Investigation of heavy-heavy pseudoscalar mesons in thermal QCD Sum Rules

TL;DR

This study examines how the masses and decay constants of heavy-heavy pseudoscalar mesons change with temperature using finite temperature QCD sum rules, revealing significant reductions near the deconfinement point.

Contribution

It provides the first detailed analysis of temperature-dependent properties of $B_c$, $ar{c}c$, and $ar{b}b$ mesons within the finite temperature QCD sum rule framework, including nonperturbative effects.

Findings

Masses decrease by about 7%, 12%, and 2% at deconfinement temperature.

Decay constants reduce to approximately 35% of their vacuum values.

Results agree with experimental data and other theoretical approaches at zero temperature.

Abstract

We investigate the mass and decay constant of the heavy-heavy pseudoscalar, $B_c$, $\eta_c$ and $\eta_b$ mesons in the framework of finite temperature QCD sum rules. The annihilation and scattering parts of spectral density are calculated in the lowest order of perturbation theory. Taking into account the additional operators arising at finite temperature, the nonperturbative corrections are also evaluated. The masses and decay constants remain unchanged under $T\cong 100 ~MeV$, but after this point, they start to diminish with increasing the temperature. At critical or deconfinement temperature, the decay constants reach approximately to 35% of their values in the vacuum, while the masses are decreased about 7%, 12% and 2% for $B_c$, $\eta_c$ and $\eta_b$ states, respectively. The results at zero temperature are in a good consistency with the existing experimental values as well as predictions of the other nonperturbative approaches.