arXiv subjects

E. Veli Veliev

Publications and source records attributed to E. Veli Veliev.

At least 19 recordsLinked to original sources

arXiv2026

Temperature Effects on a Vector Hidden-Charm Molecule

We investigate the thermal properties of the $Y(4500)$ state within the framework of thermal QCD sum rules, assuming a $D_s \bar{D}_{s1}$ molecular configuration with $J^{PC}=1^{--}$. The analysis is performed at both zero and finite temperatures, employing the operator product expansion up to dimension-5 condensates. The Borel window and continuum threshold are carefully selected to ensure OPE convergence and pole dominance. As the temperature approaches the deconfinement temperature $T_c$, the $Y(4500)$ undergoes significant medium modifications: its mass decreases by $29\%$ and its decay constant is suppressed by $94\%$ relative to their vacuum values, while the decay width increases by $35\%$, signaling the dissociation of the state in the medium. These results indicate that the $Y(4500)$ becomes unstable near $T_c \approx 155~\mathrm{MeV}$, consistent with its melting into the quark-gluon plasma. The obtained thermal spectral parameters may serve as signatures for identifying the $Y(4500)$ in heavy-ion experiments at RHIC and LHC, and provide predictions for sequential suppression patterns in the exotic hadron sector.

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arXiv2026

Spectroscopic Properties of the Molecular $T_{cc}^{+}$ Meson in a Thermal Medium

In this work, we investigate the exotic doubly charmed molecular state $T_{cc}^{+}(3875)$ with quantum numbers $J^{P} = 1^{+}$ using the Thermal QCD Sum Rules framework. Employing a molecular interpolating current, we evaluate the two-point correlation function by incorporating non-perturbative condensate contributions up to dimension six. From the resulting thermal sum rules, we determine the temperature dependence of the mass, decay constant, and width of the $T_{cc}^{+}$ state. Our numerical analysis reveals that all quantities remain remarkably stable under temperature variations up to $T \simeq 120~\text{MeV}$, after which they change significantly. At the deconfinement temperature, the mass decreases to approximately $28\%$ of its vacuum value, and the decay constant drops to about $25\%$. We analyze the thermal evolution of the decay width of $T_{cc}^{+}$, finding $Γ_{T_{cc}^{+}}(0) = 434.95 \pm 7.66~\text{keV}$ at zero temperature. The width of $T_{cc}^{+}$ remains unchanged until $ T\simeq 120~\text{MeV}$, after which it begins to grow rapidly. The investigation of thermal effects on $T_{cc}^{+}$ provides new insights into QCD phase transitions, chiral symmetry restoration, and the properties of strongly interacting, hot, and dense matter. These findings are expected to serve as useful input for future experimental searches and phenomenological studies of exotic mesons.

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arXiv2025

Scalar fully-charm and bottom tetraquarks under extreme temperatures

Temperature dependences of masses and current couplings of the ground state of the fully heavy tetraquarks $T_{4c}$ and $T_{4b}$, composed of charm $(c)$ and bottom $(b)$ quarks and antiquarks with spin-parities $J^{PC} = 0^{++}$ are evaluated in the diquark antidiquark picture using Thermal QCD Sum Rules including vacuum condensates up to dimension four. The calculated values for $cc\bar{c}\bar{c}$ and $bb\bar{b}\bar{b}$ tetraquark states at $T=0$ align well with the experimental data on the broad structures. Based on the numerical analyses around the critical temperature, the mass of the $T_{4c}$ state decreases by $8\%$ compared to its vacuum state, while for its b partner, this percentage is approximately $3.3\%$. For the decay constants, the reductions are approximately $71\%$ and $66.6\%$, respectively. The precise exploration of tetraquark states awaits future scrutiny in upcoming experiments, including Belle II, Super-B, PANDA, and LHCb.

