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Abhee K. Dutt-Mazumder

Publications and source records attributed to Abhee K. Dutt-Mazumder.

At least 37 records · Page 2Linked to original sources
arXiv2008

Fermi Liquid parameters for dense nuclear matter in Effective Chiral Model

We calculate relativistic Fermi liquid parameters (RFLPs) for the description of the properties of dense nuclear matter (DNM) using Effective Chiral Model. Analytical expressions of Fermi liquid parameters (FLPs) are presented both for the direct and exchange contributions. We present a comparative study of perturbative calculation with mean field (MF) results. Moreover we go beyond the MF so as to estimate the pionic contribution to the FLPs. Finally, we use these parameters to estimate some of the bulk quantities like incompressibility, sound velocity, symmetry energy etc. for DNM interacting via exchange of $σ$, $ω$ and $π$ meson. In addition, we also calculate the energy densities and the binding energy curve for the nuclear matter. Results for the latter have been found to be consistent with two loop calculations reported recently within the same model.

hep-ph↗
arXiv2008

Matter induced charge symmetry breaking and pion form factor in nuclear medium

Medium modification of pion form factor has been evaluated in asymmetric nuclear matter. It is shown that both the shape and the pole position of the pion form factor in dense asymmetric nuclear matter is different from its vacuum counterpart with $ρ$-$ω$ mixing. This is due to the density and asymmetry dependent $ρ$-$ω$ mixing which could even dominate over its vacuum counterpart in matter. Effect of the in-medium pion factor on experimental observables {\it e.g.}, invariant mass distribution of lepton pairs has been demonstrated.

nucl-th↗
arXiv2008

Effects of Dirac sea on pion propagation in asymmetric nuclear matter

We study pion propagation in asymmetric nuclear matter (ANM). One of the interesting consequences of pion propagation in ANM is the mode splitting for the different charged states of pions. First we describe the pion-nucleon dynamics using the non-chiral model where one starts with pseudoscalar (PS) $π$N coupling and the pseudovector (PV) representation is obtained via suitable non-linear field transformations. For both of these cases the effect of the Dirac sea is estimated. Subsequently, we present results using the chiral effective Lagrangian where the short-distance behavior (Dirac vacuum) is included by re-defining the field parameters as done in the modern effective field theory approach developed recently. The results are compared with the previous calculations for the case of symmetric nuclear matter (SNM). Closed form analytical results are presented for the effective pion masses and dispersion relations by making hard nucleon loop (HNL) approximation and suitable density expansion.

nucl-th↗
arXiv2007

Thermal Radiation from Au + Au Collisions at \sqrt{s} = 200 GEV/A Energy

The transverse momentum distribution of the direct photons measured by the PHENIX collaboration in $Au + Au$ collisions at $\sqrt{s}=200$ GeV/A has been analyzed. It has been shown that the data can be reproduced reasonably well assuming a deconfined state of thermalized quarks and gluons with initial temperature more than the transition temperature for deconfinement inferred from lattice QCD. The value of the initial temperature depends on the equation of state of the evolving matter. The sensitivities of the results on various input parameters have been studied. The effects of the modifications of hadronic properties at non-zero temperature have been discussed.

nucl-th↗
arXiv2006

Isospin mode splitting and mixing in asymmetric nuclear matter

We estimate exclusive density and asymmetry parameter dependent dispersion relations of various charged states of pions in asymmetric nuclear matter. The possibility of matter induced mixing of $π^0$ with $η$ is clearly exposed with the further mass modification of $π^0$ meson due to mixing. Asymmetry driven mass splitting and mixing amplitude are of the same order as the corresponding values in vacuum. Closed form analytic results for the mass shifts and dispersion relations with and without mixing are presented. Furthermore, we discuss the sensitivity of our results on the scalar mean field within the framework of Quantum Hadrodynamics.

nucl-th↗
arXiv2006

Collisional energy loss and the suppression of high $p_T$ hadrons

We calculate nuclear suppression factor ($R_{AA}$) for light hadrons by taking only the elastic processes and argue that in the measured $p_T$ domain of RHIC, collisional rather than the radiative processes is the dominant mechanism for partonic energy loss.

nucl-th↗
arXiv2006

Energy loss and dynamical evolution of quark $p_T$ spectra

Average energy loss of light quarks has been calculated in a two stage equilibrium scenario where the quarks are executing Brownian motion in a gluonic heat bath. The evolution of the quark $p_T$ spectra is studied by solving Fokker-Planck equation in an expanding plasma. Results are finally compared with experimentally measured pion $p_T$ spectrum at RHIC.

hep-ph↗
arXiv2006

Can collisional energy loss explain nuclear suppression factor for light hadrons ?

We argue that in the measured $p_T$ domain of RHIC, collisional rather than the radiative energy loss is the dominant mechanism for jet quenching. Accordingly we calculate nuclear suppression factor for light hadrons by taking only the elastic energy loss in sharp contrast with the previous calculations where only the radiative loss are considered.

hep-ph↗
arXiv2005

Kaon to Pion ratio in Heavy Ion Collisions

The momentum integrated Boltzmann equation has been used to study the evolution of strangeness of the strongly interacting system formed after the heavy ion collisions at relativistic energies.We argue that the experimentally observed non-monotonic, horn-like structure in the variation of the $K^+/π^+$ with colliding energy appears due to the release of large number of colour degrees of freedom.

