Thermal Spectrum of Heavy Vector and Axial Vector Mesons in the Framework of QCD Sum Rules Method

TL;DR

This study calculates the thermal behavior of heavy vector and axial vector mesons' masses and decay constants using QCD sum rules, revealing their stability up to 100 MeV and significant reductions near the critical temperature.

Contribution

It introduces an improved thermal QCD sum rules approach accounting for additional operators and temperature-dependent continuum thresholds for heavy mesons.

Findings

Masses and decay constants are stable up to 100 MeV.

Masses decrease by up to 14-22% at critical temperature.

Decay constants reduce to less than 20% of vacuum values.

Abstract

The masses and the leptonic decay constants of vector and axial vector heavy-heavy mesons are calculated using the thermal QCD sum rules approach. While obtaining the QCD sum rules, additional operators in the Wilson expansion and also temperature dependency of the continuum threshold are taken into account. The masses and the decay constants remained unchanged up to $T\simeq100~MeV$. After that point, they start to diminish. At the critical temperature, the masses decreased about $3\%$, $5\%$ and $14\%$ for the vector mesons $\Upsilon$, $B_{c}$ and $J/\psi$; $6\%$, $7\%$ and $22\%$ for the axial vector mesons $\chi_{b1}$, $B_{c}$ and $\chi_{c1}$, respectively. The decay constants reached about less than $20\%$ of their vacuum values. The obtained results of the thermal mass and decay constant calculations at zero temperature are in a very good agreement with the other non-perturbative calculations at vacuum as well as with the experimental data.