arXiv subjects

Shahriyar Jafarzade

Publications and source records attributed to Shahriyar Jafarzade.

At least 19 recordsLinked to original sources

arXiv2026

Fine Structure and Decays of Hidden-Strangeness Tetraquarks in the Dynamical Diquark Model

We analyze the fine structure and ``fall-apart'' decay patterns of hidden-strangeness tetraquarks within the dynamical diquark model. Several well-established negative-parity resonances listed by the Particle Data Group (PDG) [$ϕ(2170)$, $η(2225)$, $η(2370)$] are examined as potential $q\bar q s\bar s$ tetraquark candidates using a Hamiltonian that incorporates (iso)spin-dependent, spin--orbit, and tensor interactions. We further show that the isovector resonances $ρ(2150)$ and $ρ_3(2250)$ observed by BESIII in $ψ(2S)\rightarrow K^{+}K^{-}η$ are compatible with a tetraquark assignment. Predictions for 28 states, including those with exotic quantum numbers, are also presented. Comparison of the model spectrum with the PDG's unverified ``Further States'' highlights additional promising candidates worth future experimental investigation. The predicted fall-apart decay channels are easily reconstructed by experiment and may stimulate ongoing searches for hidden-strangeness tetraquarks at GlueX and BESIII. While current data does not yet provide an unambiguous interpretation for any state in this range, the observation of the fall-apart modes, in addition to the distinct multiplet structure for tetraquark states from that of hybrids or glueballs, provides the most incisive test for discriminating state content.

hep-ph↗

arXiv2025

Diabatic Dynamical Diquark Model of Hidden-Strangeness Tetraquarks

We generalize our recent analysis of hidden-strangeness tetraquarks within the dynamical diquark model from its adiabatic form (in which each state is described solely by a diquark-antidiquark potential) to its diabatic form (which incorporates effects of di-hadron thresholds upon the states). We tabulate all relevant thresholds and compute the di-hadron content of each predicted state. Our results produce no particular hidden-strange tetraquark candidate whose structure is dominated by di-hadron structure, in contrast to the charm sector, where many exotic states are strongly associated with such thresholds: The hidden-strange states tend to remain compact and less influenced by di-hadron thresholds. Multiple states above 2~GeV with peculiar decay properties, including $ϕ(2170)$, $f_2(2340)$, and $η(2370)$, continue to serve as excellent hidden-strange tetraquark candidates.

hep-ph↗

arXiv2025

Emergence of the polydeterminant in QCD

A generalization of the determinant appears in particle physics in effective Lagrangian interaction terms that model the chiral anomaly in Quantum Chromodynamics (PRD 97 (2018) 9, 091901 PRD 109 (2024) 7, L071502), in particular in connection to mesons. This \textit{polydeterminant function}, known in the mathematical literature as a mixed discriminant, associates $N$ distinct $N\times N$ complex matrices into a complex number and reduces to the usual determinant when all matrices are taken as equal. Here, we explore the main properties of the polydeterminant applied to (quantum) fields by using a formalism and a language close to high-energy physics approaches. We discuss its use as a tool to write down novel chiral anomalous Lagrangian terms and present an explicit illustrative model for mesons. Finally, the extension of the polydeterminant as a function of tensors is shown.

math-ph↗

arXiv2025

Hidden-Strangeness Tetraquarks in the Dynamical Diquark Model

The dynamical diquark model describes multiquark exotic hadrons in terms of diquark components nucleated by heavy quarks, and successfully explains multiple features of hidden-charm and -bottom exotics. Here we apply the model to the marginally heavy case of hidden-strange states to probe whether mesons near 2 GeV with peculiar properties, such as $ϕ(2170)$, $f_2(2340)$, and X(2370), are possible tetraquark candidates. We calculate spin-multiplet average masses using potentials obtained through lattice simulations and quark models, and we also describe the detailed spectra of the expected multiplets as a diagnostic to discern the nature of future hadrons likely to be discovered in this mass region by experiments at facilities such as BESIII, JLab, and the EIC.

