Vector and scalar mesons’ mixing from QCD sum rules

Abstract

We studyqq-hybrid mixing for the light vector mesons andqq-glueball mixing for the light scalar mesons in Monte-Carlo based QCD Laplace sum rules. By calculating the two-point correlation function of a vectorqγ µ q (scalarqq) current and a hybrid (glueball) current we are able to estimate the mass and the decay constants of the corresponding mixed "physical state" that couples to both currents. Our results do not support strong quark/gluonic mixing for either the 1 −− or the 0 ++ states.

Mixing of X and Y states from QCD Sum Rules analysis

“…By estimating the mass, coupling constants and taking into account experimental results, one can get insight into the constituent composition of the corresponding states. This method worked well in our previous study on vector and scalar meson states [14], and has been successfully applied in other systems [15][16][17].…”

“…Furthermore, the physical states are usually mixtures of different molecular structures, which makes the problem more complicated. In a previous study we have developed a method to estimate mixing strength of different currents from a QCD sum rule (QCDSR) approach [14][15][16][17], and we use the same technique to study the mixing of QqQq and QQqq XY states.…”

Mixing of X and Y states from QCD sum rules analysis *

“…However, and states QQ + qq Qq + Q q QqQ q QQ qq QqQ q QQ qq are difficult to distinguish straightforwardly from the decay modes of XYZ states because XYZ states are usually observed to have both like decay modes and like decay modes. Many scenarios were studied to qualitatively distinguish and states [10][11][12][13][14]. Furthermore, the physical states are usually mixtures of different structures, and this makes the problem more complicated.…”

“…As mentioned above, for the 1 ++ channel, has been extensively studied for a wide variety of structures [26,27]. In molecular state schemes, has been usually considered a molecular state [12][13][14]. However, although the pure molecular state was predicted to have a mass close to , it had too large a decay width to agree with the experimental results [28,29].…”