arXiv subjects

K. Azizi

Publications and source records attributed to K. Azizi.

At least 127 records · Page 7Linked to original sources

arXiv2023

Investigation of a candidate spin-$\frac{1}{2}$ hidden-charm triple strange pentaquark state $P_{csss}$

A candidate triple strange pentaquark state, $P_{csss}$, is investigated through its strong decay channel $P_{csss} \rightarrow Ω^-J/ψ$. To calculate the relevant strong coupling constants, two possible interpolating currents with spin-parity $J^P=\frac{1}{2}^{-}$ are used. Though the chosen currents for the state under consideration have spin-parity quantum numbers $J^P=\frac{1}{2}^{-}$, they couple to both the positive and negative parity states simultaneously and the corresponding decay widths are obtained for both parities. These widths are obtained as $Γ(P_{csss} \rightarrow J/ψΩ^-)=201.4\pm 82.5~\mathrm{MeV}$ for the negative and $Γ(\widetilde{P}_{csss} \rightarrow J/ψΩ^-)=316.4\pm 107.8~\mathrm{MeV}$ for the positive parity state when the first current is used. For the second current, we obtain $Γ(P_{csss} \rightarrow J/ψΩ^-)=252.5\pm 116.7~\mathrm{MeV}$ for the negative and $Γ(\widetilde{P}_{csss} \rightarrow J/ψΩ^-)=361.1\pm 98.4~\mathrm{MeV}$ for the positive parity state. These results may provide insights into future experimental observations of such candidate states and help to distinguish and fix their properties.

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arXiv2022

Heavy-light hybrid mesons with different spin-parities

The spectroscopic parameters of the heavy-light hybrid mesons with different spin-parities and different quark contents are investigated in the framework of the QCD sum rule method. The mass and current coupling of these states are calculated by taking into account the quark, gluon and mixed vacuum condensates up to dimension 10. The obtained results are compared with the existing QCD Laplace sum rule predictions. The results of mass and current coupling for all the considered channels are obtained to be stable and reliable. Our results can be useful for future experimental searches as well as theoretical studies of different parameters related to the hybrid mesons and their decays and interactions with other particles.

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arXiv2022

Interpretation of the $Λ_c(2910)^+$ baryon newly seen by Belle Collaboration and its possible bottom partner

The developments in the experimental facilities and analyses techniques have recently lead to the observation of many hadronic states ranging from excitations of conventional hadrons to various exotic states. The baryons with single heavy quark are among these states providing an attractive field of research to get a better understanding of the nonperturbative nature of the strong interaction. Recently, the Belle Collaboration announced observation of the state $Λ_c(2910)^+$ with a mass $2913.8\pm5.6\pm3.8~\mathrm{MeV}/c^2$ and width $51.8\pm20.0\pm18.8~\mathrm{MeV}$. In the present study, by the mass analyses of different excitations at $Λ_c$ channel and their comparison with existing experimental information, we find that the spin-parity of this newly found excited state is $ J^P= \frac{1}{2}^-$ and it is a $ 2P $ state denoting by $Λ_c(\frac{1}{2}^-,2P)$. We predict its current coupling as well, which can be served as one of the main input parameters to investigate different decays and interactions of this particle. We also determine the mass and current coupling of $Λ_b(\frac{1}{2}^-,2P)$ as possible bottom counterpart of the new $Λ_c(2910)^+$ state, which may be in agenda of different experiments in near future.

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arXiv2022

Is the resonance $X_0(2900)$ a ground-state or radially excited scalar tetraquark $[ud][\overline{c}\overline{s}]$?

