Sourendu Gupta

Screening correlators with chiral Fermions (2008)

I review recent developments in finite temperature lattice QCD which are useful for the study of heavy-ion collisions. I pay particular attention to studies of the equation of state and the light...

Gavai, R. V., Gupta, Sourendu, Lacaze, R.

We study screening correlators of quark-antiquark composites at T=2T_c, where T_c is the QCD phase transition temperature, using overlap quarks in the quenched approximation of lattice QCD. As the...

Eigenvalues and Eigenvectors of the Staggered Dirac Operator at Finite Temperature (2008)

Gavai, R. V., Gupta, Sourendu, Lacaze, R.

We examine the eigenvalues and eigenvectors of the staggered Dirac operator on thermal ensembles created in QCD with two flavours of staggered quarks. We see that across the phase transition a gap...

The phase diagram of QCD at small chemical potentials (2007)

Renormalized Polyakov loops in many representations (2007)

We investigate the phase diagram of QCD at small chemical potentials, ie, when chiral and flavour symmetry breaking involves the pairing of a quark and an antiquark. The phase diagram of two-flavour...

Gupta, Sourendu, Hubner, Kay, Kaczmarek, Olaf

We present a renormalization procedure for Polyakov loops which explicitly implements the fact that the renormalization constant depends only on the ultraviolet cutoff. Using this we study the...

Renormalization of Polyakov loops in fundamental and higher representations (2007)

Kaczmarek, Olaf, Gupta, Sourendu, Hubner, Kay

We compare two renormalization procedures, one based on the short distance behavior of heavy quark-antiquark free energies and the other by using bare Polyakov loops at different temporal extent of...

A systematic expansion for relativistic causal hydrodynamics (2007)

Aspects of causal viscous hydrodynamics (2007)

A systematic expansion of the Boltzmann equation for the diffusion of dilute tracers, in powers of the Knudsen number, carried out to next-to-leading order (NLO), gives the relativistic causal...

Bhalerao, R. S., Gupta, Sourendu

We investigate the phenomenology of freely expanding fluids, with different material properties, evolving through the Israel-Stewart (IS) causal viscous hydrodynamics, and compare our results with...

Towards continuum limit of screening lengths with chiral Fermions (2006)

Gavai, Rajiv V., Gupta, Sourendu, Lacaze, Robert

We investigate mesonic screening correlators at T=2T_c using the overlap Fermions in the quenched approximation, where T_c is the QCD phase transition temperature. Using lattices with temporal extent...

The critical end point in QCD (2006)

Lattice QCD Results on Strangeness and Quasi-Quarks in Heavy-Ion Collisions (2006)

In this talk I present the logic behind, and examine the reliability of, estimates of the critical end point (CEP) of QCD using the Taylor expansion method.

Fluctuations, strangeness and quasi-quarks in heavy-ion collisions from lattice QCD (2005)

Fluctuations of conserved quantities in heavy-ion collisions have been argued to be diagnostic tools for the nature of the produced phase. These can be related to the predictions of quark number...

The critical end point of quantum chromodynamics (2005)

We report measurements of diagonal susceptibilities for the baryon number, chi_B, electrical charge, chi_Q, third component of isospin, chi_I, strangeness, chi_S, and hypercharge, chi_Y, as well as...

Gavai, Rajiv, Gupta, Sourendu

We investigate the critical end point (CEP) of QCD with two flavours of light dynamical quarks at finite lattice cutoff a=1/4T using a Taylor expansion of the baryon number susceptibility. We find a...

A new method for computation of QCD thermodynamics: EOS, specific heat and speed of sound (2005)

Gavai, Rajiv V., Gupta, Sourendu, Mukherjee, Swagato

We propose a new variant of the operator method for the computation of the equation of state of QCD, which yields positive pressure for all temperatures and all values of temporal lattice spacings....

Simple patterns for non-linear susceptibilities near T_c (2005)

Dissipation, hydrodynamics and the fireball (2005)

Non-linear susceptibilities upto the eighth order have been constructed in QCD with 2 flavours of dynamical quarks. Beyond leading order, they exhibit peaks at the cross over temperature, T_c. By...

Lattice QCD equation of state : improving the differential method (2005)

We investigate the hydrodynamics of the QCD plasma using dimensionless numbers built from the thermodynamics and transport theory of the plasma and characteristic dimensions of the fireball produced...

