First exotic hadron with open heavy flavor: csu¯d¯ tetraquark

Marek Karliner,Jonathan L Rosner

doi:10.1103/physrevd.102.094016

Abstract

The LHCb Collaboration has reported resonant activity in the channel $D^+ K^-$, identifying two components: $X_0(2900)$ with $J^P = 0^+$ at $2866 {\pm} 7$ MeV, $\Gamma_0=57{\pm} 13$ MeV and $X_1(2900)$ with $J^P = 1^-$ at $2904 {\pm} 7$ MeV, $\Gamma_1=110{\pm} 12$ MeV. We interpret the $X_0(2900)$ component as a $cs \bar u\bar d$ isosinglet compact tetraquark, calculating its mass to be $2863 {\pm} 12$ MeV. This is the first exotic hadron with open heavy flavor. The analogous $bs\bar u\bar d$ tetraquark is predicted at $6213 {\pm} 12$ MeV. We discuss possible interpretations of the heavier and wider $X_1(2900)$ state and examine potential implications for other systems with two heavy quarks.

Highlights

Very recently, the LHCb Collaboration reported a narrow peak in the DþK− (þ charge conjugate) ( c:c:) channel as seen in the decay BÆ → DþD−KÆ
An obvious question is the interpretation of these states and whether their structure and properties can be elucidated with our current understanding of nonperturbative QCD
B quark results in a significant shift of the tetraquark mass vs the two-meson threshold. We have approached this problem using two different methods, both based on constituent quarks

Summary

Introduction

The LHCb Collaboration reported a narrow peak in the DþK− (þ charge conjugate) ( c:c:) channel as seen in the decay BÆ → DþD−KÆ. We compare the predictions of the string-junction picture with the baryonic-quark picture for the mass of a ground state JP 1⁄4 0þ tetraquark composed of csud , finding preference for the former in light of the new LHCb result [1]. The preferred string-junction method is applied to obtain the ground state mass of the exotic tetraquark bsud .

Results

Conclusion