The QCD EoS from simulations on BlueGene L Supercomputers at LLNL and NYBlue (2008)
We present results for the QCD Equation of State (EoS) obtained using simulations of lattice QCD at zero chemical potential. Our high statistics results compare improved asqtad and p4fat3 staggered...
Toward a precise determination of Tc with 2+1 flavors of quarks (2007)
DeTar, Carleton, Gupta, Rajan, Collaboration, For The HotQCD
We present a status report on a new high statistics study of the high temperature transition in full QCD at zero chemical potential. Our simulations use both improved asqtad and p4 staggered quarks...
Improved bilinears in lattice QCD with non-degenerate quarks (2005)
Bhattacharya, Tanmoy, Gupta, Rajan, Lee, Weonjong, Sharpe, Stephen R., Wu, Jackson M. S.
We describe the extension of the improvement program for bilinear operators composed of Wilson fermions to non-degenerate dynamical quarks. We consider two, three and four flavors, and both flavor...
Towards a chiral gauge theory by deconstruction in AdS5 (2005)
Bhattacharya, Tanmoy, Gupta, Rajan, Martin, Matthew R., Shirman, Yuri, Csaki, Csaba, Terning, John
We describe an implementation of a deconstructed gauge theory with charged fermions defined on an interval in five dimensional AdS space. The four dimensional slices are Minkowski, and the end slices...
Scaling behavior of discretization errors in renormalization and improvement constants (2005)
Bhattacharya, Tanmoy, Gupta, Rajan, Lee, Weonjong, Sharpe, Stephen R.
Non-perturbative results for improvement and renormalization constants needed for on-shell and off-shell O(a) improvement of bilinear operators composed of Wilson fermions are presented. The...
Phenomenology using lattice QCD (2005)
This talk provides a brief summary of the status of lattice QCD calculations of the light quark masses and the kaon bag parameter B_K. Precise estimates of these four fundamental parameters of the...
Calculating $\epsilon'/\epsilon$ using HYP staggered fermions (2004)
Bhattacharya, Tanmoy, Fleming, George T., Gupta, Rajan, Kilcup, Greg, Lee, Weonjong, Sharpe, Stephen
We present preliminary results for $\epsilon'/\epsilon$ calculated using HYP staggered fermions in the quenched approximation. We compare different choices of quenched penguin operators.
Testing improved staggered fermions with $m_s$ and $B_K$ (2004)
Lee, Weonjong, Bhattacharya, Tanmoy, Fleming, George T., Gupta, Rajan, Kilcup, Gregory, Sharpe, Stephen R.
We study the improvement of staggered fermions using hypercubically smeared (HYP) links. We calculate the strange quark mass and the kaon B-parameter, $B_K$, in quenched QCD on a $16^3 \times 64$...
Estimates of Light Quark Masses from Lattice QCD and QCD Sum rules (2003)
This talk reviews the progress made in the determination of the light quark masses using lattice QCD and QCD sum rules. Based on preliminary calculations with three flavors of dynamical quarks, the...
Improved bilinears in unquenched lattice QCD (2003)
Bhattacharya, Tanmoy, Gupta, Rajan, Lee, Weonjong, Sharpe, Stephen R., Wu, Jackson M. S.
We summarize the extent to which one can use Ward identities to non-perturbatively improve flavor singlet and non-singlet bilinears with three flavors of non-degenerate dynamical Wilson-like fermions.
Status of B_K from Lattice QCD (2003)
A brief review of lattice calculations of the bag parameter B_K relevant for understanding indirect CP violation in the neutral kaon sector is given. A status report on current state-of-the-art...
Health, education and employment in India (2002)
a land of opulence, tragedy and hope. Rajan Gupta is a theoretical physicist at Los Alamos Laboratory. He has developed lectures on HIV/AIDS awareness and prevention aimed at students, health...
