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K. Azizi

Publications and source records attributed to K. Azizi.

At least 37 records · Page 2Linked to original sources
arXiv2026

Semileptonic $Ω_{b}^{*}\rightarrowΩ_{c}^{*} \ell \barν_{\ell}$ transition in QCD

We employ the QCD sum rule method to study the semileptonic weak decay of the single bottom baryon $Ω_{b}^{*}$ with spin $\frac{3}{2}$ into the single charmed baryon $Ω_{c}^{*}$ with spin $\frac{3}{2}$, corresponding to a $\frac{3}{2}\rightarrow\frac{3}{2}$ weak transition. A three-point correlation function is calculated in both the physical and theoretical sides to derive the sum rules for the form factors of the transition. The analysis incorporates both the perturbative and non-perturbative contributions up to mass dimension six. After determining the working regions of the auxiliary parameters and performing numerical calculations of the sum rules of the form factors, we extract the $q^2$-dependent fit functions for the form factors. The obtained fit functions are then applied to compute the decay widths of the $Ω_{b}^{*}\rightarrowΩ_{c}^{*} \ell \barν_{\ell}$ transition in all lepton channels. Our results may serve as useful theoretical benchmarks for future experimental investigations of the semileptonic $Ω_{b}^{*}\rightarrowΩ_{c}^{*} \ell \barν_{\ell}$ weak decays and the weak dynamics of excited heavy baryons.

hep-ph↗
arXiv2026

Double strange hybrid baryon

We investigate the spectroscopic properties of the double strange hybrid baryon with quark content $ssqg$ within the framework of QCD sum rule. Using an interpolating current with explicit gluonic degrees of freedom, the two-point correlation function is analyzed in terms of two independent Lorentz structures, $\slashed{q}$ and $I$. The operator product expansion is carried out by including vacuum condensates up to dimension ten, and the corresponding sum rules are derived for both structures. By taking the average of the results obtained from the two Lorentz structures, we extract the masses and pole residues of the ground and first excited states. For the ground state, we obtain a mass of $\widetilde{M } = (1593.44\pm 130.29)~ \mathrm{MeV}$ and a residue of $\widetilde{λ} = (2.57\pm 0.40) \times10^{-3} ~\mathrm{GeV}^5$. For the first excited state, the corresponding values are $M = (1897.47\pm 124.44)~ \mathrm{MeV}$ and $λ= (2.88\pm 0.62) \times10^{-3} ~\mathrm{GeV}^5$. The obtained results provide theoretical predictions for the double strange hybrid baryon spectrum and may be useful for future experimental searches as well as further nonperturbative studies of hybrid hadrons.

hep-ph↗
arXiv2026

Implications of exclusive photon leptoproduction measurements for the proton charge-radius puzzle

In the present study, we extend our previous analysis of the proton electromagnetic form factors (FFs) extracted from exclusive photon leptoproduction (EP) measurements in kinematic regions where the Bethe-Heitler (BH) process dominates the cross section by including all currently available high-precision EP data from the CLAS and Hall~A Collaborations. Using the same phenomenological framework, we investigate the consistency among the different data sets, determine the proton electromagnetic FFs within several fitting scenarios, and extract the corresponding charge and magnetic radii. A significant tension is observed between the CLAS 2018 measurements and the remaining EP data. We show that excluding this data set, or restricting its kinematic coverage by imposing suitable low-$|t|$ cuts, leads to stable fits with good quality and consistent FFs. For all analyses, the extracted proton charge radius is smaller than the Particle Data Group average and most determinations based on elastic electron-proton scattering. However, the results are consistent, within uncertainties, with the PRad measurement and muonic hydrogen spectroscopy. In contrast, the magnetic radius is found to be compatible with the current world average. These results demonstrate that BH-dominated EP measurements provide an independent and complementary approach to determine the electromagnetic structure of the proton and offer additional support for the small-radius solution of the proton charge-radius puzzle.

