Dalitz decays $D_{sJ}^{(*)} \to D_s^{(*)} \ell^+ \ell^- $

TL;DR

This paper investigates the Dalitz decays of positive parity $D_{sJ}^{(*)}$ mesons to understand their nature, analyzing decay distributions and proposing measurements that can be performed with current experimental facilities.

Contribution

It provides a comprehensive analysis of $D_{sJ}^{(*)} o D_s^{(*)} \, \ell^+ \ell^-$ decays, relating observables through universal form factors and strong couplings, and discusses experimental feasibility.

Findings

Decay distributions depend on universal form factors.

Relations among observables in different decay modes.

Feasible measurements at current facilities.

Abstract

The Dalitz decays of the positive parity $D_{sJ}^{(*)}$ charmed mesons, $D_{sJ}^{(*)} \to D_s^{(*)} \ell^+ \ell^-$ with $J=0,1,2$ and $\ell=e, \mu$, are important processes to investigate the nature of the $D_{sJ}^{(*)}$ states. We analyze the full set of decays, considering the four lightest $D_{sJ}^{(*)}$ mesons as belonging to the heavy quark spin doublets $\displaystyle s_\ell^P=\frac{1}{2}^+$ and $\displaystyle \frac{3}{2}^+$, with $s_\ell^P$ the spin-parity of the light degrees of freedom in mesons. The description implies relations among the observables in various modes. We study the decay distributions in the dilepton invariant mass squared and the distributions in the angle between the charged lepton momentum and the momentum of the produced meson, which are expressed in terms of universal form factors and of effective strong couplings. Such measurements are feasible at the present facilities.