Evidence of the open-flavor tetraquark $T_{c\bar{s}2}$ in the process $B^+\to D^{*-}D_s^+\pi^+$

TL;DR

This paper presents evidence for a new open-flavor tetraquark state $T_{c\bar{s}2}$ in $B^+\to D^{*-}D_s^+\pi^+$ decays, based on a resonant structure observed in the $D_s^+\pi^+$ invariant mass distribution, and emphasizes the importance of angular distribution analysis for confirmation.

Contribution

The study predicts and provides experimental evidence for the $T_{c\bar{s}2}$ tetraquark, a spin partner of the previously observed $T_{c\bar{s}0}(2900)$, using invariant mass and angular distribution data.

Findings

Resonant-like structure around 2830 MeV in $D_s^+\pi^+$ mass distribution.

Angular momentum analysis shows distinct momentum patterns for different spin hypotheses.

Larger strength at the resonant energy in angular distribution than in integrated mass distribution.

Abstract

The newly observed open-flavor tetraquark $T_{c\bar{s}0}(2900)$ has attracted many attentions, and searching for its spin partners is crucial to exploring the internal structure of those states. In this work, we will show that, the $D_s^+\pi^+$ invariant mass distribution of the process $B^+\to D^{*-}D_s^+\pi^+$ measured by LHCb has a resonant-like structure around 2830~MeV, which could be associated with the predicted $T_{c\bar{s}2}$, the spin $J=2$ partner of $T_{c\bar{s}0}(2900)$. Furthermore, we have evaluated the momenta of the angular mass distribution, which are very different for each of the spin assumptions, and have larger strength at the resonant energy than the peaks seen in the angular integrated mass distribution. We make a call for the experimental determination of these magnitudes, which could be used to pin down the existence of the $T_{c\bar{s}2}$.