Raktim Abir

Soft gluon emission off a heavy quark revisited

An improved generalized suppression factor for gluon emission off a heavy quark is derived within perturbative QCD, which is valid for the full range of rapidity of the radiated gluon and also has no restriction on the scaled mass of the quark with its energy. In the appropriate limit it correctly reproduces the usual dead cone factor in the forward rapidity region. On the other hand, this improved suppression factor becomes close to unity in the backward direction. This indicates a small suppression of gluon emission in the backward region, which should have an impact on the phenomenology of heavy quark energy loss in the hot and dense matter produced in ultra-relativistic heavy-ion collisions.

The consequences of SU (3) colorsingletness, Polyakov Loop and Z (3) symmetry on a quark–gluon gas

Based on quantum statistical mechanics we show that the SU(3) color singlet ensemble of a quark-gluon gas exhibits a Z(3) symmetry through the normaized character in fundamental representation and also becomes equivalent, within a stationary point approximation, to the ensemble given by Polyakov Loop. Also Polyakov Loop gauge potential is obtained by considering spatial gluons along with the invariant Haar measure at each space point. The probability of the normalized character in SU(3) vis-a-vis Polyakov Loop is found to be maximum at a particular value exhibiting a strong color correlation. This clearly indicates a transition from a color correlated to uncorrelated phase or vise-versa. When quarks are included to the gauge fields, a metastable state appears in the temperature range 145 T(MeV) 170 due to the explicit Z(3) symmetry breaking in the quark-gluon system. Beyond T 170 MeV the metastable state disappears and stable domains appear. At low temperature a dynamical recombination of ionized Z(3) color charges to a color singlet Z(3) confined phase is evident along with a confining background that originates due to circulation of two virtual spatial gluons but with conjugate Z(3) phases in a closed loop. We also discuss other possible consequences of the center domains in the color deconfined phase at high temperature.

Solution of the linearized Balitsky-Kovchegov equation

We revisited solution of a linearized form of leading order Balitsky-Kovchegov equation (linear in S-matrix for dipole-nucleus scattering). Here we adopted dipole transverse width dependent cutoff in order to regulate the dipole integral. We also have taken care of all the higher order terms (higher order in the cutoff) that have been reasonably neglected before. The solution reproduces both McLerran-Venugopalan type initial condition (Gaussian in scaling variable) and Levin-Tuchin solution (Gaussian in logarithm of scaling variable) in the appropriate limits. It also connects this two opposite limits smoothly with better accuracy for sets of rescaled rapidity when compared to numerical solutions of full leading order Balitsky-Kovchegov equation.

arXiv : Unintegrated dipole gluon distribution at small transverse momentum

We derive analytical results for unintegrated color dipole gluon distribution function at small transverse momentum. By Fourier transforming the

Drag induced radiative energy loss of semi-hard heavy quarks

S

Soft Gluon Radiation off Heavy Quarks beyond Eikonal Approximation

-matrix for large dipoles we derive the results in the form of a series of Bells polynomials. Interestingly, when resumming the series in leading log accuracy, the results showing up striking similarity with the Sudakov form factor with role play of coupling is being done by a constant that stems from the saddle point condition along the saturation line.

Gluon Radiation Off Heavy Flavour Jets

We revisited gluon bremsstrahlung off a heavy quark in nuclear matter within higher twist formalism. In this work, we demonstrate that, in addition to transverse momentum diffusion parameter (

Color-singlet clustering of partons and recombination model for hadronization of quark-gluon plasma

\hat q

Generalization of Gunion-Bertsch formula for soft gluon emission

), the gluon emission spectrum for a heavy quark is quite sensitive to

Drag-induced radiative energy loss from semihard heavy quarks

\hat e