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arXiv2022

Dissociation of Pseudotensor Mesons through Critical Temperature

We have computed the masses and decay constants of isotriplet $π_2(1670)$, the isoscalar $η_2(1645)$ and $η_2(1870)$ states as the ground-state nonet of $1^1D_2$ case within the Thermal QCD sum rules framework. This method is applied to the spectral changes of pseudotensor mesons at high temperatures including quark, gluon, and mixed condensates up to the five dimensions. We found that their masses and decay constants are insensitive to temperature in low-temperature regions. At the near-critical temperature, we observed an exponential decrease of the masses of $π_2$, $η_2(1645)$, and $η_2(1870)$, but while the decay constant of $π_2$ is fallen, that of $η_2(1645)$ and $η_2(1870)$ is increased as a function of temperature. The modification of condensates at $T\neq 0$ is crucial to the change of considered mesons properties in a hot medium. We discuss and interpret the implications of the physical meaning of our results.

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arXiv2022

Impact of a thermal medium on newly observed $Z_{cs}(3985)$ resonance and its $ b $-partner

Motivated by the very recent discovery of the strange hidden-charm exotic state $Z_{cs}(3985)$ by the BESIII Collaboration, we study possible interpretation of this exotic state both at $ T= 0 $ and $ T\neq 0 $. We analytically compute the mass and meson-current coupling constant of this resonance with spin-parity $ J^{PC} = 1^{+-}$ at finite temperature approximation up to 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 $Z_{cs}(3985)$ state in hot medium is determined. As a by product, the hadronic parameters of the bottom partner of $Z_{cs}(3985)$ is estimated as well. Moreover the search of temperature effects on the hadronic parameters of hidden-charm meson $Z_{cs}(3985)$ and the bottom partner make us understand the phase transitions, chiral symmetry breaking and the properties of hot-dense matter in QCD.

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arXiv2021

Newly observed resonance $ X(4685) $: diquark-antidiquark picture

In this work, the mass and pole residue of $ X(4685) $ state with spin-parity $J^P=1^+$ are computed by the QCD sum rule approaches up to operator dimension seven based on the diquark-antidiquark configuration. For its mass we get $ m_{X_{cs}}= 4607^{+36}_{-22} $ MeV and pole residue $ λ_{X_{cs}}= 6.19^{+0.32}_{-0.24}\times 10^{-2}~\mathrm{GeV^5}$, which may be checked via other nonperturbative approaches as well as future experiments. As a by product, the mass of the hidden-bottom partner state of the $ X(4685) $ is extracted to be both around $ m_{X_{bs}}= (10604-10924) $ MeV and $ λ_{X_{bs}}= (42.2-53.7)\times 10^{-2}~\mathrm{GeV^5}$, which can be searched in the $Υϕ$ invariant mass distribution.

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arXiv2021

Modifications on the Properties of $D^*_{s0}(2317)$ as Four-quark State in Thermal Medium

Since the low mass of $D^*_{s0}(2317)$ has still been a problem to the conventional quark model, one can consider other options regarding as multi-quark system. Therefore we investigate the scalar open-charm state $D^*_{s0}(2317)$ by Thermal QCD Sum Rules (TQCDSR) method using the two-point correlation function together with contributions of the non-perturbative condensates up to dimension six. Deriving and numerically analyzing thermal mass and pole residue sum rules, we accomplish the effects on the properties of $D^*_{s0}(2317)$ resonance in hot medium. Our numerical evaluations indicate that the variations in mass and pole residue values are stable through the growing temperature up to $T\cong100~\mathrm{MeV}$, but they begin to fall after this point. At critical temperature, the values of mass and pole residue change up to $91\%, 70\% $ of their values in vacuum in the molecular scenario and $ 91\%, 69\% $ in the diquark-antidiquark scenario. Our results does not give any definite information as to whether $D^*_{s0}(2317)$ resonance has molecular or diquark-antidiquark structure since they are very close to each other to differentiate them. Besides, we predict the hadronic parameters of the bottom partner of the $D^*_{s0}(2317)$ resonance in both molecular and diquark-antidiquark pictures. This bound state is worth investigating in future experiments. Also the detailed search of hot medium effects on the hadronic parameters of open-charm meson $D^*_{s0}(2317)$ and the bottom partner could have some implications to define the QCD phase diagram obtained from heavy-ion collision experiments. Moreover these results can be useful in distinguishing conventional quark model mesons from exotica.

