Searching for the $2^+$ partner of the $T_{cs0}(2870)$ in the $B^- \to D^- D^0 K^0_S$ reaction

TL;DR

This paper investigates a potential $2^+$ partner state of the $T_{cs0}(2870)$ in the $B^- o D^- D^0 K^0_S$ decay, proposing a method to enhance its detection through angular-moment analysis.

Contribution

It introduces a novel approach using angular-moment analysis to amplify the signal of a hypothesized exotic state in $B$ decay data.

Findings

Angular-moment spectra show a stronger signal than traditional mass distributions.

The method suggests a feasible way to identify the $2^+$ partner state.

Results encourage experimental evaluation of angular moments in current data.

Abstract

We study the $B^- \to D^- D^0 K^0_S$ reaction, recently analyzed by the LHCb collaboration, where a clear signal for the exotic $T_{cs0}(2870)$ state has been reported. We call the attention to a small peak in the $D^0 K^0_S$ mass distribution that could correspond to a state of the same nature as the $T_{cs0}(2870)$ ($D^* \bar K^*$ nature in the molecular picture) but with $J^P= 2^+$. In order to magnify the signal for the state, we calculate the moments of the angle-mass distribution, which are linear in the resonance signal, rather than quadratic for the angle integrated mass distribution. We find spectra for the moments with a strength far bigger than that for the angle integrated mass distribution, which should encourage the evaluation of these moments from the present measurements of the reaction.