Gavai, Rajiv V., Gupta, Sourendu, Mukherjee, Swagato

We propose an improvement of the differential method for the computation of the equation of state of QCD from lattice simulations. In contrast to the earlier differential method our technique yields...

A transport coefficient: the electrical conductivity (2005)

Quark Number Susceptibilities & The Wroblewski Parameter (2005)

I describe the lattice determination of the electrical conductivity of the quark gluon plasma. Since this is the first extraction of a transport coefficient with a degree of control over errors, I...

The critical end point of QCD (2004)

The Wroblewski parameter is a convenient indicator of strangeness production and can be employed to monitor a signal of quark-gluon plasma production : enhancement of strangeness production. It has...

The speed of sound and specific heat in the QCD plasma: hydrodynamics, fluctuations and conformal symmetry (2004)

We investigate the critical end point of QCD with two flavours of light dynamical quarks at finite lattice cutoff a=1/4T using a Taylor expansion of the baryon number susceptibility. We find a strong...

Gavai, Rajiv V., Gupta, Sourendu, Mukherjee, Swagato

We report the continuum limits of the speed of sound, c_s, and the specific heat at constant volume, c_v, in quenched QCD at temperatures of 2Tc and 3Tc. At these temperatures, c_s is within 2-sigma...

Here's looking at you, fireball (2004)

Chiral dynamics in QCD at finite chemical potential (2004)

Plasmas screen electromagnetic waves of frequency less than the plasma frequency, omega_p, with a skin depth, delta, specified by the electrical conductivity, sigma. Current estimates of the...

Gupta, Sourendu, Ray, R.

We present the renormalized Taylor expansion of the chiral condensate with chemical potential. The relation with the Taylor coefficients of meson susceptibilities and the quark mass dependence of the...

The Wroblewski Parameter from Lattice QCD (2004)

Taylor expansions in chemical potential (2003)

Enhancement of strangeness production has since long been proposed as a promising signal of quark-gluon plasma production. A convenient indicator for it is the Wroblewski parameter which has been...

Gavai, Rajiv, Gupta, Sourendu, Roy, Rajarshi

Properties of QCD at finite chemical potential are extracted using Taylor series expansions. The continuum limits of lattice results are presented. The result of expanding the free energy density,...

Pressure and non-linear quark number susceptibilities in QCD (2003)

Analyticity and the phase diagram of QCD (2003)

We report the first measurements of sixth order non-linear quark number susceptibilities in continuum QCD. This extends our earlier computation of the continuum limit of non-linear quark number...

Pressure and non-linear susceptibilities in QCD at finite chemical potentials (2003)

Some consequences of the analyticity of the free energy (pressure) of QCD at finite chemical potential are deduced. These include a method for numerical exploration of the full phase diagram by a...

The Quark Gluon Plasma: lattice computations put to experimental test (2003)

When the free energy density of QCD is expanded in a series in the chemical potential, mu, the Taylor coefficients are the non-linear quark number susceptibilities. We show that these depend on the...

The electrical conductivity and soft photon emissivity of the QCD plasma (2003)

I describe how lattice computations are being used to extract experimentally relevant features of the quark gluon plasma. I deal specifically with relaxation times, photon emissivity, strangeness...

Lattice QCD for RHIC (2002)

The electrical conductivity in the hot phase of the QCD plasma is extracted from a quenched lattice measurement of the Euclidean time vector correlator for 1.5 < T/T_c < 3. The spectral density in...

Valence quarks in the QCD plasma: quark number susceptibilities and screening (2002)

I briefly introduce the methods by which lattice QCD predictions for RHIC are obtained. Next I deal with lattice determinations of strangeness production and event-to-event fluctuations of conserved...

The phase transition in QCD with broken SU(2) flavour symmetry (2002)

We have investigated the quark sector of quenched QCD for 1.5\le T/Tc\le3 in the continuum limit, using two different lattice discretisations of quarks and extrapolating from lattice spacings between...

Does the QCD plasma contain propagating gluons? (2002)

We report the first investigation of the QCD transition temperature, T_c, for two flavours of staggered quarks with unequal masses at lattice spacings of 1/4T. On changing the u/d quark mass ratio in...

Speed and Adaptability of Overlap Fermion Algorithms (2002)

Comparison of two appropriately chosen screening masses of colour singlet operators in the pure glue QCD plasma indicates that at sufficiently high temperature it contains a weakly-interacting...