hep-ph↗

arXiv2025

Ordinary and exotic mesons in the extended Linear Sigma Model

The extended Linear Sigma Model (eLSM) is a hadronic model based on the global symmetries of QCD and the corresponding explicit, anomalous, and spontaneous breaking patterns. In its basic three-flavor form, its mesonic part contains the dilaton/glueball as well as the nonets of (pseudo)scalar and (axial-)vector mesons, thus chiral symmetry is linearly realized. In the chiral limit and neglecting the chiral anomaly, only one term -- within the dilaton potential -- breaks dilatation invariance. Spontaneous symmetry breaking is implemented by a generalization of the Mexican-hat potential, with explicit symmetry breaking responsible for its tilting. The overall mesonic phenomenology up to 2 GeV is in agreement with the PDG compilation of masses and decay widths. The eLSM was enlarged to include other conventional quark-antiquark nonets (pseudovector and orbitally excited vector mesons, (axial-)tensor mesons, etc.), as well as two nonets of hybrid mesons, the lightest one with exotic quantum numbers $J^{PC} = 1^{-+}$ not allowed for $\bar{q}q$ objects such as the resonance $π_1(1600)$ and the recently discovered $η_1(1855)$. In doing so, different types of chiral multiplets are introduced: heterochiral and homochiral multiplets, which differ in the way they transform under chiral transformations. Moreover, besides the scalar glueball, the tensor, the pseudoscalar and the vector glueballs were coupled to the eLSM: the scalar $f_0(1710)$ turns out to be mostly gluonic, the tensor glueball couples strongly to vector mesons, and the pseudoscalar glueball couples can be assigned to $X(2370)$ or $X(2600)$. The eLSM contains chiral partners on an equal footing and is therefore well suited for studies of chiral symmetry restoration at nonzero temperature and densities. The QCD phase diagram and the location of the critical endpoint were investigated within this framework.

hep-ph↗

arXiv2024

Scalar field with a time-independent classical source, not trivial after all: from vacuum decay to scattering

Historically it has been believed that a time-independent classical source has no effect on the scattering of relativistic uncharged field, in contrast with single particle quantum mechanics. In this work we show that the dynamics is not trivial. We solve exactly for the scattering amplitudes and find that a key ingredient is the production of particles from the unstable vacuum, conceptually similar to the Schwinger mechanism. We compute exactly the probabilities for the vacuum to decay in $n$ particles. The time dependence of such probabilities displays interesting properties such as the quantum Zeno effect and in particular has no regime where the exponential decay law is a good approximation. We show that the trivial scattering found in the past is the byproduct of the adiabatic switching of the interaction. In fact, it is not possible to switch off the interaction (adiabatically or otherwise) at distant times and recover the exact results. Finally, this non trivial vacuum behavior is a source of particle production. We argue that such non-perturbative calculations can be phenomenologically relevant for the production processes that are suppressed at the lower orders in perturbation theory, for instance dilaton production in a medium.

hep-th↗

arXiv2024

Anomalous interactions between mesons with nonzero spin and glueballs

Topologically nontrivial fluctuations control the anomalous interactions for the $η$ and and $η\prime$ pseudoscalar mesons. We consider the anomalous interactions for mesons with higher spin, the heterochiral nonets with $J^{P C} = 1^{+ -}$ and $2^{- +}$. Under the approximation of a dilute gas of instantons, the mixing angle between non-strange and strange mesons decreases strongly as $J$ increases, and oscillates in sign. Anomalous interactions also open up new, rare decay channels. For glueballs, anomalous interactions indicate that the $X(2600)$ state is primarily gluonic.

hep-ph↗

arXiv2023

Tensor meson couplings in AdS/QCD

We study the hadronic and radiative couplings of the $f_2(1270)$ meson within the hard- and soft-wall models of AdS/QCD. The results for the tensor meson-nucleon-nucleon coupling ($g_{f_2NN}$) and tensor meson-photon-vector meson coupling ($g_{f_2γρ}$) are compared to the ones obtained by using the dispersion relations and amplitude methods, respectively. Qualitative agreement with different analyses implies the reliability of the holographic description of spin-2 meson.