We investigate properties of the ground-state and first radially excited four-quark mesons $X_0$ and $X_0^{\prime}$ with a diquark-antidiquark structure $[ud][\overline{c}\overline{s}]$ and spin-parities $J^{\mathrm{P} }=0^{+}$. Our aim is to reveal whether or not one of these states can be identified with the resonance $X_0(2900)$, recently discovered by the LHCb collaboration. We model $X_0$ and $X_0^{\prime}$ as tetraquarks composed of either axial-vector or scalar diquark and antidiquark pairs. Their spectroscopic parameters are computed by employing the QCD two-point sum rule method and including into analysis vacuum condensates up to dimension $ 15$. For an axial-axial structure of $X_0^{(\prime)}$, we find partial widths of the decays $X_0^{(\prime)} \to D^{-}K^{+}$ and $X_0^{(\prime)} \to D^{0}K^{0}$, and estimate full widths of the states $X_0^{(\prime)}$. To this end, we calculate the strong couplings at the vertices $ X_0^{(\prime)}DK $ in the framework of the light-cone sum rule method. We use also technical approaches of the soft-meson approximation necessary to analyze tetraquark-meson-meson vertices. Obtained results $m=(2545 \pm 160)~ \mathrm{MeV}$ and $m^{\prime}=(3320 \pm 120)~\mathrm{MeV}$ [$m_{\mathrm{S} }=(2663 \pm 110)~\mathrm{MeV}$ and $m_{\mathrm{S}}^{\prime}=(3325 \pm 85)~ \mathrm{MeV}$ for a scalar-scalar current] for the masses of the particles $ X_0$ and $X_0^{\prime}$, as well as estimates for their full widths $ Γ_{0}=(140 \pm 29)~\mathrm{MeV}$ and $Γ_{0}^{\prime}=(110 \pm 25)~ \mathrm{MeV}$ allow us to interpret none of them as the resonance $X_0(2900)$ . At the same time, these predictions provide important information about ground-state and radially excited diquark-antidiquark structures $X_0$ and $ X_0^{\prime}$, which should be objects of future experimental and theoretical studies.

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arXiv2022

Resonance $X(4630)$

We investigate the structure $X(4630)$ discovered by the LHCb collaboration in the process $B^{+}\rightarrow J/ψϕK^{+}$ as a resonance in the $ J/ψϕ$ mass distribution. We explore this resonance as a diquark-antidiquark state $X=[cs][\overline{c}\overline{s}]$ with spin-parities $J^{\mathrm{PC}}=1^{-+}$. Its mass and current coupling are calculated using the QCD two-point sum rule method by taking into account vacuum condensates up to dimension $10$. We also study decays of this tetraquark to mesons $J/ψϕ$, $η_{c}η^{(\prime )}$, and $χ_{c1}η^{(\prime )}$, and compute partial widths of these channels. To this end, we employ the light-cone sum rule approach and technical methods of soft-meson approximation to extract strong coupling at relevant tetraquark-meson-meson vertices. Our predictions for the mass $m=(4632\pm 60)~\mathrm{MeV}$ and width $Γ=(159\pm 31)~\mathrm{MeV}$ of $X$ are in a very nice agreement with recent measurements of the LHCb collaboration. These results allow us to interpret the resonance $X(4630)$ as the tetraquark $X$ with spin-parities $J^{\mathrm{PC}}=1^{-+}$.

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arXiv2022

Magnetic moment of the $X_1(2900)$ state in the diquark-antidiquark picture

Motivated by the discovery of fully open-flavor tetraquark states $X_0(2900)$ and $X_1(2900)$ by the LHCb Collaboration, the magnetic dipole moment of the $X_1(2900)$ state with the quantum numbers $ J^{P} = 1^{-}$ is determined in the diquark-antidiquark picture using the light-cone sum rules. The numerical result is obtained as $ μ_{X_1}=0.79^{+0.36}_{-0.39}\,μ_N$. The magnetic moments of hadrons encompasses useful knowledge on the distributions of charge and magnetization their inside, which can be used to better understand their geometrical shapes and quark-gluon organizations. The observation of the $X_0(2900)$ and $X_1(2900)$ as the first two fully open-flavor multiquark states has opened a new window for investigation of the exotic states. The obtained results in the present study may shed light on the future experimental and theoretical searches on the properties of fully open-flavor multiquark states.