Gavai, Rajiv V., Gupta, Sourendu, Lacaze, Robert

We compare the efficiency of four different algorithms to compute the overlap Dirac operator, both for the speed, i.e., time required to reach a desired numerical accuracy, and for the adaptability,...

Critical behaviour in QCD at finite isovector chemical potential (2002)

The continuum limit of quark number susceptibilities (2002)

We report an investigation of criticality in QCD at finite isovector chemical potential, mu_3, and at zero temperature. At the critical point, mu_3^c = m_pi, we find that an uncharged scalar and...

Susceptibilities and screening masses in two flavor QCD (2001)

We report the continuum limit of quark number susceptibilities in quenched QCD. Deviations from ideal gas behaviour at temperature T increase as the lattice spacing is decreased from T/4 to T/6, but...

Gavai, Rajiv V., Gupta, Sourendu, Majumdar, Pushan

We studied QCD with two flavors of dynamical staggered quarks at finite temperature, with a bare sea quark mass of about 17 MeV. We report investigations of baryon, isospin, charge and strangeness...

Quenched QCD at finite temperature with overlap Fermions (2001)

Gavai, R. V., Gupta, Sourendu, Lacaze, R.

We study quenched QCD just above the phase transition temperature using overlap Fermions. Exact zero modes of the overlap operator are localized. Chiral symmetry is restored, as indicated by the...

Finite-size Scaling at Phase Coexistence (2001)

Sourendu Gupta, A. Irback, M. Ohlsson

From a finite-size scaling (FSS) theory of cumulants of the order parameter at phase coexistence points, we reconstruct the scaling of the moments. Assuming that the cumulants allow a reconstruction...

Quenched QCD at finite temperature with chiral Fermions (2001)

Gavai, Rajiv V., Gupta, Sourendu, Lacaze, R.

We study physics at temperatures just above the QCD phase transition (Tc) using chiral (overlap) Fermions in the quenched approximation of lattice QCD. Exact zero modes of the overlap Dirac operator...

Quark number susceptibilities, strangeness and dynamical confinement (2001)

Obstructions to dimensional reduction in hot QCD (2000)

We report first results on the strange quark number susceptibility, chi_s, over a large range of temperatures, mainly in the plasma phase of QCD. Chi_s jumps across the phase transition temperature,...

A precise determination of T_c in QCD from scaling (2000)

I describe results on screening masses in hot gauge theories. Wilsonian effective long distance theories called dimensionally reduced (DR) theories describe very well the longest screening length in...

Fermions obstruct dimensional reduction in hot QCD (2000)

Existing lattice data on the QCD phase transition are analyzed in renormalized perturbation theory. In quenched QCD it is found that T_c scales for lattices with only 3 time slices, and that...

QCD Working Group Report (2000)

We have studied, for the first time, screening masses obtained from glueball-like correlators in Quantum Chromodynamics with four light dynamical flavours of quarks in the temperature range 1.5T_c <...

Banerjee, S., Basu, R., Dittmar, M., Gavai, R. V., Gelis, F., Ghosh, D., ...

This is the report of the QCD working group at WHEPP 6. Discussions and work on heavy ion collisions, polarised scattering, and collider phenomenology are reported.

A QCD Analysis of Polarised Parton Densities (2000)

Ghosh, Dilip Kumar, Gupta, Sourendu, Indumathi, D.

We present the results of a QCD fit to global data on deep-inelastic polarised lepton-hadron scattering. We find that it is possible to fit the data with strongly broken SU(2) flavour for the...

Screening Masses in SU(2) Pure Gauge Theory (1999)

Probing the quark-gluon plasma with a new Fermionic correlator (1999)

We perform a systematic scaling study of screening masses in pure gauge SU(2) theory at temperatures above the phase transition temperature. The major finite volume effect is seen to be spatial...

Representations of Fermionic Correlators at Finite Temperatures (1999)

We present the first measurement of a new correlation function of Fermion bilinears in finite temperature QCD with and without dynamical quarks in a quantum number channel in which non-trivial...

Double Asymptotic Scaling in Drell-Yan Processes (1998)

The symmetry group of the staggered Fermion transfer matrix in a spatial direction is constructed at finite temperature. Hadron-like operators carrying irreducible representations of this group are...