hep-ph↗

arXiv2023

Phenomenology of light mesons with $J = 2, 3$

In this thesis, I present the results for light mesons with $J=2,3$ within an effective hadronic model, the so-called extended Linear Sigma Model (eLSM). This model is based on the approximate chiral symmetry of QCD. Qualitative agreement between model results and PDG as well as LQCD data is obtained. Various predictions for the radiative decays can be tested in e.g., GlueX and CLAS12 experiments at Jefferson Lab. After applying the chiral model for well-established spin-2 mesons (with $J^{PC}=2^{++}$), I move on to their chiral partners (the axial-tensor mesons with $J^{PC}=2^{++}$), where the resonances are still missing. Large decay widths are predicted in the chiral model as well as in LQCD simulations.Furthermore, I describe the decays of the spin-2 tensor glueball $G_2(???)$ within the eLSM, which can be helpful in future experimental searches e.g., BESIII and LHCb experiments. Some isoscalar tensor resonances of PDG with a mass of around 2 GeV are studied, and at present, the best tensor glueball candidate turns out to be the broad resonance $f_2(1950)$. In the case of the ground-state spin-3 mesons ($J^{PC}=3^{--}$), our chiral model is limited to the $SU(3)$ flavor symmetry because of the yet unknown chiral partners ($J^{PC}=3^{++}$). The effective model results are in good agreement with the PDG data and LQCD results, and the predictions for the radiative decays can be interesting for photoproduction experiments such as GlueX and CLAS12. Additional estimates for the decay ratios of the $G_3(???)$ tensor glueball with $J^{PC}=3^{--}$ are also presented. The role of the glueball spectrum at non-zero temperature is explored within the Glueball Resonance Gas model below the critical temperature of the pure Yang-Mills sector of the QCD phase diagram. It turns out that the latest glueball spectrum from LQCD can well describe the pressure up to almost the critical temperature.

hep-ph↗

arXiv2023

Three-body decays of $π_{2}(1670)$ and $ρ_{3}(1690)$ via the Sill distribution

We present the three-body decays for the resonances $π_{2}(1670)$ and $ ρ_3(1690)$. We use an effective model based on the flavor symmetry and have assumed the Sill distribution for describing the lie-shape of intermediate unstable resonances. The vector-pseudoscalar meson decay channel is considered as an intermediate step to explain the decay of three-pseudoscalar meson channels.

hep-ph↗

arXiv2023

The role of pomeron states in the Glueball Resonance Gas

In this note, we present our recent analyses of the thermodynamic properties of the glueball resonance gas. We observe that the dominant contribution to the thermodynamic quantities, such as pressure, trace anomaly, and entropy, is coming from the free glueball gas with the states of positive charge conjugation (i.e., pomeron). A comparison of pomeron states obtained from LQCD and functional methods within the glueball resonance gas model is also presented.

hep-ph↗

arXiv2023

Is $f_2(1950)$ the tensor glueball?

Glueballs remain an experimentally undiscovered expectation of QCD. Lattice QCD (As well as other theoretical approaches) predicts a spectrum of glueballs, with the tensor ($J^{PC}=2^{++}$) glueball being the second lightest, behind the scalar glueball. Here, using a chiral hadronic model, we compute decay ratios of the tensor glueball into various meson decay channels. We find the tensor glueball to primarily decay into two vector mesons, dominated by $ρρ$ and $K^*K^*$ channels. These results are compared to experimental data of decay rates of isoscalar tensor mesons. Based on this comparison, we make statements on the eligibility of these mesons as potential tensor glueball candidates: the resonance $f_2(1950)$ turns out to be, at present, the best match as being predominantly a tensor glueball.

hep-ph↗

arXiv2022

Thermodynamics of the Glueball Resonance Gas

We study the thermodynamic properties -- pressure, entropy and trace anomaly -- of a gas of glueballs that includes the glueball states obtained by various lattice simulations. We show that this model, called Glueball Resonance Gas (GRG) approach, describes well the thermal properties of the Yang-Mills sector of QCD below the critical temperature $T_c$, provided that $T_c$ is properly matched to the corresponding determination of the glueball masses, obtaining $T_c \sim 320 \pm 20$ MeV. The inclusion into the GRG of heavier glueballs not yet seen on the lattice, assuming that glueballs follow Regge trajectories as quark-antiquark states do, leads only to a small correction. We consider the contribution to the pressure of the interactions between scalar-scalar and tensor-tensor glueballs, which turn out to be also negligible.

