Exotic $1^{--}$ States in QCD Sum Rules

TL;DR

This paper uses QCD sum rules to investigate the nature of exotic $1^{--}$ states like Y(4260), Y(4660), and Y_b(10890), proposing molecular and tetraquark interpretations based on calculated masses and current configurations.

Contribution

It introduces specific molecular and tetraquark current models for these states and calculates their masses, providing a theoretical interpretation consistent with experimental observations.

Findings

Y(4660) can be described as a $\\Psi(2S) f_0(980)$ molecular state.

Y_b(10890) is well described by a scalar-vector tetraquark current.

The calculated mass for the Y(4660) state is approximately 4.67 GeV.

Abstract

Using the QCD sum rules we test if the charmonium-like structure Y(4260), observed in the $J/\psi\pi\pi$ invariant mass spectrum, can be described with a $J/\psi f_0(980)$ molecular current with $J^{PC}=1^{--}$. We consider the contributions of condensates up to dimension six and we work at leading order in $\alpha_s$. We keep terms which are linear in the strange quark mass $m_s$. The mass obtained for such state is $m_{Y}=(4.67\pm 0.09)$ GeV, when the vector and scalar mesons are in color singlet configurations. We conclude that the proposed current can better describe the Y(4660) state that could be interpreted as a $\Psi(2S) f_0(980)$ molecular state. We also use different $J^{PC}=1^{--}$ currents to study the recently observed $Y_b(10890)$ state. Our findings indicate that the $Y_b(10890)$ can be well described by a scalar-vector tetraquark current.