arXiv subjects

Harleen Dahiya

Publications and source records attributed to Harleen Dahiya.

At least 91 records · Page 5Linked to original sources

arXiv2018

Octet Baryon Masses and Magnetic Moments in Hot and Dense Isospin Asymmetric Nuclear Matter

Medium modification of the magnetic moments of octet baryons in the isospin asymmetric nuclear medium at finite temperature has been calculated using medium modified quark and baryon masses derived in chiral SU(3) quark mean field model. The magnetic moments of baryons are found to vary significantly as a function of density of nuclear medium as well as with the increase in isospin asymmetry of the medium. The rise of temperature is found to decrease the effect of isospin asymmetry on masses and magnetic moments of baryons. The results of present investigation may be helpful to understand the experimentally observed values of octet baryon magnetic moments at different experimental facilities.

nucl-th↗

arXiv2018

In-medium masses and magnetic moments of decuplet baryons

The magnetic moments of baryon decuplet are studied in vacuum as well as in the symmetric nuclear matter at finite temperature using a chiral SU(3) quark mean field model approach. The contributions coming from the valence quarks, quark sea and the orbital angular momentum of the quark sea have been considered to calculate magnetic moment of decuplet baryons. The decuplet baryon masses decrease, whereas, the magnetic moments increase significantly with the rise of baryonic density of the symmetric nuclear medium. This is because of the reason that constituent quark magnetic moment and the quark spin polarizations show considerable variation in the nuclear medium especially in the low temperature and baryonic density regime. The increase is however quantitatively less as compared to the case of octet baryon members.

hep-ph↗

arXiv2018

Wigner distributions and GTMDs in a proton using light-front quark-diquark model

We investigate the Wigner distributions and generalized transverse momentum-dependent distributions (GTMDs) for $u$ and $d$ quarks in the proton by using light-front quark-diquark model. We consider the contribution of scalar and axial-vector diquark having spin-0 and spin-1 respectively. We take different polarization configurations of quark and proton to calculate the Wigner distributions. The Wigner distributions are studied in the impact-parameter space, momentum space and mixed space for $u$ and $d$ quarks in the proton. We also study the relation of GTMDs with longitudinal momentum fraction carried by the active quark $x$ for different values of $ζ$ (skewness) which is defined as the longitudinal momentum transferred to the proton. Further, we study the GTMDs in the relation with $x$ for zero skewness $(ζ=0)$ at different values of quark transverse momentum $\textbf{p}_\perp$ as well as at different values of total momentum transferred to the proton ${\bf Δ}_\perp$.

hep-ph↗

arXiv2018

Generalized Parton Distributions of Pion for Non-Zero Skewness in AdS/QCD

We study the generalized parton distributions (GPDs) of pion for non-zero skewness by considering the leading $| q \bar{q} \rangle$ Fock state component. Inspired from AdS/QCD light-front wave functions, we calculate the pion GPDs. By taking the Fourier transforms we obtain the results for impact-parameter dependent parton distribution functions (ipdpdf) and for GPDs in longitudinal boost-invariant space. We also calculate the charge density and gravitational form factor of the pion. The pion unpolarized transverse momentum distribution (TMD) have also been calculated. The results provide rich information on the internal structure of pion.

hep-ph↗

arXiv2018

Transition magnetic moments of $J^P=\frac{3}{2}^+$ decuplet to $J^P=\frac{1}{2}^+$ octet baryons in the chiral constituent quark model

In light of the developments of the chiral constituent quark model ($χ$CQM) in studying low energy hadronic matrix elements of the ground-state baryons, we have extended this model to investigate their transition properties. The magnetic moments of transitions from the $J^P=\frac{3}{2}^+$ decuplet to $J^P=\frac{1}{2}^+$ octet baryons have been calculated with explicit valence quark spin, sea quark spin and sea quark orbital angular momentum contributions. Since the experimental data is available for only a few transitions, we have compared our results with the results of other available models. The implications of other complicated effects such as chiral symmetry breaking and SU(3) symmetry breaking arising due to confinement of quarks have also been discussed.

hep-ph↗

arXiv2018

Study of Twist-2 GTMDs in scalar-diquark model

We investigate the Generalized Transverse Momentum-dependent Distributions (GTMDs) describing the parton structure of proton using the light-front scalar-diquark model. In particular, we study the Wigner distributions for unpolarized quark in unpolarized, longitudinally-polarized and transversely-polarized proton. We also investigate the twist-2 GTMDs for unpolarized quark $(Γ=γ^+)$ in scalar-diquark model.

hep-ph↗

arXiv2018

Decay constants of pseudoscalar and vector $B$ and $D$ mesons in the light-cone quark model