hep-ph↗

arXiv2022

A phenomenological note on the missing $ρ_2$ meson

The $ρ_2$ meson is the missing isovector member of the meson nonet with the quantum numbers $J^{PC}=2^{--}$. It belongs to the class of $ρ$-mesons such as the vector meson $ρ(770)$, the excited vector $ρ(1700)$ and the tensor $ρ_3(1690)$. Yet, despite the rich experimental and theoretical studies for other $ρ$-meson states, no resonance that could be assigned to the $ρ_2$ meson has been measured. In this note, we present the results for the mass and dominant decay channels of the $ρ_2$ meson within the extended Linear Sigma Model.

hep-ph↗

arXiv2022

From well-known tensor mesons to yet unknown axial-tensor mesons

While the ground-state tensor ($J^{PC}=2^{++}$) mesons $a_{2}(1320)$, $K_{2}^{\ast}(1430)$, $f_{2}(1270)$, and $f_{2}^{\prime}(1525)$ are well known experimentally and form an almost ideal nonet of quark-antiquark states, their chiral partners, the ground-states axial-tensor ($J^{PC}=2^{--}$) mesons are poorly settled: only the kaonic member $K_2(1820)$ of the nonet has been experimentally found, whereas the isovector state $ρ_2$ and two isoscalar states $ω_2$ and $ϕ_2$ are still missing. Here, we study masses, strong, and radiative decays of tensor and axial-tensor mesons within a chiral model that links them: the established tensor mesons are used to test the model and to determine its parameters, and subsequently various predictions for their chiral partners, the axial-tensor mesons, are obtained. The results are compared to current lattice QCD outcomes as well as to other theoretical approaches and show that the ground-state axial-tensor mesons are expected to be quite broad, the vector-pseudoscalar mode being the most prominent decay mode followed by the tensor-pseudoscalar one. Nonetheless, their experimental finding seems to be possible in ongoing and/or future experiments.

hep-ph↗

arXiv2021

Phenomenology of $J^{PC} = 3^{--}$ tensor mesons

We study the strong and radiative decays of the anti-quark-quark ground state $J^{PC} = 3^{--}$ ($n^{2 S + 1} L_J = 1^3 D_3$) nonet {$ρ_{3} (1690)$, $K_{3}^{\ast} (1780)$, $ϕ_{3} (1850)$, $ω_{3} (1670)$} in the framework of an effective quantum field theory approach, based on the $SU_\mathrm{V}(3)$-flavor-symmetry. The effective model is fitted to experimental data listed by the Particle Data Group. We predict numerous experimentally unknown decay widths and branching ratios. An overall agreement of theory (fit and predictions) with experimental data confirms the $\bar{q} q$ nature of the states and qualitatively validates the effective approach. Naturally, experimental clarification as well as advanced theoretical description is needed for trustworthy quantitative predictions, which is observed from some of the decay channels. Besides conventional spin-$3$ mesons, theoretical predictions for ratios of strong and radiative decays of a hypothetical glueball state $G_3 (4200)$ with $J^{PC} = 3^{--}$ are also presented.

hep-ph↗

arXiv2020

Gamma function solutions to the star-triangle equation

In the paper, we clarify some relations between solutions to the star-triangle equation via the gauge/YBE correspondence. We consider two solutions to the star-triangle relation in terms of Euler's gamma function. We derive these solutions from the reduction of certain basic and hyperbolic hypergeometric integral identities. These identities can be interpreted as equality of the supersymmetric partition functions of a specific three-dimensional N=2 supersymmetric dual theories.

math-ph↗

arXiv2018

New Pentagon Identities Revisited

We present a new solution to the pentagon identity in terms of gamma function. We obtain this solution by taking the gamma function limit from the pentagon identity related to the three-dimesional index. This limit corresponds to the identification of the sphere partition function of dual theories and being equivalent to the star-triangle relation in statistical mechanics which corresponds to the `strongly coupled' regime of the Faddeev-Volkov model.

math-ph↗