E. Veli Veliev

Investigation of heavy-heavy pseudoscalar mesons in thermal QCD sum rules

We investigate the mass and decay constant of the heavy‐heavy pseudoscalar, Bc, ηc and ηb mesons in the framework of finite-temperature QCD sum rules. The annihilation and scattering parts of spectral density are calculated in the lowestorderofperturbationtheory.Takingintoaccounttheadditionaloperators arising at finite temperature, the nonperturbative corrections are also evaluated. The masses and decay constants remain unchanged under T ∼ 100 MeV, but after this point, they start to diminish with increasing temperature. At critical or deconfinement temperature, the decay constants reach approximately 35% of their values in vacuum, while the masses are decreased about 7%, 12% and 2% for Bc, ηc and ηb states, respectively. The results at zero temperature are in good consistency with the existing experimental values as well as predictions of the other nonperturbative approaches. (Some figures may appear in colour only in the online journal)

Thermal QCD sum rules study of vector charmonium and bottomonium states

We calculate the masses and leptonic decay constants of the heavy vector quarkonia, J/ψ and ϒ mesons at finite temperature. In particular, considering the thermal spectral density as well as additional operators coming up at finite temperature, the thermal QCD sum rules are acquired. Our numerical calculations demonstrate that the masses and decay constants are insensitive to the variation of temperature up to T ≅ 100 MeV, however after this point, they start to fall altering the temperature. At deconfinement temperature, the decay constants attain roughly to 45% of their vacuum values, while the masses are diminished about 12%, and 2.5% for J/ψ and ϒ states, respectively. The obtained results at zero temperature are in good consistency with the existing experimental data as well as predictions of the other nonperturbative models.

Thermal properties of

We investigate the masses and decay constants of the heavy–light and tensor mesons in the framework of thermal QCD sum rules. Taking into account the additional operators arising at finite temperature, we evaluate the Wilson expansion for the two-point correlation function associated with these mesons. We observe that the values of the masses and decay constants decrease considerably at near to the critical temperature. The decay constants attain roughly to 25% of their values in vacuum, while the masses decrease about 39% and 37% in and channels, respectively.

D_2^*(2460)

We investigate the thermal spectral densities for (pseudo)scalar and vector currents in the framework of the real time formalism when mass of two quarks are different. Such spectral densities are necessary for the phenomenological investigation of in-medium properties of hadrons. We use the quark propagator at finite temperature and calculate annihilation and scattering parts of spectral densities for above mentioned currents. The investigations show that the thermal contributions are significantly important. The obtained results at T → 0 limit are in good consistency with the vacuum results.

and

The strong form factor of the

tensor mesons using QCD sum rules

B_{c} B_{c}J/\Psi

B_c B_c J/\psi vertex form factor at finite temperature in the framework of QCD sum rules approach

BcBcJ/Ψ vertex is calculated in the framework of the QCD sum rules method at finite temperature. Taking into account additional operators appearing at finite temperature, a thermal Wilson expansion is obtained and QCD sum rules are derived. While increasing the temperature, the strong form factor remains unchanged up to