Renormalization constants using quark states in Landau gauge (2001)
Bhattacharya, Tanmoy, Gupta, Rajan, Lee, Weonjong
We show that given one O(a) improvement constant, b_m, all the remaining quantities needed to define the renormalized and O(a) improved dimension-3 quark bilinears can be obtained by studying the...
Scaling behavior of improvement and renormalization constants (2001)
Bhattacharya, Tanmoy, Gupta, Rajan, Lee, Weonjong, Sharpe, Stephen
This talk summarizes results for all the scale independent renormalization constants for bilinear currents ($Z_A$, $Z_V$, and $Z_S/Z_P$), the improvement constants ($c_A$, $c_V$, and $c_T$), the...
Renormalization Constants using Quark States in Fixed Gauge (2001)
Bhattacharya, Tanmoy, Gupta, Rajan, Lee, Weonjong
We present a status report on our calculation of the renormalization constants for the quark bilinears in quenched (O(a)) improved Wilson theory at (beta=6.4) using quark states in Landau gauge.
Light quark masses: a status report at DPF 2000 (2001)
A summary of the extraction of light quark masses from both QCD sumrules and lattice QCD simulations is presented. The focus is on providing a careful statement of the potential weaknesses in each...
Improvement and Renormalization Constants in O(a) Improved Lattice QCD (2001)
Bhattacharya, Tanmoy, Gupta, Rajan, Lee, Weonjong, Sharpe, Stephen
We present results at beta=6.0 and 6.2 for the O(a) improvement and renormalization constants for bilinear operators using axial and vector Ward identities. We discuss the extraction of the mass...
Order a improved renormalization constants (2000)
Bhattacharya, Tanmoy, Gupta, Rajan, Lee, Weonjong, Sharpe, Stephen
We present non-perturbative results for the constants needed for on-shell $O(a)$ improvement of bilinear operators composed of Wilson fermions. We work at $\beta=6.0$ and 6.2 in the quenched...
Fixed-point pure gauge action using $ b= \sqrt{3} $ RGT (1999)
Bhattacharya, Tanmoy, Gupta, Rajan, Lee, Weonjong
We present a status report on the construction of the classical perfect action using the $ b=\sqrt{3} $ renormalization group transformation (RGT). We investigate finite volume corrections and map...
Spectrum of Mesons and Baryons with $b$ Quarks (1999)
We present highlights of the spectrum of mesons and baryons calculated using NRQCD for heavy quarks and tadpole improved clover action for the light quarks.
Prospects of calculating $\epsilon_K$ and $\epsilon'$ from lattice QCD (1999)
An overview of lattice results for the strange quark mass, $B_K$, $B_6$, $B_7$, and $B_8$ is presented. I give my assessment of the reliability of various estimates and prospects for future...
General Physics Motivations for Numerical Simulations of Quantum Field Theory (1999)
In this introductory article a brief description of Quantum Field Theories (QFT) is presented with emphasis on the distinction between strongly and weakly coupled theories. A case is made for using...
Non-perturbative Renormalization Constants using Ward Identities (1999)
Bhattacharya, Tanmoy, Chandrasekharan, Shailesh, Gupta, Rajan, Lee, Weonjong, Sharpe, Stephen
We extend the application of axial Ward identities to calculate $b_A, b_P$ and $b_T$, coefficients that give the mass dependence of the renormalization constants of the corresponding bilinear...
Phase separation of solvent mextures with a cricical point of miscibility / (1999)
Thesis (Ph. D.)--City University of New York, 1999.
Phase separation of solvent mixtures with a critical point of miscibility /--by Rajan Gupta. (1999)
Thesis (Ph. D.)--City University of New York, 1999. [Graduate Faculty in Engineering]
Wilson versus Clover fermions: A case for improvement (1998)
We present evidence for improvement with tadpole improved clover fermions based on an analysis of the chiral behavior of $B_K$ and the quark condensate. Also presented are a comparison of the mass...