Basu, Rahul, Gupta, Sourendu

Double scaling may be observed in the Drell-Yan process at the Tevatron and in the ALICE detector at the Large Hadron Collider in a window of masses. In the double scaling limit of the cross section,...

Dimensional Reduction in High Temperature Gauge Theories (1998)

Dimensional Reduction and Screening Masses in Pure Gauge Theories at Finite Temperature (1998)

Screening masses in the equilibrium thermodynamics of gauge theories were measured. The spectroscopy of these screening masses gives strong evidence for dimensional reduction at $T\ge2T_c$. A...

Thermal Effects on Two-photon Decays of Pseudo-scalars (1998)

We studied screening masses in the equilibrium thermodynamics of SU(2) and SU(3) pure gauge theories on the lattice. At a temperature of 2 Tc we found strong evidence for dimensional reduction in the...

Sourendu Gupta, S. N. Nayak

We study the effect of finite temperatures and Fermion density on the effective pseudo-scalar-photon vertex induced by the triangle diagram. The manifestly covariant calculations show that when the...

Jet Missing Transverse Momenta For Quark-Gluon Plasma Thermometry (1998)

Sourendu Gupta

At the LHC, where hard multi-jet events are common, large imbalances in the total jet-p T can arise due to the interaction of jets with the plasma formed in heavy-ion collisions. We find that this...

Quarkonium Polarization in Non-relativistic QCD and the Quark-Gluon Plasma (1998)

Polarised and Unpolarised Charmonium Production at Higher Orders in v (1997)

We examine angular distributions of leptons arising from the decay of J/psi in inclusive hadroproduction. Taking into account feed-down contributions from chi_{1,2}, a flat distribution emerges...

Single Polarisation Asymmetries for Quarkonia in Non-relativistic QCD (1997)

We study the unpolarised and polarised hadro-production of charmonium in non-relativistic QCD (NRQCD) at low transverse momentum, including sufficiently higher orders in the relative velocity, $v$,...

and Polarisation Asymmetries for Quarkonia at High Orders in Non-relativistic QCD (1997)

We find that single spin asymmetries in NRQCD are non-vanishing in general. They are proportional to the imaginary parts of some non-perturbative matrix elements. With statistics of about 10^6...

Sourendu Gupta

We study doubly polarised asymmetries of ¯ cc and ¯ bb mesons in hadro- and photo-production at low transverse momentum in nonrelativistic QCD to high orders in the relative velocity of the pair,...

Chi_1 and Polarisation Asymmetries for Quarkonia at High Orders in Non-relativistic QCD (1997)

Higher Orders in the Colour-Octet Model of J/\psi Production (1997)

We study doubly polarised asymmetries of c-cbar and b-bbar mesons in hadro- and photo-production at low transverse momentum in non-relativistic QCD to high orders in the relative velocity of the...

Is there Anomalous J/psi Suppression in Present-day Heavy-ion Collisions? (1997)

We study the hadro- and photo-production of $\bar cc$ and $\bar bb$ mesons at low transverse momentum to high orders in the relative velocity of the pair, v, in non-relativistic QCD. We evaluate...

Thermal Effects on Two-photon Decays of Pseudo-scalars (1997)

We re-analyse the data on J/psi cross sections for proton-nucleus and nucleus-nucleus collisions obtained by the CERN experiments NA38, NA51 and NA50. Our systematic analysis of error propagation...

Gupta, Sourendu, Nayak, S. N.

We study the effect of finite temperatures and Fermion density on the effective pseudo-scalar-photon vertex induced by the triangle diagram. The manifestly covariant calculations show that when the...

J/psi Spin Asymmetries in the Colour-Octet Model (1996)

Collinear Divergences at One-loop Order for External Particles in a Heat-bath (1996)

We investigate the pattern of asymmetries in the colour-octet model for inclusive production of charmonium with polarised initial state hadrons and photons. We find that singly polarised asymmetries...

Datta, Saumen, Gupta, Sourendu, Ravindran, V.

In hard interactions between external particles incident on a heat-bath, we show that large logarithms are generated when a radiated or absorbed gauge boson is collinear with the initial fermion...

Colour-octet Contributions to $x_F$ Distributions in $J/\psi$ Hadro-production at Fixed Target Energies (1996)

Gupta, Sourendu, Sridhar, K.