hep-ph↗
arXiv2026

Semileptonic and nonleptonic weak decays of bottom baryons $Ω^{(*)}_{b}$

We present an investigation into the semileptonic and nonleptonic weak decays of bottom baryons $Ω^{*}_{b}$ and $Ω_{b}$ within the framework of three-point QCD sum rules. In the semileptonic sector, the $Ω^{*}_b\rightarrowΩ_c\ell\barν_{\ell}$ and $Ω_b\rightarrowΩ^*_c\ell\barν_{\ell}$ transitions are specifically considered. Utilizing the operator product expansion up to dimension six, the responsible form factors of these decays are obtained. The acquired form factors enable us to determine the decay widths in three leptonic channels. Branching ratios related to the $Ω_{b}$ baryon semileptonic decays are also presented. These invariant form factors are subsequently employed as inputs to determine the nonleptonic weak decay widths in various modes with emitting a pseudoscalar or vector meson. An extensive investigation into all possible decay channels of bottom baryons provides valuable information for future experiments to examine the SM predictions, explores the new physics effects in heavy baryonic decays, and advances the understanding of the internal structure of heavy baryons.

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arXiv2026

Hybrid stars with hyperons: structure based on QCD sum rule coupling constants

We present a comprehensive study of hybrid stars composed of hadrons, leptons, and quarks within a relativistic mean-field framework. Using coupling constants derived from QCD sum rules (QCDSR), we first determine the bulk properties of nuclear matter and evaluate the single-particle potentials of nucleons and hyperons to constrain the hadronic sector. The equation of state (EOS) under beta equilibrium is then constructed employing the $σ-ω-ρ$ model for the hadronic phase, while the quark phase is described using both the MIT bag model and the Nambu-Jona-Lasinio (NJL) model. The hadron-quark phase transition is analyzed through both Gibbs and Maxwell constructions. Based on resulting EOSs, we obtain the mass-radius relations of hybrid stars, investigate particle fractions and their radial distributions, and calculate the tidal Love number ($\mathcal{K}_{2}$) and the dimensionless tidal deformability ($\varLambda$). Our results provide quantitative predictions relevant for comparison with current multimessenger astrophysical observations.

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arXiv2026

Comprehensive Mass Predictions: From Triply Heavy Baryons to Pentaquarks

In this article, we use two different methods for studying the mass spectra of fully-heavy baryons and pentaquarks. In the first section, we use state-of-the-art machine learning methods, such as deep neural networks and the Particle Transformer model architecture, to predict baryon masses directly from their quantum numbers, based on experimental information on hadrons from the Particle Data Group (PDG). We use this data-driven approach for the case of fully heavy baryons, and a large number of exotic pentaquark states, going much beyond the well-known $ P_c^+(4380) $ and $ P_c^+(4457) $ candidates. Subsequently,we extend the Gürsey-Radicati mass formula to incorporate the contributions of charm and bottom quarks, enabling analytical calculations for both ground and radially excited states of baryons and pentaquarks. The results obtained from both approaches demonstrate strong agreement with experimental data where available and make predictions for a number of unobserved states, including higher radial excitations. By addressing the question through both data-driven prediction and analytical modeling in different frameworks, this study offers complementary insights into the mass spectrum of conventional and exotic hadrons, guiding future experimental searches.