We have studied the decay constants of the pseudoscalar and the vector $B$ and $D$ mesons in the framework of the light-cone quark model. We have applied a variational method to the relativistic Hamiltonian with the Gaussian-type trial wave function to obtain the values of the scale parameter $β$ in different potential models. Furthermore, using the known values of the constituent quark masses of $u$, $d$, $s$, $c$ and $b$ quarks, we have obtained the numerical results for the decay constants. We have also compared our results with the other theoretical calculations and the existing experimental results. The present work predictions have many phenomenological applications in the domain of $CP$ violation and also in the determination of the CKM matrix elements.

hep-ph↗

arXiv2018

Ratios of vector and pseudoscalar $B$ meson decay constants in the light-cone quark model

We study the decay constants of pseudoscalar and vector $B$ meson in the framework of light-cone quark model (LCQM). We apply the variational method to the relativistic Hamiltonian with the Gaussian-type trial wave function to obtain the values of $β$ (scale parameter). Then with the help of known values of constituent quark masses, we obtain the numerical results for the decay constants $f_P$ and $f_V$, respectively. We compare our numerical results with the existing experimental data.

hep-ph↗

arXiv2018

Transverse momentum distributions of electron in simulated QED model

In the present work, we have studied the transverse momentum distributions (TMDs) for the electron in simulated QED model. We have used the overlap representation of light-front wave functions (LFWFs) where the spin-1/2 relativistic composite system consists of spin-1/2 fermion and spin-1 vector boson. The results have been obtained for T-even TMDs in transverse momentum plane for fixed value of longitudinal momentum fraction $x$.

hep-ph↗

arXiv2017

Study of rare semileptonic $B_c^+ \to D^+ ν\barν$ decay in the light-cone quark model

We study the exclusive semileptonic rare $B_c^+ \to D^+ ν\barν$ decay in the framework of light-cone quark model. The transition form factors $f_{+}(q^2)$ and $f_{T}(q^2)$ are evaluated in the time-like region using the analytic continuation method in $q^{+} = 0$ frame. The analytic solutions of these form factors are compared with the results obtained from the double pole parametric form. The branching ratio for $B_c^+ \to D^+ ν\barν$ decay is calculated and compared with the other theoretical model predictions. The predicted results in this model can be tested at the LHCb experiments in near future which will help in testing the unitarity of CKM quark mixing matrix, thus, providing an insight into the phenomenon of CP violation.

hep-ph↗

arXiv2017

Electromagnetic and Axial-Vector Form Factors of the Quarks and Nucleon

In light of the improved precision of the experimental measurements and enormous theoretical progress, the nucleon form factors have been evaluated with an aim to understand how the static properties and dynamical behavior of nucleons emerge from the theory of strong interactions between quarks. We have analysed the vector and axial-vector nucleon form factors ($G^{p,n}_{E,M}(Q^2)$ and $G^{p,n}_{A}(Q^2)$) using the spin observables in the chiral constituent quark model ($χ$CQM) which has made a significant contribution to the unraveling of the internal structure of the nucleon in the nonperturbative regime. We have also presented a comprehensive analysis of the flavor decomposition of the form factors ($G^{q}_{E}(Q^2)$, $G^{q}_{M}(Q^2)$ and $G^{q}_{A}(Q^2)$for $q=u,d,s$) within the framework of $χ$CQM with emphasis on the extraction of the strangeness form factors which are fundamental to determine the spin structure and test the chiral symmetry breaking effects in the nucleon. The $Q^2$ dependence of the vector and axial-vector form factors of the nucleon has been studied using the conventional dipole form of parametrization. The results are in agreement with the available experimental data.

hep-ph↗

arXiv2017

Magnetic Moments of Octet Baryons in Hot and Dense Nuclear Matter

We have calculated the in-medium magnetic moments of octet baryons in the presence of hot and dense symmetric nuclear matter. Effective magnetic moments of baryons have been derived from medium modified quark masses within chiral SU(3) quark mean field model. Further, for better insight of medium modification of baryonic magnetic moments, we have considered the explicit contributions from the valence quarks, sea quarks as well as sea orbital angular momentum of sea quarks. These effects have been successful in giving the description of baryonic magnetic moments in vacuum. The magnetic moments of baryons are found to vary significantly as a function of density of nuclear medium.

hep-ph↗

arXiv2017

Charge and longitudinal momentum distributions in transverse coordinate space

We investigate the charge distributions for the $u$ and $d$ quarks in transverse coordinate space in a light-front quark-diquark model for the nucleons using the overlaps of the wave functions constructed from the soft-wall AdS/QCD prediction. We have also obtained the charge distributions for proton and neutron in transverse coordinate space and compared it with the distributions obtained in impact-parameter space. Further, we study the longitudinal momentum distributions using the wave functions in the transverse coordinate space. We have also shown the explicit fermionic and bosonic contributions for different struck $u$ and $d$ quarks.

hep-ph↗

arXiv2016

Nucleon structure functions and longitudinal spin asymmetries in the chiral quark constituent model