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arXiv2020

Missing Member of the $J^{PC} = 2^{--}$ Nonet in Extreme Conditions

The isoscalar member of the axial-tensor family that should take place in the further states of the PDG is still absent. In this study, analyzes are made as to whether one of the X states whose quantum numbers are unknown in this group, is a candidate for the missing resonance under the assignment $ 2^3D_2 $. Moreover, replacing the time evolution operator with the thermal average one, we construct the modified correlator satisfying Thermal QCD sum rules approach. We determine that the hadronic parameters of the considered nonet member are sensitive to the increment of temperature. This knowledge can be helpful to complete the $J^{PC} = 2^{--}$ light meson nonet and also explore the hot medium behaviors at upcoming heavy-ion collision experiments.

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arXiv2020

Axial-tensor Meson Family at $T\neq0$

The mass and decay constant of the axial-tensor meson nonets $ρ_2,~ω_2$ and a missing member and also their first excited states are analyzed by the Thermal QCD sum rules model including QCD condensates up to dimension five. Mass and decay constant values in terms of variations of temperature are very well stable from $T=0$ up to ~$T \cong 120 ~\mathrm{MeV}$. However nearly after these threshold, our numerical analysis indicate that they begin to diminish with increasing temperature. Mass value of these mesons and their first excited states decrease about $(1-13\%)$ compared to vacuum values and $(10-26\%)$ for the decay constants according to PDG data and $(9-26\%)$ and $(2-34\%)$ respectively concerning Regge Trajectory Model in the corresponding Thermal QCD sum rules calculations. The experimental results are already copious, but expected to grow up at ongoing and future heavy-ion experimental programs allowing us to compare our results.

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arXiv2019

In the Pursuit of $X(5568)$ and its Charmed Partner

The recent observation by the D$Ø$ collaboration of the first tetraquark candidate with four different quark flavors $(u, d, s$ and $ b)$ in the $B^0_sπ^{\pm}$ channel having a narrow structure, has still not been confirmed by other collaborations. Further independent experiments are required either to confirm the $X(5568)$ state or to set limits on its production. Though quantum numbers are not exactly clear, the results existing in the literature indicate that it is probably an axial-vector or scalar state candidate. In this study, mass and pole residue of the $X(5568)$ resonance assuming as a tightly bound diquark, with spin-parity both $J^{P}=1^{+}$ or $J^{PC}=0^{++}$ are calculated using two-point Thermal SVZ sum rules technique by including condensates up to dimension six. Moreover, its partner in the charm sector is also discussed. Investigations defining the thermal properties of $X(5568)$ and its charmed partner may provide valuable hints and information for the upcoming experiments such as CMS, LHCb and PANDA.

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arXiv2018

Hidden-Beauty Broad Resonance $Y_b(10890)$ in Thermal QCD

In this work, the mass and pole residue of resonance $Y_b$ is studied by using QCD sum rules approach at finite temperature. Resonance $Y_b$ is described by a diquark-antidiquark tetraquark current, and contributions to operator product expansion are calculated by including QCD condensates up to dimension six. Temperature dependences of the mass $m_{Y_b}$ and the pole residue $λ_{Y_b}$ are investigated. It is seen that near a critical temperature $(T_c\simeq190~\mathrm{MeV})$, the values of $m_{Y_b}$ and $λ_{Y_b}$ are decreased to $87\%$, and to $44\%$ of their values at vacuum.