hep-ph↗
arXiv2026

Kaons in hot and dense QCD

We present a systematic QCD sum-rule analysis of the in-medium properties of the charged kaon doublet $K^{\pm}$ over the full $(T,ρ)$ plane relevant to current and forthcoming heavy-ion experiments. Working within the QCD sum-rule framework and incorporating temperature-and density-dependent quark, gluon, and mixed condensates, we derive Borel-transformed sum rules for the effective masses $m_{K^{\pm}}$, the pseudoscalar decay constants $f_{K^{\pm}}$, and the vector self-energy $Σ_{v}$ of both charged states simultaneously. Our vacuum results, $m_{K^{-}} = 494.6^{+4.9}_{-6.9}$~MeV and $f_{K^{-}} = 157.3^{+4.1}_{-2.9}$~MeV (with near-degenerate $K^{+}$ values), are in excellent agreement with Particle Data Group values at the sub-percent level. In the medium, $m_{K^{\pm}}$ decreases monotonically with increasing baryon density and temperature, signalling progressive partial restoration of chiral symmetry. A pronounced mass splitting $Δm = m_{K^{-}} - m_{K^{+}}$ develops in baryonic matter, driven by the opposite sign of the Weinberg--Tomozawa vector interaction for the two charge states; it reaches $|Δm| \sim 0.35$~GeV near $ρ\simeq 3.2\,ρ_{\rm sat}$ at $T = 0$ and is partially quenched by thermal fluctuations. A central outcome of this study is the extraction of the critical onset density $ρ_c$, defined as the threshold beyond which the in-medium modifications of $K^{-}$ properties signal the onset of the transition toward the chirally restored phase. We stress that $ρ_c(T)$ should not be interpreted as a precise determination of the QCD critical point-a task beyond the reach of any current effective framework-but rather as an indicator ....

hep-ph↗
arXiv2026

Scalar molecules $η_{b}B_{c}^{-}$ and $η_{c}B_{c}^{+} $ with asymmetric quark contents

The hadronic scalar molecules $\mathcal{M}_{b}$ and $\mathcal{M}_{c}$ with asymmetric quark contents $bb \overline{b}\overline{c}$ and $cc \overline{c} \overline{b}$ are explored by means of the QCD sum rule method. Their masses and current couplings are calculated using the two-point sum rule approach. The obtained results show that they are strong-interaction unstable particles and transform to ordinary mesons' pairs. The molecule $\mathcal{M} _{b}$ dissociates through the process $\mathcal{M}_{\mathrm{b}}\to η_{b}B_{c}^{-}$. The decays $\mathcal{M}_{\mathrm{c}}\rightarrow η_{c}B_{c}^{+}$ and $J/ψB_{c}^{\ast +}$ are dominant modes for the molecule $\mathcal{M}_{c}$. The full decay widths of the molecules $\mathcal{ \ \ M}_{b}$ and $\mathcal{M}_{c}$ are estimated using these decay channels, as well as ones generated by the annihilation of $b\overline{b}$ and $c \overline{c}$ quarks in $\mathcal{M}_{b}$ and $\mathcal{M}_{c}$, respectively. The QCD three-point sum rule method is employed to find partial widths all of these channels. This approach is required to evaluate the strong couplings at the molecule-meson-meson vertices under consideration. The mass $m=(15728 \pm 90)~\mathrm{MeV}$ and width $Γ[ \mathcal{M}_b] =(93 \pm 17)~ \mathrm{MeV}$ of the molecule $\mathcal{M}_{b}$ , and $\widetilde{m}=(9712 \pm 72)~\mathrm{MeV}$ and $Γ[\mathcal{M}_c] =(70 \pm 10)~ \mathrm{MeV}$ in the case of $\mathcal{M}_{c} $ offer valuable guidance for experimental searches at existing facilities.

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arXiv2026

Tensor form factors of decuplet hyperons in QCD

Tensor form factors encode essential information about the internal spin structure and tensor dynamics of baryons. In this work, we investigate the tensor form factors of the baryon hyperons $Ω^-$, $Σ^{*+}$, and $Ξ^{*-}$ within the framework of QCD sum rules. The complete set of tensor form factors is numerically evaluated in the momentum transfer region $0<Q^2<10~\text{GeV}^2$. In addition, the quark tensor charges of the considered hyperons are extracted in the forward limit. The results provide new non-perturbative insight into the tensor structure and spin content of spin-$3/2$ baryons and offer valuable theoretical input for future phenomenological analyses and experimental studies.