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arXiv2022

Investigation of hidden-charm double strange pentaquark candidate $P_{css}$ via its mass and strong decays

This work presents an analysis of a hidden charmed pentaquark candidate state with double strange quark in its quark content. The investigation is performed in two parts, which provide the mass prediction of the considered state and its partial decay widths for the $P_{css}\rightarrow Ξ^0 J/ψ$ and $P_{css}\rightarrow Ξ_c^+ D_s^-$ channels. For the analyses, two-point and three-point QCD sum rule methods are applied to get the mass and the widths, respectively. The mass for this candidate state is obtained as $m_{P_{css}}=4600 \pm 155$ MeV with corresponding current coupling constant $λ_{P_{css}}=(0.81 \pm 0.21)\times 10^{-3}$ GeV$^6$. These results are used in the analysis of the partial widths of this state for the decays $P_{css}\rightarrow Ξ^0 J/ψ$ and $P_{css}\rightarrow Ξ_c^+ D_s^-$. From these decays, the total width is obtained as $Γ= 12.29\pm 2.94 $ MeV. These results may shed light on the future experimental searches in which such types of states are probed and may provide information to discriminate between such possible observations.

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arXiv2022

Hadronic molecule model for the doubly charmed state $T^{+}_{cc}$

The mass, current coupling, and width of the doubly charmed four-quark meson $T_{cc}^{+}$ are explored by treating it as a hadronic molecule $ M_{cc}^{+}\equiv D^{0}D^{\ast +}$. The mass and current coupling of this molecule are calculated using the QCD two-point sum rule method by including into analysis contributions of various vacuum condensates up to dimension $ 10 $. The prediction for the mass $m=(4060\pm 130)~\mathrm{MeV}$ exceeds the two-meson $D^{0}D^{\ast +}$ threshold $3875.1~\mathrm{MeV}$, which makes decay of the molecule $M_{cc}^{+}$ to a pair of conventional mesons $ D^{0}D^{\ast +}$ kinematically allowed process. The strong coupling $G $ of particles at the vertex $M_{cc}^{+}D^{0}D^{\ast +}$ is found by applying the QCD three-point sum rule approach, and used to evaluate the width of the decay $M_{cc}^{+} \to D^{0}D^{\ast +}$. Obtained result for the width $ Γ=(3.8\pm 1.7)~\mathrm{MeV}$ demonstrates that $M_{cc}^{+}$ is wider than the resonance $T_{cc}^{+}$.

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arXiv2022

Investigation of $Δ^0Δ^0$ dibaryon in QCD

We study a hypothetical $Δ^0Δ^0$ dibaryon state by means of QCD sum rule method. We construct a scalar interpolating current to extract the mass and decay constant of this state taking into account contributions of various quark, gluon and mixed vacuum condensates. The predictions for the mass and decay constants are $m_D=2326^{+114}_{-126} ~\mathrm{MeV}$ and $f_D=2.94^{+0.30}_{-0.34}\times 10^{-4} ~\mathrm{GeV}^7$, respectively. We also made an estimation about binding energy and size of the $Δ^0Δ^0$ dibaryon. The obtained mass value is below the $Δ^0Δ^0$ threshold and may be a good dibaryon candidate for being observed experimentally.

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arXiv2022

Spectroscopic parameters and electromagnetic form factor of kaon in vacuum and a dense medium

The spectroscopic parameters as well as electromagnetic form factor of the strange particle kaon are investigated in vacuum and a medium with finite density. The obtained vacuum mass and decay constant, which are consistent with the existing experimental results, are used to extract the $ Q^2 $ dependence of the kaon electromagnetic form factor in the interval $Q^2\in [0,10]$ GeV$^2$ in vacuum. The obtained results at lower and intermediate values of $ Q^2 $ are consistent with the existing experimental data within the presented uncertainties. The $ Q^2 $ behavior of the electromagnetic form factor of kaon in vacuum and in the interval $Q^2\in [0,6]$ GeV$^2$ is in a nice agreement with the existing predictions of the Lattice QCD and the solution of the Bethe-Salpeter equation for the model of Nambu and Jona-Lasinio (NJL) with proper-time regularization, as well. The obtained vacuum radius for kaon is also in a nice agreement with the world's average experimental result. We extend the analyses to a medium with higher densities and obtain the behavior of the mass, decay constant, electromagnetic form factor and radius with respect to density. The obtained results for some of the parameters are compared with the existing predictions of other models and approaches. The results obtained in the present study can be useful for future experimental and theoretical studies both in vacuum and a dense medium.