Introduction to Lattice QCD (1998)
These notes aim to provide a pedagogical introduction to Lattice QCD. The topics covered include the scope of LQCD calculations, lattice discretization of gauge and fermion (naive, Wilson, and...
Testing the Chiral Behavior of the Hadron Spectrum (1998)
ource and sink (SS). We use five values of quark mass given by = 0:135 (C), 0:153 (S), 0:155 (U 1 ), 0:1558 (U 2 ), and 0:1563 (U 3 ), corresponding to pseudoscalar mesons of mass 2835, 983, 690, 545...
Status Report on Weak Matrix Element Calculations (1998)
Rajan Gupta, Tanmoy Bhattacharya
F27.37> 0:135 (C), 0:153 (S), 0:155 (U 1 ), 0:1558 (U 2 ), and 0:1563 (U 3 ). These quarks correspond to pseudoscalar mesons of mass 2835, 983, 690, 545 and 431 MeV respectively where we have used...
Prospects of Solving Grand Challenge Problems (1998)
Introduction The premise that millions of simple off-the-shelf computers working together can provide many-fold increase in computational power over conventional supercomputers and be more cost...
Quark Masses, B-parameters, and CP violation parameters $\epsilon$ and $\epsilon'/\epsilon$ (1998)
After a brief introduction to lattice QCD, I summarize the results for the light quark masses and the bag parameters $B_K$, $B_6^{1/2}$, and $B_8^{3/2}$. The implications of these results for the...
Advances in the Determination of Quark Masses (1997)
Bhattacharya, Tanmoy, Gupta, Rajan
Significant progress has been made in the determination of the light quark masses, using both lattice QCD and sum rule methods, in the last year. We discuss the different methods and review the...
B-parameters of 4-fermion operators from lattice QCD (1997)
This talk summarizes the status of the calculations of $B_K$, $B_7$, $B_8$, and $B_s$, done in collaboration with T. Bhattacharya, G. Kilcup, and S. Sharpe. Results for staggered, Wilson, and Clover...
Staggered fermion matrix elements using smeared operators (1997)
Kilcup, Greg, Gupta, Rajan, Sharpe, Stephen
We investigate the use of two kinds of staggered fermion operators, smeared and unsmeared. The smeared operators extend over a $4^4$ hypercube, and tend to have smaller perturbative corrections than...
Bhattacharya, Tanmoy, Gupta, Rajan, Maltman, Kim
We re-examine the use of sum rules in the extraction of light quark masses and discuss a number of potential problems with existing analyses. The most important issue is that of the overall...
Matrix Elements of 4-fermion Operators with Quenched Wilson Fermions (1996)
Gupta, Rajan, Bhattacharya, Tanmoy, Sharpe, Stephen
We presents results for the matrix elements of a variety of four-fermion operators calculated using quenched Wilson fermions. Our simulations are done on 170 lattices of size $32^3 x 64$ at $\beta =...
Light Quark Masses from Lattice QCD (1996)
Gupta, Rajan, Bhattacharya, Tanmoy
We present estimates of the masses of light quarks using lattice data. Our main results are based on a global analysis of all the published data for Wilson, Sheikholeslami-Wohlert (clover), and...
Comparison of Inversion Algorithms for Wilson Fermions on the CM5 (1996)
Gupta, Rajan, Bhattacharya, Tanmoy, Kilcup, Gregory
This talk presents results of a comparitive study of iterative algorithms like minimal residue ($MR$) and conjugate gradient ($CG$, $BiCG\gamma_5$, and \bicgstab) used for inverting the Dirac matrix...
Critical Exponents of the 3-D Ising Model (1996)
We present a status report on the ongoing analysis of the 3D Ising model with nearest-neighbor interactions using the Monte Carlo Renormalization Group (MCRG) and finite size scaling (FSS) methods on...