We have analysed the phenomenological dependence of the spin independent ($F_1^{p,n}$ and $F_2^{p,n}$) and the spin dependent ($g_1^{p,n}$) structure functions of the nucleon on the the Bjorken scaling variable $x$ using the unpolarized distribution functions of the quarks $q(x)$ and the polarized distribution functions of the quarks $Δq(x)$ respectively. The chiral constituent quark model ($χ$CQM), which is known to provide a satisfactory explanation of the proton spin crisis and related issues in the nonperturbative regime, has been used to compute explicitly the valence and sea quark flavor distribution functions of $p$ and $n$. In light of the improved precision of the world data, the $p$ and $n$ longitudinal spin asymmetries ($A_1^p(x)$ and $A_1^n(x)$) have been calculated. The implication of the presence of the sea quarks has been discussed for ratio of polarized to unpolarized quark distribution functions for up and down quarks in the $p$ and $n$ $\frac{Δu^p(x)}{u^p(x)}$, $\frac{Δd^p(x)}{d^p(x)}$, $\frac{Δu^n(x)}{u^n(x)}$, and $\frac{Δd^n(x)}{d^n(x)}$. The ratio of the $n$ and $p$ structure functions $R^{np}(x)=\frac{F_2^n(x)}{F_2^p(x)}$ has also been presented. The results have been compared with the recent available experimental observations. The results on the spin sum rule have also been included and compared with data and other recent approaches.

hep-ph↗

arXiv2015

Magnetic moments of $J^P=\frac{3}{2}^+$ decuplet baryons using effective quark masses in chiral constituent quark model

The magnetic moments of $J^P=\frac{3}{2}^+$ decuplet baryons have been calculated in the chiral constituent quark model ($χ$CQM) with explicit results for the contribution coming from the valence quark polarizations, sea quark polarizations, and their orbital angular momentum. Since the $J^P=\frac{3}{2}^+$ decuplet baryons have short lifetimes, the experimental information about them is limited. The $χ$CQM has important implications for chiral symmetry breaking as well as SU(3) symmetry breaking since it works in the region between the QCD confinement scale and the chiral symmetry breaking scale. The predictions in the model not only give a satisfactory fit when compared with the experimental data but also show improvement over the other models. The effect of the confinement on quark masses has also been discussed in detail and the results of $χ$CQM are found to improve further with the inclusion of effective quark masses.

hep-ph↗

arXiv2015

Chiral Odd Generalized Parton Distributions and Spin Densities in the Impact Parameter Space

In the present work we have studied the chiral odd Generalized Parton Distributions (GPDs) in the impact parameter space by assuming a flexible parametrization in a quark-diquark model. In order to obtain the explicit contributions from the up and down quarks, we have considered both the scalar (spin-0) and the axial-vector (spin-1) configurations for the diquark. We have also studied the spin densities for the up and down quarks in this model for monopole, dipole and quadrupole contributions for unpolarized and polarized quarks in unpolarized and polarized proton.

hep-ph↗

arXiv2015

Quark flavor distribution functions for the octet baryons in the chiral quark constituent model

The quark flavor distribution functions of the octet baryons ($N$, $Σ$, $Ξ$ and $Λ$) have been calculated in the chiral constituent quark model ($χ$CQM). In particular, the valence and sea quark flavor distribution functions of the scalar density matrix elements of octet baryons have been computed explicitly. The implications of chiral symmetry breaking and SU(3) symmetry breaking have been discussed in detail for the sea quark asymmetries, fraction of a particular quark (antiquark) present in a baryon, flavor structure functions and the Gottfried integral. The meson-baryon sigma terms $σ_{πB}$, $σ_{K B}$, and $σ_{ηB}$ for the case of $N$, $Σ$ and $Ξ$ baryons have also been calculated. The results have been compared with the recent available experimental observations for the case of $N$ and how the future experiments for $Σ$, $Ξ$ and $Λ$ can provide important constraints to describe the role of non-valence (sea) degrees of freedom has been discussed.

hep-ph↗

arXiv2015

Single Transverse Spin Asymmetries in Semi-inclusive Deep Inelastic Scattering in a Spin-1 Diquark Model

The observed results for the azimuthal single spin asymmetries (SSAs) of the proton, measured in the semi-inclusive deep inelastic scattering (SIDIS), can be explained by the final-state interaction (FSI) from the gluon exchange between the outgoing quark and the target spectator system. SSAs require a phase difference between two amplitudes coupling the target with opposite spins to the same final state. We have used the model of light front wave functions (LFWFs) consisting of a spin-$\frac{1}{2}$ system as a composite of a spin-$\frac{1}{2}$ fermion and a spin-1 vector boson to estimate the SSAs. The implications of such a model have been investigated in detail by considering different coupling constants. The FSIs also produce a complex phase which can be included in the LFWFs to calculate the Sivers and Boer-Mulders distribution functions of the nucleon.

hep-ph↗