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arXiv2005

phi production at RHIC: characterization of co-existence phase

We extract the effective degrees of freedom that characterize the co-existing phase of quark gluon plasma and hadrons. Experimental data on phi at mid-rapidity is used to set a lower bound to the critical temperature of quark hadron phase transition. The production and evolution of strangeness have been studied by using Boltzmann equation. The results have been contrasted with the experimental data obtained by STAR collaboration at RHIC for Au + Au collisions at sqrt{s_{NN}}=200 GeV. Our study reveals that the phi mesons freeze out at a temperature ~ 160 MeV, a value close to the transition temperature for quark-hadron phase transition.

nucl-th↗
arXiv2005

Charmonium Productions: Nucleon-Nucleon versus Nucleus-Nucleus Collisions

Charmonium productions in $p-p$ and $A-B$ collisions have been estimated within the ambit of colour evaporation model (CEM). The model parameters have been fixed by fitting the theoretical results with CDF data. The method is then applied to RHIC and LHC energies to obtain the transverse momentum distributions of $J/ψ$, $ψ^{\prime}$ and $χ_c$. Suppression due to Debye screening in a quark gluon plasma (QGP) is estimated at various centrality cuts. The final $p_T$ distributions of various resonances are then predicted convoluting with the survival probability.

nucl-th↗
arXiv2005

Stopping power of hot QCD plasma

The partonic energy loss has been calculated taking both the hard and soft contributions for all the $2 \to 2$ processes, revealing the importance of the individual channels. Cancellation of the intermediate separation scale has been exhibited. Subtleties related to the identical final state partons have properly been taken into account. The estimated collisional loss is compared with its radiative counter part. We show that there exists a critical energy ($E_c$) below which the collisional loss is more than its radiative counterpart. In addition, we present closed form formulas for both the collision probabilities and the stopping power ($dE/dx$)

hep-ph↗
arXiv2004

Charmonium at LHC: Production, Propagation and Decay

The productions of muon pairs from the decay of heavy quarkonia have been evaluated for different centrality of the nuclear collisions at LHC energies. The effects of the various comover scenarios on the survival probability of the heavy quarkonia have been considered. The effects of shadowing and comover suppressions on the dilepton spectra originating from the decays of J/ψis found to be substantial. The dilepton yield from the thermal J/ψhas also been estimated and found to be small.

nucl-th↗
arXiv2002

Omega meson propagation in dense nuclear matter and collective excitations

The bosonic excitations induced by the omega meson propagation in dense nuclear matter is studied within the framework of random phase approximation. The collective modes are then analyzed by finding the zeros of the relevant dielectric functions. Subsequently we present closed form analytical expressions for the dispersion relations in different kinematical regime. Next, the analytical behaviour of the in-medium effective propagator for the omega meson is examined. This is exploited to calculate the full spectral function for the transverse (T) and longitudinal (L) mode of the omega meson. In addition, various sum rules are constructed for the omega meson spectral density in nuclear medium. Results are then discussed by calculating residues at the poles and discontinuities across the cuts.

nucl-th↗
arXiv2000

Rho-omega mixing in asymmetric nuclear matter via QCD sum rule approach

We evaluate the operator product expansion (OPE) for a mixed correlator of the isovector and isoscalar vector currents in the background of the nucleon density with intrinsic isospin asymmetry [i.e. excess of neutrons over protons] and match it with its imaginary part, given by resonances and continuum, via the dispersion relation. The leading density-dependent contribution to $ρ-ω$ mixing is due the scattering term, which turns out to be larger than any density dependent piece in the OPE. We estimate that the asymmetric density of $n_n-n_p \sim 2.5 \times 10^{-2} ~{\rm fm^3}$ induces the amplitude of $ρ-ω$ mixing, equal in magnitude to the mixing amplitude in vacuum, with the constructive interference for positive and destructive for negative values of $n_n-n_p$. We revisit sum rules for vector meson masses at finite nucleon density to point out the numerical importance of the screening term in the isoscalar channel, which turns out to be one order of magnitude larger than any density-dependent condensates over the Borel window. This changes the conclusions about the density dependence of $m_ω$, indicating $\sim 40$ MeV increase at nuclear saturation density.

hep-ph↗
arXiv1998

Photons from Hadronic Matter at Finite Temperature

Temperature dependence of hadronic decay widths and masses are studied within the framework of an effective Lagrangian approach. At finite temperature the hadronic masses do not seem to follow a universal scaling law. Considering an exhaustive set of hadronic reactions and vector meson decays we have estimated the photon spectrum emitted from hot hadronic matter taking into account medium effects through thermal loop corrections on the hadronic decay widths and masses. An enhancement in photon emission rate is obtained when we use the in-medium masses of vector mesons in our calculations. It is observed that the effect of $ρ$ decay width on the photon spectra is negligible.

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arXiv1997

The decay of the omega meson at finite temperature

The decay width of the $ω$ meson at finite temperature is calculated using the Gell-Mann Sharp Wagner model of $ρ$ pole dominance. Effective masses of the $ρ$ and $ω$ are determined within the framework of real-time formalism of finite temperature field theory. It is shown that even though the mass of the $ω$-meson decreases with temperature, its decay width increases because of an interesting interplay between the phase space factors, the transition matrix element and Bose enhancement.

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