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Harleen Dahiya

Publications and source records attributed to Harleen Dahiya.

At least 19 recordsLinked to original sources

In-medium properties of $D$ and $D^*$ mesons in magnetized isospin asymmetric nuclear matter

We investigate the impact of an external magnetic field on the in-medium properties of pseudoscalar ($D^0,D^+,D_s$) and vector ($D^{0*},D^{+*},D_{s}^{*}$) mesons in isospin asymmetric nuclear matter at finite temperature using a hybrid theoretical framework combining the chiral SU(3) quark mean-field (CQMF) model and the light-front quark model (LFQM). The medium-modified constituent quark masses, obtained from the CQMF model by including the magnetized Dirac sea contribution and anomalous magnetic moments of nucleons, are used as input to the LFQM calculations of meson masses, weak decay constants, and leading-twist distribution amplitudes. We further incorporate the Landau quantization of the charged mesons restricted to the lowest Landau level, while magnetic field induced pseudoscalar-vector mixing is taken into account for each $D$-$D^{*}$ doublet. We find that the external magnetic field enhances the effective masses and decay constants of both pseudoscalar and vector $D$ mesons by magnetic catalysis, while increasing baryon density generally induces an attractive mass shift and suppresses the decay constant and distribution amplitudes. The Landau level contribution further enhances the effective masses of the charged mesons, whereas the pseudoscalar-vector mixing produces a level repulsion, shifting the vector meson masses upward and the pseudoscalar meson masses downward. The interplay between magnetic field and density effects gives rise to a nontrivial medium behavior of heavy-light meson properties, with isospin asymmetry further inducing a small but systematic mass splitting across all the meson states considered. These results provide useful insights into heavy-flavor dynamics in strongly interacting matter and are relevant to ongoing and future studies at FAIR, NICA, and J-PARC.

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Leading-twist to higher-twist generalized parton distributions of the pseudoscalar mesons at non-zero skewness

We investigate the multidimensional partonic structure of spin-0 mesons, specifically the pion and the kaon, by evaluating their complete set of eight generalized parton distributions (GPDs) up to twist-4. Utilizing the light-front quark model (LFQM) with the Brodsky-Huang-Lepage (BHL) prescription, we compute these distributions in the kinematically rich non-zero skewness ($ξ\neq 0$) domain, strictly within the DGLAP region, $x \in [ξ, 1]$. To construct a three-dimensional tomographic picture, we perform Fourier transforms of the momentum-space GPDs to obtain the impact parameter dependent parton distribution functions (IPDPDFs) in the transverse plane and the corresponding diffraction patterns in the longitudinal coordinate space. The numerical results explicitly reveal the consequences of $\mathrm{SU}(3)$ flavor symmetry breaking, as the strange quark in the kaon dynamically shifts spatial localizations compared to the lighter up quarks. We also observe that while higher-twist correlations exhibit massive amplitude scaling in the pion, they are heavily suppressed by the larger macroscopic mass of the kaon.

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Magnetic moments of decuplet baryons in isospin asymmetric magnetized strange matter

We investigate the in-medium masses and magnetic moments of decuplet baryons $(Δ,Σ^*,Ξ^*,Ω^-)$ in isospin asymmetric magnetized strange matter at finite temperature within a unified chiral effective framework. Medium modifications of baryons are implemented using the chiral SU(3) quark mean-field (CQMF) model, where constituent quarks interact via scalar ($σ$, $ζ$, $δ$) and vector ($ω$, $ρ$, $ϕ$) meson fields considering the Dirac sea effects. The external magnetic field is incorporated through Landau quantization of charged particles together with anomalous magnetic moments (AMM) of baryons. The resulting in-medium mass of constituent quarks and decuplet baryons obtained from the CQMF model are subsequently employed as input to the chiral constituent quark model ($χ$CQM) to evaluate magnetic moments of baryons. Contributions from valence quarks, sea quark spin polarizations, and orbital angular momentum of the quark sea are taken into account. Our results provide a systematic understanding of how dense, hot, and magnetized environments influence the magnetic properties of decuplet baryons.

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Magnetic Moment of Octet Baryons in Isospin Asymmetric Magnetized Strange Matter

We investigate the magnetic moments of octet baryons in isospin asymmetric strange hadronic matter under strong external magnetic fields within a unified theoretical framework by combining the chiral SU(3) quark mean field (CQMF) model with the chiral constituent quark ($χ$CQM) model. At finite temperature, the inclusion of Dirac sea (DS) effect leads to magnetic catalysis attributing to the enhancement of scalar condensates with increasing magnetic field strength. As a consequence, the effective masses of the octet baryons exhibit a monotonic increase as a function of magnetic field. The results highlight the crucial role of vacuum polarization effects in determining the electromagnetic properties of baryons in strongly magnetized matter having relevance in heavy-ion collision and compact stars.

