arXiv subjects

H. Nematollahi

Publications and source records attributed to H. Nematollahi.

5 recordsLinked to original sources

arXiv2026

Measure of the kaon structure: generalized valence quark distribution functions and form factors

We investigate the structure of the $K^+$ meson through calculating its valence-quark (anti quark) generalized parton distribution functions (GPDs) and form factors (FFs). For this purpose, we use a theoretical framework which is based on the exponential representation scheme (ERS). In this scheme the valence-quark GPDs of the light mesons, including the kaon, are considered as the valence quark distribution function crossed by the exponential of a profile function, at zero skewness. We apply the modified chiral quark model ($χQM$ ) to obtain the input valence distribution functions of the kaon in above scheme and calculate its valence GPDs. The kaon's electromagnetic and gravitational form factors are also determined and compared with existing experimental data and the results of some theoretical and phenomenological models.

hep-ph↗

arXiv2025

Unpolarized valence GPDs and form factors of pion in the modified chiral quark model

We calculate the valence generalized parton distribution functions (GPDs) of pion at zero skewness applying a theoretical approach in which the valence GPDs are related to valence quark distribution functions, directly. To this end, we use the results of modified chiral quark model ($χQM$) for the valence quark distributions of pion obtained in our previous work. We also determine the electromagnetic and gravitational form factors of pion and compare the results of our theoretical model for valence GPDs and form factors of pion with the results of some other models and available experimental data.

hep-ph↗

arXiv2020

Non-Extensive Behaviour of the QCD Strong Coupling Constant

The compatibility of theoretically calculated values for the strong coupling constant,through the renormalization group approach with experimental data is studied. There exist considerable divergence in-between theoretical and experimental results at low energies, which can not be explained by thermal field theory and considering chemical potential. Such great deviation can be treated successfully by considering the q-generalized statistical effects through adding a q-nonextensive parameter in the fitting of theoretical results on experimental data.

hep-ph↗

arXiv2014

Unpolarized transverse momentum dependent densities based on the modified chiral quark model

We investigate the transverse momentum dependent (TMD) quark and gluon distribution functions in the modified chiral quark model ($χQM$). Calculations of the TMD quark and gluon densities, using the modified $χQM$ are done for the first time in this article. For this propose we first formulate the TMD interactions that occur in the $χQM$ at low $Q^2$ scale ($Q^2=0.35~ GeV^2$) and then obtain the TMD parton distributions inside the proton, considering the interactions. To this end, we need to compute the TMD bare quark distributions. These TMD bare densities are calculated, using the solution of Dirac equation with a squared radial symmetry potential . It is shown that our results consist appropriate behavior which are expecting for the TMD parton distributions.

hep-ph↗

arXiv2014

New insight into $nd\rightarrow$ $^3Hγ$ process at thermal energy with pionless effective field theory

We take a new look at the neutron radiative capture by a deuteron at thermal energy with the pionless effective field theory (EFT($π\!\!\!/$)) approach. We present in detail the calculation of $nd\rightarrow$ $^3Hγ$ amplitudes for incoming doublet and quartet channels leading to the formation of a triton fully in the projection method based on the cluster-configuration space approach. In the present work, we consider all possible one-body and two-body photon interaction diagrams. In fact, additional diagrams that make significant changes in the results of the calculation of the total cross section in the $nd\rightarrow$ $^3Hγ$ process are included in this study. The properly normalized triton wave function is calculated and taken into consideration. We compare the cross section of the dominant magnetic M1-transition of $nd\rightarrow$ $^3Hγ$ up to next-to-next-to-leading order $\textrm{N}^2\textrm{LO}$ with the results of the previous model-dependent theoretical calculations and experimental data. The more acceptable results for cross section $σ^{(2)}_{tot}=0.297\;(\textrm{LO})+0.124\;(\textrm{NLO})+0.048\;(\textrm{N}^2\textrm{LO})=[0.469\pm0.033]\:\textrm{mb}$ show order by order convergence and cutoff independence. No three-body currents are needed to renormalize observables up to $\textrm{N}^2\textrm{LO}$ in this process.

nucl-th↗