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 M eV , 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. Considerable decreasing in the values of the decay constants can be considered as a sign of the quark gluon plasma phase transition.

The thermal behavior of the spectroscopic parameters of the S-wave single heavy baryons * Q , * Q and * Q with spin-3/2 are investigated in QCD at finite temperature. We analyze the variations of the mass and residue of these baryons taking into consideration the contributions of QCD thermal condensates up to dimension eight in Wilson expansion. At finite temperature, due to the breakdown of the Lorentz invariance by the choice of reference frame and presence of an extra O(3) symmetry, some new four-dimensional operators come out in the form of the fermionic and gluonic parts of the energy momentum tensor that are taken into account in the calculations. Our analyses show that at lower temperatures, the parameters of baryons under consideration are not affected by the medium. These parameters, however, show rapid variations with respect to temperature at higher temperatures near to a pseudo-critical temperature, after which the baryons are melted. The results of the masses and residues at T → 0 limit are compatible with the available experimental data and predictions of other theoretical studies.

The thermal properties of f 2 (1270), a 2 (1320) and K * 2 (1430) light tensor mesons are investigated in the framework of QCD sum rules at finite temperature. In particular, the masses and decay constants of the light tensor mesons are calculated taking into account the new operators appearing at finite temperature. The numerical results show that at the point which the temperature-dependent continuum threshold vanishes, the decay constants decrease with amount of (70 − 85)% compared to their vacuum values, while the masses diminish about (60−72)% depending on the kinds of the mesons under consideration. The results obtained at zero temperature are in good consistency with the experimental data as well as existing theoretical predictions.

We investigate the masses and decay constants of the heavy-light D * 2 (2460) and D * s2 (2573) 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 D * 2 and D * s2 channels, respectively.

Motivated by the very recent discovery of the strange hidden-charm exotic state $$Z_{cs}(3985)$$ Z cs ( 3985 ) by the BESIII Collaboration, we study the possible interpretation of this exotic state the both at $$T=0$$ T = 0 and $$ T\ne 0 $$ T ≠ 0 . We analytically compute the mass and meson-current coupling constant of this resonance with spin-parity $$ J^{P} = 1^+$$ J P = 1 + at finite temperature approximation up to the sixth order of the thermal operator dimension including non-perturbative contributions. Extracting thermal mass and meson-current coupling constant sum rules, the modifications on properties of the $$Z_{cs}(3985)$$ Z cs ( 3985 ) state in hot medium are determined. As a by-product, the hadronic parameters of the bottom partner of $$Z_{cs}(3985)$$ Z cs ( 3985 ) is estimated as well. The search for temperature effects on the hadronic parameters of the hidden-charm meson $$Z_{cs}(3985)$$ Z cs ( 3985 ) and the bottom partner enable us to understand the phase transitions, chiral symmetry breaking, and the properties of hot-dense matter in QCD. Moreover, the full width of the resonance $$Z_{cs}(3985)$$ Z cs ( 3985 ) is calculated as $$(12.0\pm 0.8)~{\mathrm {MeV}}$$ ( 12.0 ± 0.8 ) MeV using the strong decay in the tetraquark picture. Results for width and mass are in reasonable agreement with existing experimental data and results of other theoretical works. The information obtained about the parameters of the considered states is useful for experimental investigations of exotic mesons.