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Role of higher twist distributions in the tomography of proton

We have studied the higher-twist distributions of the proton, including T-even and T-odd transverse momentum-dependent parton distributions (TMDs). Under the umbrella of the light-front framework, we have chosen two distinctive approaches of quark-spectator systems for comparison, one inspired by the soft-wall AdS/QCD and another with a dipolar form factor at the nucleon-quark-diquark vertex. The comprehensive picture at higher-twist provided by both T-even and T-odd TMDs not only aids deeper insights into the internal structure of the proton in the quark sector but also provides an interpretation of different components of the energy-momentum tensor in quantum chromodynamics. Hence, using these standard parton distribution functions, further predictions regarding the physical insights of gravitational TMDs in momentum space are also provided.

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Space-like Sachs electric and magnetic form factors of the baryons in the asymmetric nuclear medium

In the present work, we have studied the space-like baryon Sachs form factors in the isospin asymmetric nuclear medium using the vector meson dominance (VMD) model. The in-medium effects are incorporated through the medium-modified masses of vector mesons which are calculated using the QCD sum rule approach taking density dependent scalar quark and gluon condensates as inputs from chiral SU(3) quark mean field (CQMF) model. The effective magnetic moments of the baryons are also calculated in the CQMF model. In the framework of VMD model, the photon couples to the nucleons through intermediary vector mesons with the same quantum number as that of a photon. This coupling leads to the relation of isoscalar and isovector Dirac and Pauli form factors which are then used to calculate the Sachs electric and magnetic form factors, which provide physically measurable quantities that represent the electric and magnetic distributions of the baryons. The present work aims to study the effects of asymmetric nuclear matter at finite temperature on the Sachs form factors of baryons in the space-like region. The electric and magnetic charge radii have also been calculated for the baryons in free space and dense asymmetric nuclear matter. The results obtained have been compared with other available phenomenological models, lattice simulations, and experimental data.

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Moderate-to-Large-$x$ Gluon Helicity from $J/ψ$ Production at $\sqrt{s}=27~\mathrm{GeV}$

We present a feasibility study of the longitudinal double-spin asymmetry $A_{LL}$ in inclusive $J/ψ$ production in polarized proton-proton collisions at $\sqrt{s}\approx 27~\mathrm{GeV}$ at the Spin Physics Detector (SPD) of the Nuclotron-based Ion Collider fAcility (NICA). At these moderate energies, $J/ψ$ production is dominated by gluon-gluon fusion, probing gluon momentum fractions $x\approx 0.1$-$0.2$ at central rapidity and highly asymmetric configurations at forward rapidity, where one parton can reach $x\approx 0.5$-$0.9$. This provides direct sensitivity to the poorly constrained moderate- to large-$x$ region of the gluon helicity distribution $Δg(x)$. We estimate $A_{LL}$ as a function of transverse momentum and rapidity using polarized parton distribution functions, focusing on the underlying partonic spin asymmetry. Nonperturbative long-distance effects are treated in a simplified manner and largely cancel in the asymmetry, enabling a direct assessment of gluon polarization sensitivity. We find asymmetries reaching $|A_{LL}|\approx 0.09$ at $p_T=3~\mathrm{GeV}$, with enhanced sensitivity at forward rapidity. The dominant theoretical uncertainty arises from polarized parton distribution functions. These results demonstrate that inclusive $J/ψ$ measurements at SPD/NICA provide a sensitive and complementary probe of gluon polarization at moderate and large $x$, extending constraints from RHIC into a kinematic regime not directly accessible to the EIC.

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Valence quark distribution of the pion inside a medium with finite baryon density: A Nambu--Jona-Lasinio model approach

We calculate the in-medium valence quark distribution of the pion immersed in a finite baryon density using the light-cone quark model. The medium-modified pion properties are obtained by using the constituent quark mass-dependent light cone wave functions. To obtain the constituent quark masses at finite baryon density, we employ the two-flavor Nambu--Jona-Lasinio model. We primarily focus on the in-medium electromagnetic form factor, distribution amplitude, and the parton distribution function of the pion. The parton distribution functions are also evolved from the model scale to a perturbative scale using next to leading order Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations. Furthermore, our calculated form factors are compared with available experimental measurements and lattice quantum chromodynamics studies. We also examine the Mellin moments derived from our parton distribution functions in comparison with existing extractions and theoretical model predictions.

