing angle between $1^+$ and $1^{+'}$ states.

Abstract

The mass shifts of the $P$-wave $D_s$ and $B_s$ mesons due to coupling to $DK$, $D^*K$ and $BK$, $B^*K$ channels are studied using the chiral quark-pion Lagrangian without fitting parameters. The strong mass shifts down $\sim 140$ MeV and $\sim 100$ MeV for $D^*_s(0^+)$ and $D_s(1^{+'})$ and $\sim 100$ MeV for $B^*_s(0^+)$ and $B_s(1^{+'})$ are calculated. Two factors are essential for large mass shifts: strong coupling of the $0^+$ and $1^{+'}$ states to the $S$-wave decay channel, containing a Nambu-Goldstone meson, and the chiral flip transitions due to the bispinor structure of both heavy-light mesons. The masses $M(B^*_s(0^+))=5695(10)$ MeV and $M(B_s(1^{+'}))=5730(15)$ MeV,very close to $M(B(0^+))$ and $M(B(1^{+'}))$, are predicted. Experimental limit on the width $\Gamma(D_{s1}(2536))<2.3$ MeV puts strong restrictions on admittable mixing angle between the $1^+$ and $1^{+'}$ states, $|\phi|<6^{\circ}$, which corresponds to the mixing angle $\theta$ between the $^3P_1$ and $^1P_1$ states, $29^{\circ}<\theta< 41^{\circ}$.