We study J/\psi production at fixed-target energies, including the colour-octet production mechanisms predicted by NRQCD. In an earlier paper, we found that the octet components were crucial in...

Finite-size Scaling at Phase Coexistence (1996)

Sourendu Gupta, M. Ohlsson

From a finite-size scaling (FSS) theory of cumulants of the order parameter at phase coexistence points, we reconstruct the scaling of the moments. Assuming that the cumulants allow a reconstruction...

Colour-octet Contributions to J/psi Hadroproduction at Fixed Target Energies (1996)

Gupta, Sourendu, Sridhar, K.

We investigate the integrated cross section for forward $\jpsi$ production in proton-proton and pion-proton collisions at centre of mass energies upto 60 GeV. We find that colour-octet contributions...

Bloch-Nordsieck Thermometers: One-loop Exponentiation in Finite Temperature QED (1995)

Gupta, Sourendu, Indumathi, D., Mathews, P., Ravindran, V.

We study the scattering of hard external particles in a heat bath in a real-time formalism for finite temperature QED. We investigate the distribution of the 4-momentum difference of initial and...

Bloch-Nordsieck Thermometers: One-loop Exponentiation in Finite Temperature QED (1995)

Gupta, Sourendu, Indumathi, D, Mathews, P, Ravindran, V

We study the scattering of hard external particles in a heat bath in a real-time formalism for finite temperature QED. We investigate the distribution of the 4-momentum difference of initial and...

Hadron Properties just before Deconfinement (1995)

Boyd, G., Gupta, Sourendu, Karsch, F., Laermann, E., Petersson, B., Redlich, K.

We have investigated hadron screening masses, the chiral condensate, and the pion decay constant close to the deconfinement phase transition in the confined phase of QCD. The simulations were done in...

Jet Missing PT for Quark-Gluon Plasma Thermometry (1995)

Bloch-Nordsieck Thermometers: One-loop Exponentiation in Finite Temperature QED (1995)

At the LHC, where hard multi-jet events are common, large imbalances in the total jet-\pt{} can arise due to the interaction of jets with the plasma formed in heavy-ion collisions. We find that this...

Gupta, Sourendu, Indumathi, D, Mathews, P, Ravindran, V

We study the scattering of hard external particles in a heat bath in a real-time formalism for finite temperature QED. We investigate the distribution of the 4-momentum difference of initial and...

Spatial and Temporal Hadron Correlators below and above the Chiral Phase Transition (1994)

Boyd, G., Gupta, Sourendu, Karsch, F., Laermann, E.

Hadronic correlation functions at finite temperature in QCD, with four flavours of dynamical quarks, have been analyzed both above and below the chiral symmetry restoration temperature. We have used...

Interface Tensions and Perfect Wetting in the Two-Dimensional Seven-State Potts Model (1993)

Grossmann, B., Gupta, Sourendu

We present a numerical determination of the order-disorder interface tension, \sod, for the two-dimensional seven-state Potts model. We find $\sod=0.0114\pm0.0012$, in good agreement with...

Instantons and Surface Tension at a First-Order Transition (1993)

Glueball-Like Screening Masses in Pure SU(3) at Finite Temperatures (1993)

We study the dynamics of the first order phase transition in the two dimensional 15-state Potts model, both at and off equilibrium. We find that phase changes take place through nucleation in both...

Grossman, B., Gupta, Sourendu, Heller, U. M., Karsch, F.

We investigate the finite-temperature excitation spectrum in the gluon sector of $SU(3)$ pure gauge theory through measurements of screening masses in correlations of loop operators. We develop the...

Electromagnetic Signals and Backgrounds in Heavy-Ion Collisions: (1993)

Finite-Size Scaling at Phase Coexistence (1993)

Aspects of the dilepton spectrum in heavy-ion collisions are discussed, with special emphasis on using lattice computations to guide the phenomenology of finite temperature hadronic matter. The...

Gupta, Sourendu, Irbaeck, A., Ohlsson, M.

{}From a finite-size scaling (FSS) theory of cumulants of the order parameter at phase coexistence points, we reconstruct the scaling of the moments. Assuming that the cumulants allow a...

Critical Hysteresis (1993)

The Degrees of Freedom in Hot Quenched QCD (1992)

Hysteresis is observed at second order phase transitions. Universal scaling formul\ae{} for the areas of hysteresis loops are written down. Critical exponents are defined, and related to other...