hep-ph↗
arXiv2026

Molecular states $J/ψB_{c}^{+}$ and $η_{c}B_{c}^{\ast +} $

Hadronic molecules $\mathfrak{M}=J/ψB_{c}^{+}$ and $\widetilde{\mathfrak{ \ M}}=η_{c}B_{c}^{\ast +}$ are investigated in the framework of QCD sum rule method. These particles with spin-parities $J^{\mathrm{P}}=1^+$ have the quark contents $cc \overline{c}\overline{b}$. We compute their masses and current couplings and find that they are numerically very close to each other coinciding within accuracy of the sum rule method. Therefore, we concentrate on the molecule $J/ψB_{c}^{+}$ and explore features of this state in a detailed form. Our prediction $m=(9740 \pm 70)~\mathrm{MeV}$ for its mass means that $\mathfrak{M}$ easily decays to pairs of ordinary mesons through strong interactions. There are two mechanisms responsible for transformations of $\mathfrak{M}$ to conventional mesons. The fall-apart mechanism generates the dominant decay channels $\mathfrak{M} \to J/ψB_{c}^{+}$ and $\mathfrak{M} \to η_{c}B_{c}^{\ast +}$. Annihilation of $ \overline{c}c$ quarks triggers subdominant processes with various final-state $B$ and $D$ mesons: Six of such channels are considered in this work. The partial widths all of decays are computed using the three-point sum rule approach. The width $Γ[ \mathfrak{M}]=(121 \pm 17)~ \mathrm{MeV }$ of the hadronic axial-vector molecule $\mathfrak{M}$, as well as its mass provide valuable information for running and future experiments.

hep-ph↗
arXiv2026

Masses of Purely Top-Quark Bound States: Toponium and the Triply-Top Baryon

We investigate the pseudoscalar ($η_t$) and vector ($ψ_t$) toponium states, as well as the triply-top baryon ($Ω_{ttt}$), using the QCD sum-rule method. This study was motivated by the recent observation of a pseudoscalar enhancement near the $t\bar{t}$ threshold, reported by the CMS and ATLAS collaborations with a statistical significance exceeding $5σ$. In the calculations, we consider both the perturbative and nonperturbative contributions, with the nonperturbative operators taken into account up to dimension eight. The results obtained for the pseudoscalar toponium provide a theoretical estimate that is consistent with the near-threshold events observed in recent experimental studies. The calculated negative binding energy for both the pseudoscalar and vector toponium states reflects the strong correlation within the $t\bar{t}$ system and can be interpreted as $t\bar{t}$ bound states, while the calculated central mass for the $Ω_{ttt}$ slightly exceeds the central value of the sum of the constituent top-quark masses. The results of this study can provide a precise theoretical guide for future experimental investigations of these states, which are composed entirely of top quarks, at high-energy colliders such as the LHC and future facilities like the FCC.

hep-ph↗
arXiv2026

Analysis of Fully Heavy $P_{(3c2b)}$ and $P_{(3b2c)}$ Pentaquark Candidates

Recent progress in experimental facilities, together with larger data samples and more refined analysis strategies has enabled the observation of many exotic hadronic states, adding new members to the hadron spectrum. Each newly reported signal encourages further experimental searches and simultaneously motivates theoretical studies aimed at uncovering additional nonconventional states. Motivated by this perspective and by the increasing interest in systems containing multiple heavy quarks, we present a spectroscopic study of fully heavy pentaquark candidates with spin-parity quantum numbers $J^{P}=\frac{1}{2}^{-}$ and quark contents $QQQ'Q\bar{Q'}$, $QQQ'Q'\bar{Q}$, and $Q'Q'QQ\bar{Q}$, where $Q(Q')$ represents either $c(b)$ or $b(c)$ quarks. We employ the QCD sum rule approach with three different types of interpolating currents to obtain the corresponding masses and current coupling constants of the considered states. The following masses for the states containing three $c$ and two $b$ quarks are predicted: $m_{(3c2b)}=14479.30\pm75.06~\mathrm{MeV}$ using the current $J_1$, $\tilde{m}_{(3c2b)}=14276.80\pm76.29~\mathrm{MeV}$ using $J_2$, and $\bar{m}_{(3c2b)}=14276.80\pm76.29~\mathrm{MeV}$ using $J_3$. The corresponding predictions for the states containing three $b$ and two $c$ quarks are as $m_{(3b2c)}=17458.90\pm130.11~\mathrm{MeV}$ with $J_1$, $\tilde{m}_{(3b2c)}=17202.70\pm132.37~\mathrm{MeV}$ with $J_2$, and $\bar{m}_{(3b2c)}=17250.80\pm131.98~\mathrm{MeV}$ with $J_3$, respectively. In addition, we provide the corresponding current coupling constants, which can serve as useful inputs for analyses of decay properties and interaction mechanisms of these fully heavy pentaquark candidates.