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arXiv2022

Determination of the generalized parton distributions through the analysis of the world electron scattering data considering two-photon exchange corrections

We determine the valence generalized parton distributions (GPDs) $ H_v^q $ and $ E_v^q $ with their uncertainties at zero skewness by performing a $ χ^2 $ analysis of the world electron scattering data considering two-photon exchange corrections. The data include a wide and updated range of the electric and magnetic form factors (FFs) of the proton and neutron. As a result, we find that there are no enough constraints on GPDs $ E_v^q $ from FFs data solely though $ H_v^q $ are well constrained. By including the new data of the charge and magnetic radius of the nucleon in the analysis, we show that they put new constraints on the final GPDs, especially on $ E_v^q $. Moreover, we calculate the gravitational FF $ M_2 $ and the total angular momentum $ J^q $ using the extracted GPDs and compare them with the FFs obtained from the light-cone QCD sum rules (LCSR) and Lattice QCD. We show that our results are interestingly in a good consistency with the pure theoretical predictions.

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arXiv2022

Radiative $Ξ_{b}^{-}\rightarrow Ξ^{-}γ$ decay

Recently, the LHCb Collaboration performed first search for the rare radiative $Ξ_{b}^{-}\rightarrow Ξ^{-}γ$ decay and put an upper limit, ${\cal B}(Ξ_{b}^{-}\to Ξ^{-}γ) < 1.3 \times 10^{-4}$, on its branching ratio. The measurement agrees well with existing theory prediction using SU(3) flavor symmetry method, but shows a slight tension with the previous prediction from light-cone sum rules. Inspired by this, we investigate this decay as well as other radiative decays of $Ξ_b^{0(-)}(Ξ^{'-}_{b})$ to $Ξ^{0(-)}$ and $Σ^{0(-)}$ baryons using the form factors calculated from light-cone QCD sum rules in full theory. we obtain $ {\cal B}(Ξ_{b}^{-}\to Ξ^{-}γ)=1.08^{+0.63}_{-0.49} \times 10^{-5} $, which lies below the upper limit set by LHCb and is consistent with flavor-symmetry driven prediction. Our predictions on other channels may be checked in experiment and by other phenomenological approaches.

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arXiv2022

Newly observed exotic doubly charmed meson $T^{+}_{cc}$

In this work, we treat the newly observed doubly charmed four-quark state $ T_{cc}^{+}$ as an axial-vector tetraquark with content $cc\overline{u} \overline{d}$, and calculate its spectroscopic parameters and width. The mass and current coupling of the tetraquark $T_{cc}^{+}$ are found by means of the QCD two-point sum rule method by taking into account quark, gluon and mixed condensates up to dimension $10$. The width of the $T_{cc}^{+}$ is evaluated using partial widths of decay processes $T_{cc}^{+} \to \widetilde{ T}π^{0}$ and $T_{cc}^{+} \to T_{cc;\overline{u}\overline{u}}^{0}π^{+}$ , where $\widetilde{T}=cc\overline{u}\overline{d}$ and $T_{cc;\overline{u} \overline{u}}^{0}$ are scalar tetraquarks. To compute the partial width of the first process, we apply the QCD three-point sum rule approach and extract numerical value of the strong coupling $g$ that corresponds to the vertex $T_{cc}^{+}\widetilde{T}π^{0}$. The width of the second decay is estimated using isospin symmetry and the prediction obtained for the first channel. Our results for the mass $m=(3868\pm 124)~\mathrm{MeV}$ and width $ Γ=(489\pm 92)~\mathrm{keV}$ of the tetraquark $T_{cc}^{+}$ are in a nice agreement with recent measurements of the LHCb collaboration.

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arXiv2021

Magnetic dipole moments of the $T_{cc}^+$ and $Z_V^{++}$ tetraquark states

Inspired by the observation of the doubly charmed state $T_{cc}$ and following theoretical studies on its spectroscopic parameters, we investigate its magnetic dipole moment assigning it the quantum numbers $J^P=1^+$ and both the compact diquark-antidiquark and molecular structures in the framework of the light-cone QCD. We also calculate the magnetic dipole moment of the theoretically predicted singly charmed state, $Z_V^{++}$, with two units of electric charge and the quantum numbers $J^P=1^-$ in diquark-antidiquark picture. The numerical results are obtained as $μ_{T_{cc}^+-Di} =0.66^{+0.34}_{-0.23}~μ_N$, $ μ_{T_{cc}^+-Mol} =0.43^{+0.23}_{-0.22}~μ_N $ and $μ_{Z_{V}^{++}} =3.35^{+0.89}_{-0.73} ~μ_N$. These results may be checked via other phenomenological approaches. The obtained results may be useful in exact determinations of the natures of these states.