Hadron Spectrum with Wilson fermions (1995)
Bhattacharya, Tanmoy, Gupta, Rajan, Kilcup, Gregory, Sharpe, Stephen
We present results of a high statistics study of the quenched spectrum using Wilson fermions at $\beta=6.0$ on $32^3 \times 64$ lattices. We calculate the masses of mesons and baryons composed of...
Testing the chiral behavior of the hadron spectrum (1995)
Bhattacharya, Tanmoy, Gupta, Rajan, Sharpe, Stephen
We analyze the chiral behavior of the hadron spectrum obtained with quenched Wilson fermions on 170 $32^3 \times 64$ lattices at $\beta = 6.0$. We calculate masses of hadrons composed of both...
Status Report on Weak Matrix Element Calculations (1995)
Gupta, Rajan, Bhattacharya, Tanmoy
This talk presents results of weak matrix elements calculated from simulations done on 170 $32^3 \times 64$ lattices at $\beta = 6.0$ using quenched Wilson fermions. We discuss the extraction of...
Lattice analysis of semi-leptonic form factors (1995)
Bhattacharya, Tanmoy, Gupta, Rajan
We present preliminary results from simulations done on 170 $32^3 \times 64$ lattices at $\beta = 6.0$ using quenched Wilson fermions. This talk focuses on the $Q^2$ behavior of the form-factors,...
Decay constants with Wilson fermions at $\beta=6.0$ (1995)
Bhattacharya, Tanmoy, Gupta, Rajan
We present results of a high statistics study of $f_\pi$, $f_K$, $f_D$, $f_{D_s}$, and $f_V^{-1}$ in the quenched approximation using Wilson fermions at $\beta=6.0$ on $32^3 \times 64$ lattices. We...
Prospects of Solving Grand Challenge Problems (1995)
The recent woes of the supercomputer industry and changes in federal funding have caused some scientists to re-evaluate the means by which they hope to solve Grand Challenge problems. I evaluate the...
Phenomenology from 100 large lattices (1995)
Bhattacharya, Tanmoy, Gupta, Rajan
We present a status report on simulations being done on $32^3 \times 64$ lattices at $\beta = 6.0$ using quenched Wilson fermions. Phenomenologically relevant results for the spectrum, decay...
Topological Density and Instantons on a Lattice (1995)
We present an update on the study of topological structure of QCD. Issues addressed include a comparison between the plaquette and the geometric methods of calculating the topological density. We...
This talk contains an analysis of quenched chiral perturbation theory and its consequences. The chiral behavior of a number of quantities such as the pion mass $m_\pi^2$, the Bernard-Golterman ratios...
Semi-leptonic form-factors from lattice qcd (1994)
Bhattacharya, Tanmoy, Gupta, Rajan
We present results for semi-leptonic form-factors obtained on a statistical sample of $66$ $32^3 \times 64$ lattices at $\beta = 6.0$ using quenched Wilson fermions. We find $f_+^{D \to K l \nu}(q^2...
Matrix Elements of the Singlet Axial Current in the Proton (1994)
Gupta, Rajan, Mandula, Jeffrey
We present a method to estimate the matrix element of the singlet axial current within a polarized proton state using lattice QCD. The method relies on using the Adler-Bell-Jackiw anomaly and gives...
A pot-pourri of results in QCD from large lattice simulations on the CM5 (1993)
Bhattacharya, Tanmoy, Gupta, Rajan
We present a status report on simulations being done on $32^3 \times 64$ lattices at $\beta = 6.0$ using quenched Wilson fermions. Results for the spectrum, decay constants, the kaon B-parameter...
Geometric Measurement of Topological Susceptibility on Large Lattices (1993)
The topological susceptibility of the quenched QCD vacuum is measured on large lattices for three $\beta$ values from $6.0$ to $6.4$. Charges possibly induced by $O(a)$ dislocations are identified...