hep-ph↗
arXiv2026

Doubly heavy spin-$\frac {3}{2} $ baryons spectrum in the ground and excited states

This study employs QCD sum rules to predict the masses and residues of spin-$\frac {3}{2} $ doubly heavy baryons including two heavy quarks (c and/or b) and one light quark, specifically focusing on $ Ξ_{cc}^*$, $ Ξ_{bc}^*$, $ Ξ_{bb}^*$, $ Ω_{cc}^*$, $ Ω_{bc}^*$ and $ Ω_{bb}^*$. Our study provides results for the ground state ($1S$), first orbital excitation ($1P$), and the first radial excitation ($2S$), within a consistent theoretical framework. In addition to mass spectra, we provide residue calculations as well. The calculated residues are essential for estimating the decay widths and branching ratios of these baryons at different decay channels. Our analysis incorporates nonperturbative QCD effects through operators up to dimension ten, leading to improved precision in the mass and residue calculations. These predictions offer crucial guidance for ongoing and future experimental searches, particularly in light of the current lack of empirical data for the ground and excited states, and provide a basis for comparison with future experimental data.

hep-ph↗
arXiv2026

Determination of proton electromagnetic form factors from DVCS measurements

We present a detailed analysis of the proton electromagnetic form factors (FFs) using exclusive photon leptoproduction (EP) data in kinematic regions where the Beth-Heitler (BH) contribution dominates the deeply virtual Compton scattering (DVCS) cross section By exploiting the sensitivity of the BH amplitude to the Dirac and Pauli FFs, we extract $F_{1}(t)$, $F_{2}(t)$, and the corresponding Sachs FFs within several fitting scenarios based on dipole and $P$-pole parametrizations, and evaluate the charge and magnetic radii of the proton. In this fitting scenario, we show that EP measurements in the range $0.11 < |t| < 0.45~\mathrm{GeV}^2$ can provide constraints on $F_1(t)$, while offering limited sensitivity to $F_2(t)$. The extracted charge radius values tend to be smaller than those obtained from traditional elastic electron-proton scattering measurements and are consistent, within uncertainties, with recent hig-precision PRad results. These findings indicate that EP measurements, especially when covering smaller values of $|t|$, can serve as a complementary tool for determining the proton electromagnetic structure and may contribute to ongoing efforts to better understand the proton charge radius.The methodology developed here provides a framework for future combined analyses of EP and elastic electron-proton scattering data which enables a unified determination of the nucleon FFs.

hep-ph↗
arXiv2026

Light double-gluon hybrid states

We investigate light hybrid mesons composed of a light quark-antiquark pair and two gluons within the framework of QCD sum rules. We focus on states with quantum numbers $J^{\mathrm{PC}} = 0^{++}, 0^{+-}, 0^{-+}, 0^{--}$ and $J^{\mathrm{PC}} = 1^{++}, 1^{+-}, 1^{-+}, 1^{--}$. By employing various interpolating currents constructed from valence light quarks and gluon fields, we determine the masses and current couplings of the $\bar{q}GGq$, $\bar{q}GGs$, and $\bar{s}GGs$ hybrid configurations. Nonperturbative effects are incorporated through quark and gluon condensates up to dimension twelve in the operator product expansion, improving the reliability of the numerical predictions. The results presented here may provide useful input for future experimental searches for light hybrid mesons and can also serve as a basis for studies of their decay properties and interactions with other hadronic states.