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Mechanical properties of proton in the momentum space

We study the parametrization of the energy-momentum tensor for the case of a proton in momentum space in terms of gravitational transverse momentum-dependent distributions (TMDs). These gravitational TMDs are investigated with the inclusion of higher-twist contributions to predict the mechanical properties, specifically the transverse pressure and shear force distributions, along with the polarization-dependent $Π^q_S$ and $Π^q_A$ terms. The corresponding distributions are computed individually for both $u$ and $d$ quark flavors. The calculations have been performed in the light-cone framework using the spectator diquark model. A strong binding contribution to the transverse pressure is observed in the low-momentum space for both quark flavors of the proton.

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Extraction of Pion Unpolarized Quark Generalized Parton Distribution from Charge Form Factors

Based on a global fit to experimental measurements of the pion electromagnetic form factor and parton distribution functions (PDFs), we report a data-driven determination of the unpolarized quark generalized parton distributions (GPDs) for the case of pion in the zero-skewness limit ($ξ= 0$). The form factor is parameterized using a flexible functional form constrained by data and embedded into a GPD framework constructed from collinear PDFs and a profile function encoding transverse dynamics. This approach provides a unified description of the pion's electromagnetic structure and its spatial parton distributions. We present the extracted pion GPDs and their impact-parameter-space interpretations, offering new insights into the internal structure of the lightest QCD bound state and providing essential input for future electron-ion collider studies via the Sullivan process, as well as for the exclusive $π^+$ electroproduction at the 12~GeV Jefferson Lab program, pion-induced exclusive measurements at COMPASS, proposed pion-beam experiments at AMBER, and phenomenological and lattice investigations of the structure of the meson.

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Internal structure of light mesons using the power law wave function

In this paper, we study the internal structure of light pseudoscalar mesons using spin improved power-law wave functions. We choose the pion and the kaon for our work. We use the standard quark-quark correlation functions to calculate the distribution amplitudes (DAs), parton distribution functions (PDFs), transverse momentum dependent parton distribution functions (TMDs), and generalized parton distribution functions (GPDs) at zero skewness and form factors. We present all the above distribution functions through the overlap of light-front wave functions (LFWFs). We use leading-order Efremov-Radyushkin-Brodsky-Lepage (ERBL) equations for DAs and next-to-leading-order (NLO) Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations for PDFs to evolve them to higher scales. We find that only 41\% of the longitudinal momentum fraction is carried by the quark and antiquark of both pion and kaon at 16~GeV$^2$. The vector form factors for both the pion and the kaon are found to be in good agreement with experimental data. Similarly, the electromagnetic charge radii are found to be 0.668~fm and 0.704~fm for the pion and kaon, respectively.

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Pion Parton Distribution Functions in the Light-Cone Quark Model and Experimental Constraints

In this work, we investigate the valence quark parton distribution functions (PDFs) of the pion within the light-cone quark model. The initial quark PDFs are calculated by solving the quark-quark correlation function for the pseudoscalar mesons. The initial quark PDFs have been evolved to higher energy scales through the Dokshitzer,Gribov,Lipatov,Altarelli,Parisi (DGLAP) evolution equations. We also find that our calculated evolved PDFs match experimental and available theoretical extraction data. For the first time, we have also predicted the $F_2$ structure function at next-to-leading (NLO) order accuracy. The calculated $F_2$ structure function has been compared with the available ZEUS and H1 experimental data at DESY-HERA over a wide range of energy scales. Additionally, we display the forward pion production cross-section for the Drell-Yan process caused by pions using the pion PDFs that were calculated and the target nucleon PDFs from the LHAPDF nucleus datasets. The evolved $F_2$ structure function of the pion have been studied at the upcoming electron-ion collider energy kinematics. Overall, it was observed that the quark PDFs of pions computed using the light-cone quark model consistent with the experimental results.

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Magnetic moments of decuplet baryons in asymmetric magnetized nuclear matter

Understanding the novel QCD phenomenon under high external magnetic fields of hot and dense medium help us to develop a better understanding of the underlying quark dynamics of baryons. Using a hybrid approach based on the effective field theory that treats quarks as the fundamental degrees of freedom and calculating the individual contribution of valence, sea and orbital angular moment of sea quark, the magnetic moment of a given baryon of the decuplet family is calculated. The incorporation of Landau quantization in the vector and scalar densities of baryons help us to obtain the impact of external magnetic field on the properties of baryons within the chiral SU(3) quark mean field model (CQMF). In the present study, effective masses of the baryons are calculated using CQMF while the framework of chiral constituent quark model ($χ$CQM), extended to SU(4) sector, is used to obtain the effective magnetic moments of decuplet baryons under the influence of magnetic field.