Semileptonic form factors of heavy-light mesons from lattice QCD (1993)
Gupta, Rajan, Bhattacharya, Tanmoy, Daniel, David
The form factors for the semileptonic decays of heavy-light pseudoscalar mesons of the type $D \to Ke\nu$ are studied in quenched lattice QCD at $\beta=6.0$ using Wilson fermions. We explore new...
Calculations of hadronic matrix elements using lattice qcd (1993)
I give a brief introduction to the scope of lattice QCD calculations in our effort to extract the fundamental parameters of the standard model. This goal is illustrated by two examples. First I...
Bethe-Salpeter Amplitudes and Density Correlations for Mesons with Wilson Fermions (1993)
Gupta, Rajan, Daniel, David, Grandy, Jeffrey
We present an investigation of various gauge invariant definitions of the $q\bar q$ Bethe-Salpeter (BS) amplitude for mesons in lattice QCD, and compare them to the Coulomb and Landau gauge BS...
$I=2$ pion scattering amplitude with Wilson fermions (1993)
Gupta, Rajan, Patel, Apoorva, Sharpe, Stephen
We present an exploratory calculation of the $I=2$ $\pi-\pi$ scattering amplitude at threshold using Wilson fermions in the quenched approximation, including all the required contractions. We find...
$I=2$ pion scattering amplitude with Wilson fermions (1993)
Gupta, Rajan, Patel, Apoorva, Sharpe, Stephen
We present an exploratory calculation of the $I=2$ $\pi-\pi$ scattering amplitude at threshold using Wilson fermions in the quenched approximation, including all the required contractions. We find...
$I=2$ pion scattering amplitude with Wilson fermions (1993)
Gupta, Rajan, Patel, Apoorva, Sharpe, Stephen
We present an exploratory calculation of the $I=2$ $\pi-\pi$ scattering amplitude at threshold using Wilson fermions in the quenched approximation, including all the required contractions. We find...
The Kaon $B$-parameter with Wilson Fermions (1992)
Gupta, Rajan, Daniel, David, Kilcup, Gregory W, Patel, Apoorva, Sharpe, Stephen R
We calculate the kaon $B$-parameter in quenched lattice QCD at $\beta=6.0$ using Wilson fermions at $\kappa=0.154$ and $0.155$. We use two kinds of non-local (``smeared'') sources for quark...
The Kaon $B$-parameter with Wilson Fermions (1992)
Gupta, Rajan, Daniel, David, Kilcup, Gregory W, Patel, Apoorva, Sharpe, Stephen R
We calculate the kaon $B$-parameter in quenched lattice QCD at $\beta=6.0$ using Wilson fermions at $\kappa=0.154$ and $0.155$. We use two kinds of non-local (``smeared'') sources for quark...
Thesis (Ph. D.)--Old Dominion University.
QCD with dynamical Wilson fermions (1989)
Gupta, Rajan, Patel, Apoorva, Baillie, Clive F., Guralnik, Gerald, Kilcup, Gregory W., Sharpe, Stephen R.
We present results from a study of QCD with two flavors of Wilson fermions using the hybrid Monte Carlo algorithm, which incorporates the effects of fermion loops exactly. We evaluate the performance...
Training in Trauma Surgery: Quantitative and Qualitative Aspects of a New Paradigm for Fellowship
Reilly, Patrick M., Schwab, C William, Haut, Elliott R., Gracias, Vicente H., Dabrowski, G Paul, Gupta, Rajan, ...
Methods of training fellows in trauma care vary widely. Little objective clinical data is available that validate current training models. We describe our experience with a model of clinical trauma...
Training in Trauma Surgery: Quantitative and Qualitative Aspects of a New Paradigm for Fellowship
Reilly, Patrick M., Schwab, C William, Haut, Elliott R., Gracias, Vicente H., Dabrowski, G Paul, Gupta, Rajan, ...
Methods of training fellows in trauma care vary widely. Little objective clinical data is available that validate current training models. We describe our experience with a model of clinical trauma...