hep-ph↗
arXiv2026

Two-body nonleptonic decays of $Ω_{b}\rightarrow Ω_{c}$ beyond tree level

We study the nonleptonic decays of $Ω_{b}\rightarrowΩ_{c} P (V)$ with eight pseudoscalar and vector mesons using the naive factorization approach. We analyze all relevant topologies (the tree-level, color-suppressed, and penguin) of these decays and calculate the decay amplitude for each separately. We determine the decay rates, branching ratios and compare our results with those from other theoretical predictions. The results obtained may be useful for the analysis of the related data in both ongoing and future experiments.

hep-ph↗
arXiv2026

Axial-vector molecules $ΥB_{c}^{-}$ and $η_{b}B_{c}^{\ast-} $

Axial-vector hadronic molecules $\mathcal{M}_{\mathrm{AV}}=ΥB_{c}^{-} $ and $\widetilde{\mathcal{M}}_{\mathrm{AV}}=η_{b}B_{c}^{\ast -} $ with the quark content $bb \overline{b}\overline{c}$ are studied using QCD sum rule method. The spectroscopic parameters of these molecules are computed in the context of the two-point sum rule method. Predictions for their masses are identical to each other and confirm that they are structures unstable against dissociations to ordinary heavy mesons. We evaluate the width of the state $\mathcal{M}_{\mathrm{AV}}$ and assume that it is equal to that of $\widetilde{\mathcal{M}}_{\mathrm{AV}} $. To this end, we explore its dominant decay channels $\mathcal{M}_{\mathrm{AV}} \to ΥB_{c}^{-} $ and $\mathcal{M}_{\mathrm{AV}} \to η_{b}B_{c}^{\ast -}$. There also are subleading modes of $\mathcal{M}_{\mathrm{AV}}$ generated due to annihilation of $\overline{b}b$ quarks. We consider decays of the molecule $\mathcal{M}_{\mathrm{AV}}$ to pairs of the mesons $B^{\ast -} \overline{D}^{0}$, $\overline{B}^{\ast 0} D^{-}$, $B^{-} \overline{D} ^{\ast 0}$, $\overline{B}^{0} D^{\ast -}$, $\overline{B}_{s}^{\ast 0} D_{s}^{-}$, and $\overline{B}_{s}^{0} D_{s}^{\ast -}$. To find strong couplings at the $\mathcal{M}_{\mathrm{AV}}$-meson-meson vertices which determine the partial widths of these processes, we apply QCD three-point sum rule approach. The mass $m=(15800 \pm 90)~\mathrm{MeV}$ and width $ Γ[\mathcal{M}_{\mathrm{AV}}]=(114 \pm 17)~ \mathrm{MeV}$ of the molecule $\mathcal{M}_{\mathrm{AV}}$ are useful for experimental studies of fully heavy molecular structures at ongoing and planning experiments.

hep-ph↗
arXiv2026

Tensor form factors of the $Δ^+$ baryon induced by isovector and isoscalar currents in QCD

The tensor form factors of the $Δ^+$ baryon are defined through the matrix element of the tensor current and describe its internal structure and spin distribution. We present the full Lorentz decomposition for the $Δ^+ \rightarrow Δ^+$ tensor current matrix element, including all independent structures consistent with Lorentz covariance, the Rarita-Schwinger constraints, and the discrete symmetries of Hermiticity, time-reversal, and parity invariance. By investigating the tensor form factors corresponding to both the isovector and isoscalar tensor currents, we observe differences that reflect the distinct contributions of up and down quark components in the $Δ^+$ baryon.

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