Tetraquark states with open flavors

Liang Tang,Cong-Feng Qiao

doi:10.1140/epjc/s10052-016-4436-7

Abstract

In this work, we estimate the masses of tetraquark states with four different flavors by virtue of QCD sum rules, in both $b$ and $c$ sectors. We construct four $[8_c]_{\bar{b} s} \otimes [8_c]_{\bar{d} u}$ tetraquark currents with $J^P = 0^+$, and then perform analytic calculation up to dimension eight in the Operator Product Expansion (OPE). We keep terms which are linear in the strange quark mass $m_s$, and in the end find two possible tetraquark states with masses $(5.57 \pm 0.15)$ and $(5.58 \pm 0.15)$ GeV. We find that their charmed-partner masses lie in $(2.54 \pm 0.13)$ and $(2.55 \pm 0.13)$ GeV, respectively and are hence accessible in experiments like BESIII and Belle.

Highlights

The DØ Collaboration has reported the first observation of a narrow structure, called X (5568), in the decay chain φ→X (5568) → Bs0π ±, K + K − based on the Bs0 p p→ J/ψφ, J/ψ collision data at√→ s μ+μ−, = 1.96TeV collected at the Fermilab Tevatron collider [1]
In Ref. [8], the authors constructed a series of tetraquark currents to calculate the corresponding mass in the framework of quantum chromodynamics (QCD) sum rules, and their results support the X(5568) as a tetraquark state with quantum numbers J P = 0+ or 1+
We present the primary formulas of the QCD sum rules in Sect

Summary

Introduction

The DØ Collaboration has reported the first observation of a narrow structure, called X (5568), in the decay chain φ→. The authors investigated the X (5568) as a scalar tetraquark state using the approach of QCD sum rules [3,4,5,6,7]. [8], the authors constructed a series of tetraquark currents to calculate the corresponding mass in the framework of QCD sum rules, and their results support the X(5568) as a tetraquark state with quantum numbers J P = 0+ or 1+. We will construct four color-octet tetraquark currents, and we calculate their masses by means of QCD sum rules. 4. In this work, we study the color-octet tetraquark state with J P = 0+ via the approach of the QCD sum rules [17,18,19,20,21].

Numerical results

Summary