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arXiv2018

Thermal properties of the exotic $X(3872)$ state via QCD sum rule

In this work we investigate the $X(3872)$ meson with quantum numbers $J^{PC}=1^{++}$ in the framework of the thermal QCD sum rules method. We use a diquark-antidiquark current with the corresponding quantum numbers and calculate the two-point correlation function including contributions of non-perturbative condensates up to six dimensions. Analysis of the obtained thermal sum rule allows us to study contributions of a medium to the mass and coupling constant of the $X(3872)$ resonance. Our numerical calculations demonstrate that the mass and the meson-current coupling constant are insensitive to the variation of temperature up to $T=110\sim MeV$ , however after this point; they start to fall by increasing the temperature. At deconfinement temperature, the meson-current coupling constants attain roughly to $34\%$ of the vacuum value.

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arXiv2016

$ B_c B_c J/ψ$ Vertex Form Factor at Finite Temperature in the Framework of QCD Sum Rules Approach

The strong form factor of the $B_{c} B_{c}J/Ψ$ vertex is calculated in the framework of the QCD sum rules method at finite temperature. Taking into account additional operators appearing at finite temperature, thermal Wilson expansion is obtained and QCD sum rules are derived. While increasing temperature, the strong form factor remains unchanged up to $T\simeq100~MeV$ but slightly increases after this point. After $T\simeq160~MeV$, the form factor suddenly decreases up to $T\simeq170~MeV$. The obtained result of the coupling constant by fitting the form factor at $Q^2=-m^2_{offshell}$ at $T=0$ is in a very good agreement with the QCD sum rules calculations at vacuum. Our prediction can be checked in the future experiments.

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arXiv2015

Thermal properties of light tensor mesons via QCD sum rules

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.

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arXiv2015

Thermal behaviors of light unflavored tensor mesons in the framework of QCD sum rule

In this study, we investigate the sensitivity of the masses and decay constants of the light $f_{2}(1270)$ and $a_{2}(1320)$ tensor mesons to the temperature using QCD sum rule approach. In our calculations, we take into account the additional operators appearing in operator product expansion at finite temperature. It is obtained that at deconfinement temperature the decay constants and masses decrease with amount of $6\%$ and $96\%$ compared to their vacuum values, respectively. Our results on the masses at zero temperature are consistent with the vacuum sum rules predictions as well as the experimental data.

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arXiv2014

Thermal properties of $D_2^(2460)$ and $D_{s2}^(2573)$ tensor mesons using QCD sum rules

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.

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arXiv2013

Investigation of the $D^{\ast}_{s}D_{s} η^{(\prime)}$ and $B^{\ast}_{s}B_{s} η^{(\prime)}$ vertices via QCD sum rules

The strong coupling constants among mesons are very important quantities as they can provide useful information on the nature of strong interaction among hadrons as well as the QCD vacuum. In this article, we investigate the strong vertices of the $D^{\ast}_{s}D_{s} η^{(\prime)}$ and $B^{\ast}_{s}B_{s} η^{(\prime)}$ in the framework of the QCD sum rule approach choosing the $η$ or $D_{s} (B_{s})$ meson as an off-shell state. We obtain the results $g_{D_s^*D_sη}=(1.46\pm 0.30)GeV^{-1}$, $g_{D_s^*D_sη^{\prime}}=(0.74\pm 0.16)GeV^{-1}$, $g_{B_s^*B_sη}=(5.29\pm 1.06)GeV^{-1}$ and $g_{B_s^*B_sη^{\prime}}=(2.29\pm 0.48)GeV^{-1}$ for the strong coupling constants under consideration, which can be checked in future experiments.

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arXiv2012

Spectrum of the heavy axial vector χ_b1(1P) and χ_c1(1P) mesons in thermal QCD

Using the additional operators coming up at finite temperature, we calculate the masses and decay constants of the P wave heavy axial-vector χ_b1 and χ_c1 quarkonia in the framework of thermal QCD sum rules. In the calculations, we take into account the perturbative two loop order alpha_s corrections and nonperturbative effects up to the dimension four condensates. It is observed that the masses and decay constants almost remain unchanged with respect to the variation of the temperature up to T \simeq 100 MeV, however after this point, the decay constants decrease sharply and approach approximately to zero at critical temperature. The decreasing in values of the masses is also considerable after T \simeq 100 MeV .

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