Fully open-flavor tetraquark states bcbar{q}bar{s} and scbar{q}bar{b} with J^{P}=0^{+},1^{+}

Qi-Nan Wang,Wei Chen

doi:10.1140/epjc/s10052-020-7938-2

Abstract

We have studied the masses for fully open-flavor tetraquark states bcbar{q}bar{s} and scbar{q}bar{b} (q=u, d) with quantum numbers J^{P}=0^{+},1^{+}. We systematically construct all diquark–antiquark interpolating currents and calculate the two-point correlation functions and spectral densities in the framework of QCD sum rule method. Our calculations show that the masses are about 7.1-7.2 GeV for the bcbar{q}bar{s} tetraquark states and 7.0-7.1 GeV for the scbar{q}bar{b} tetraquarks. The masses of bcbar{q}bar{s} tetraquarks are below the thresholds of bar{B}_{s}D and bar{B}_{s}^{*}D final states for the scalar and axial-vector channels respectively. The scbar{q}bar{b} tetraquark states with J^{P}=1^{+} lie below the B_{c}^{+}K^{*} and B_{s}^{*}D thresholds. Such low masses for these possible tetraquark states indicate that they can only decay via weak interaction and thus are very narrow and stable.

Highlights

In the conventional quark model[1,2], hadrons generally have two kinds of structures: a meson consisting of a quark and an antiquark, and a baryon consisting of three quarks
We have investigated the mass spectra for the fully openflavored bcqsand scqbtetraquark states in the framework of quantum chromodynamics (QCD) sum rules
We find that the quark condensate qq and quark-gluon mixed condensate qgsσ ·Gq are proportional to the light quark mass and numerically small

Summary

Introduction

In the conventional quark model[1,2], hadrons generally have two kinds of structures: a meson consisting of a quark and an antiquark, and a baryon consisting of three quarks. [28], the non-strange fully open-flavor tetraquark states ucdband dcubhave been studied in the method of QCD sum rules. The above conflicting results from different phenomenological models are inspiring more theoretical studies for the existence of these fully open-flavor tetraquark states. We shall study the mass spectra of the fully open-flavor bcqsand scqbtetraquarks in the method of QCD sum rules [30,31]. To study the lowest lying bcqsand scqbtetraquark states, we use only S-wave diquarks and corresponding antidiquark fields to construct the tetraquark interpolating currents with quantum numbers J P = 0+, 1+. Η3μ = saT Cγ5cb qaγ μCbbT + qbγ μCbaT , η4μ = saT Cγ5cb qaγ μCbbT − qbγ μCbaT , in which the currents η1μ and η3μ are color symmetric while the η2μ and η4μ are color antisymmetric

QCD sum rules

Numerical analysis

Conclusion

The spectral densities for scqbtetraquarks