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arXiv2021

Properties of spin-1/2 heavy baryons at nonzero temperature

The spectroscopic properties of single heavy spin-1/2 $Λ_{Q}$, $Σ_{Q}$, $Ξ^{(\prime)}_{Q}$ and $ Ω_{Q}$ baryons are investigated at finite temperature in the framework of thermal QCD sum rule. We discuss the behavior of the mass and residue of these baryons with respect to temperature taking into account contributions of non-perturbative operators up to dimension eight. We include additional operators coming from the Wilson expansion due to breaking the Lorentz invariance at non-zero temperature. The obtained results show that the mass of these baryons remain stable up to roughly $T=108$ MeV while their residue are unchanged up to $T=93$ MeV. After these points, the mass and residue start to diminish by increasing the temperature. The shifts in the mass and residue for both the bottom and charm channels are considerably large and we observe the melting of these baryons near to the pseudo-critical temperature determined by recent lattice QCD calculations. We present our results for the mass of these baryons with both the positive and negative parity at $ T\rightarrow 0 $ limit, which are consistent with the existing theoretical predictions as well as experimental data.

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arXiv2021

Magnetic dipole moment of the $Z_{cs}(3985)$ state: diquark-antidiquark and molecular pictures

We calculate the magnetic dipole moment of the newly observed charged hidden-charmed open strange $ Z_{cs}(3985)^- $ state, recently observed by BESIII Collaboration. Based on the information provided by the experiment and theoretical studies followed the observation, we assign the quantum numbers $ J^{P} = 1^{+}$ and the quark composition $ c \bar c s\bar u $ to this state and estimate the magnetic dipole moment of this resonance in both the compact diquark-antidiquark and molecular pictures. We apply the light cone QCD formalism and use the distribution amplitudes of the on-shell photon with different twists. The obtained results in both pictures are consistent with each other within the errors. The magnitude of the magnetic dipole moment shows that it is accessible in the experiment.

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arXiv2021

Strong Vertices of Doubly Heavy Spin-3/2 Baryons with Light Pseudoscalar Mesons

The strong coupling constants are basic quantities that carry information of the strong interactions among the baryon and meson multiplets as well as information on the natures and internal structures of the involved hadrons. These parameters enter to the transition matrix elements of various decays as main inputs and they play key roles in analyses of the experimental data including various hadrons. We determine the strong coupling constants among the doubly heavy spin-$ 3/2 $ baryons, $Ξ^*_{QQ'} $ and $Ω^*_{QQ'}$, and light pseudoscalar mesons, $π$, $K$ and $η$, using the light-cone QCD. The values obtained for the strong coupling constants under study may be used in construction of the strong potentials among the doubly heavy spin-3/2 baryons and light pseudoscalar mesons.

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arXiv2021

Gravitational form factors of $N(1535)$ in QCD

We calculate the gravitational form factors of the excited $N(1535)$ state with the quantum numbers $I(J^P)=\frac{1}{2}(\frac{1}{2}^-)$ via light cone QCD sum rules (LCSR). To this end, we consider the quark part of the energy-momentum tensor (EMT) current and use the general form of the nucleon's interpolating field as well as the distribution amplitudes (DAs) of $N(1535)$. As both the nucleon and $N(1535)$ couple to the same current, the $N(1535) \rightarrow N$ gravitational transition form factors are entered to the calculations as the main input parameters. First we revisit the transitional gravitational form factors of $N(1535) \rightarrow N$, then extract the values of the form factors of the $N(1535)$ excited state. We observe that the gravitational form factors of $N(1535)$ in terms of $Q^2$ are well described by the multipole fit function. As a byproduct, we also calculate the pressure and energy density at the center of $N(1535)$ and estimate its mechanical radius.

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