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Chiral-odd generalized parton distributions of spin-1/2 baryons

We present the tomographical structure of baryons by studying the nonforward matrix elements of lightlike correlation functions of the tensor current. At the leading twist, with the tensor current, four chiral-odd distributions are in count. We calculate these distributions in a diquark spectator model with light-front formalism by considering purely transverse momentum transfer, i.e., zero skewness. Predictions for the nucleons and light hyperons are studied, emphasizing the difference arising from their different quark flavors.

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Gravitational form factors of baryons in a spectator diquark model

Energy momentum tensor (EMT) expresses the interaction between the gravitation and the matter fields, in which the scattering off the graviton is a natural but infeasible probe. However, the EMT can be accessed indirectly through electromagnetic interactions in quantum chromodynamics. The matrix elements of the local EMT operator are parameterized by gravitational form factors, which are subsequently related to the generalized parton distributions. Within the diquark spectator model, we investigate the gravitational form factors of baryons. We consider all the feasible pairs of quark-diquark systems to understand the behavior of each constituent quark flavor of strange and non-strange baryons.

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Spectroscopy of $ρ$-meson in symmetric nuclear medium

In this work, we investigate the behavior of the light vector \(ρ\) meson in the presence of a symmetric nuclear medium at zero temperature. We calculate the mass and decay constant of the $ρ$-meson as well as the leading twist distribution amplitudes (DAs) in the light-front quark model in vacuum, which are further investigated at different baryonic densities. We also predict the Mellin moments of the DAs and decay width of the $ρ^0 \to e^+ e^-$ process in both vacuum and medium. The evolution of DAs is carried out by the leading order (LO) Efremov-Radyushkin-Brodsky-Lepage method and compared with available predictions. For better understanding of medium effects on $ρ$-meson, we have also predicted the in-medium charge ($G_C(Q^2)$), magnetic ($G_M(Q^2)$), and quadrupole ($G_Q(Q^2)$) form factors. The in-medium charge radii, magnetic moment, and quadrupole moment have also been predicted in this work. We have found that the nuclear medium induces appreciable modifications on the mass, weak decay constant, decay width, and distribution amplitudes of the \(ρ\) meson. However, the charge radii, magnetic moment, and quadrupole moment are observed to exhibit weaker sensitivity to changes in baryonic density.

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Distribution Functions of Radially Excited Pion using the Light-Front Quark Model

We investigate the internal structure of the ground ($1S$) and the first two radially excited ($2S,3S$) states of the pion within the light-front quark model. The valence Fock sector is described using pure harmonic-oscillator eigenstates and mixed states formed as orthogonal linear combinations of these eigenfunctions. The optimal wavefunction parameters are determined through a variational procedure based on a QCD-motivated effective Hamiltonian. Using the resulting light-front wavefunctions, we study the pion distribution amplitude, parton distribution function, and electromagnetic form factor. After QCD evolution, the ground state distribution amplitude and parton distribution function are found to be in good agreement with available experimental data. At the model scale, the parton distribution functions of the $1S$ and $2S$ states show clear sensitivity to state mixing, while the distribution amplitudes and electromagnetic form factors are weakly sensitive. In contrast, for the $3S$ state, all three observables exhibit a pronounced sensitivity to mixing. The decay constants of the mixed states are also found to decrease sequentially with increasing radial excitation.

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Valence quark distribution of rho meson using light-front quark model

We investigate the partonic structure of the $ρ$ meson, the lightest spin-$1$ vector meson, within the light-front quark model (LFQM). To explore the sensitivity to model assumptions, we employ two distinct types of spin wave functions in the LFQM. Using light-front helicity wave functions, we derive explicit expressions for the leading-twist and subleading-twist quark parton distribution functions (PDFs), and evolve the leading-twist PDFs to higher scales with next-to-leading order (NLO) Dokshitzer--Gribov--Lipatov--Altarelli--Parisi (DGLAP) evolution. We have also calculated the Mellin moment from the evolved PDFs using a simple neural network frame and compared with available theoretical predictions. Furthermore, we compute the full set of nine leading-twist transverse-momentum-dependent distributions (TMDs) for the valence quark in the $ρ$ meson, including three tensor TMDs that arise from spin-$1$ tensor polarization of the hadron. Positivity constraints for the PDFs and TMDs are examined within this framework. Our findings highlight the crucial role of tensor polarization in shaping the three-dimensional partonic structure of vector mesons.

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