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The hybrid Monte Carlo Algorithm and the chiral transition

Description: In this talk the author describes tests of the Hybrid Monte Carlo Algorithm for QCD done in collaboration with Greg Kilcup and Stephen Sharpe. We find that the acceptance in the glubal Metropolis step for Staggered fermions can be tuned and kept large without having to make the step-size prohibitively small. We present results for the finite temperature transition on 4/sup 4/ and 4 x 6/sup 3/ lattices using this algorithm.
Date: January 1, 1987
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

Monte Carlo Renormalization Group: a review

Description: The logic and the methods of Monte Carlo Renormalization Group (MCRG) are reviewed. A status report of results for 4-dimensional lattice gauge theories derived using MCRG is presented. Existing methods for calculating the improved action are reviewed and evaluated. The Gupta-Cordery improved MCRG method is described and compared with the standard one. 71 refs., 8 figs.
Date: January 1, 1985
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

Introduction to lattice gauge theory

Description: The lattice formulation of Quantum Field Theory (QFT) can be exploited in many ways. We can derive the lattice Feynman rules and carry out weak coupling perturbation expansions. The lattice then serves as a manifestly gauge invariant regularization scheme, albeit one that is more complicated than standard continuum schemes. Strong coupling expansions: these give us useful qualitative information, but unfortunately no hard numbers. The lattice theory is amenable to numerical simulations by which one calculates the long distance properties of a strongly interacting theory from first principles. The observables are measured as a function of the bare coupling g and a gauge invariant cut-off approx. = 1/..cap alpha.., where ..cap alpha.. is the lattice spacing. The continuum (physical) behavior is recovered in the limit ..cap alpha.. ..-->.. 0, at which point the lattice artifacts go to zero. This is the more powerful use of lattice formulation, so in these lectures the author focuses on setting up the theory for the purpose of numerical simulations to get hard numbers. The numerical techniques used in Lattice Gauge Theories have their roots in statistical mechanics, so it is important to develop an intuition for the interconnection between quantum mechanics and statistical mechanics. This will be the emphasis of the first lecture. In the second lecture, the author reviews the essential ingredients of formulating QCD on the lattice and discusses scaling and the continuum limit. In the last lecture the author summarizes the status of some of the main results. He also mentions the bottlenecks and possible directions for research. 88 refs.
Date: January 1, 1987
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

QCD on the connection machine

Description: In this talk I give a brief introduction to the standard model of particle interactions and illustrate why analytical methods fail to solve QCD. I then give some details of our implementation of the high performance QCD code on the CM2 and highlight the important lessons learned. The sustained speed of the code at the time of this conference is 5.2 Gigaflops (scaled to a full 64K machine). Since this is a conference dedicated to computing in the 21st century, I will tailor my expectations (somewhat idiosyncratic) of the physics objectives to reflect what we will be able to do in 10 years time, extrapolating from where we stand today. This work is being done under a joint LANL-TMC collaboration consisting of C. Baillie, R. Brickner, D. Daniel, G. Kilcup, L. Johnson, A. Patel. S. Sharpe and myself. 5 refs.
Date: January 1, 1990
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

QCD spectrum from the lattice

Description: Considerable progress has been made in the last year to derive the spectrum from QCD in the quenched approximation. I review the results for the proton to rho mass ratio and show that we are close to getting results to within 10%. I present new results for 0{sup ++} and 2{sup ++} glueballs. These results are qualitative since we do not address the question of mixing of glueballs with quark states. Finally, I give a status report on the full QCD calculations (2 flavors of dynamical Wilson fermions) being done on the Connection Machine 2. 12 refs., 3 figs.
Date: January 1, 1989
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

Status of B[sub K] from lattice QCD

Description: A brief review of lattice calculations of the bag parameter BK relevant for understanding indirect CP violation in the neutral kaon sector is given. A status report on current state-of-the-art calculations is presented as well as a discussion of the value of BK exported to phenomenologists. This review was presented at the CKM Unitarity Triangle Workshop held at CERN during Feburary 13-16, 2002.
Date: January 1, 2002
Creator: Gupta, R. (Rajan)
Partner: UNT Libraries Government Documents Department

Improved Monte Carlo Renormalization Group Method

Description: An extensive program to analyse critical systems using an Improved Monte Carlo Renormalization Group Method (IMCRG) being undertaken at LANL and Cornell is described. Here we first briefly review the method and then list some of the topics being investigated. 9 refs.
Date: January 1, 1985
Creator: Gupta, R.; Wilson, K.G. & Umrigar, C.
Partner: UNT Libraries Government Documents Department

Design for a high field combined function superferric magnet

Description: A combined function superferric magnet option has been investigated for the Relativistic Heavy Ion Collider (RHIC). The option requires the maximum value of the field in the magnet to be much higher than that achieved in any existing combined function accelerator magnet. A model is presented here in which a good field quality can be maintained up to 2T. It is done by carefully designing the yoke structure and positioning the coils in such a way that the iron poles tend to saturate evenly across the gap. A cold iron model might be necessary for this magnet. 4 refs., 2 figs., 1 tab.
Date: January 1, 1985
Creator: Gupta, R.C. & Morgan, G.H.
Partner: UNT Libraries Government Documents Department

Collarless, close-in, shaped iron aperture designs for the SSC (Superconducting Super Collider) dipole

Description: The nominal-design SSC (Superconducting Super Collider) dipole encloses the coil in an iron yoke having a circular aperture. The radial gap between the coil and the iron is about 15 mm to provide space for a strong annular collar around the coil, and also to reduce the effects of iron saturation on central field harmonics. The 15 mm gap also reduces the desirable dipole field contributed by the iron. The present paper gives a coil and aperture configuration in which the gap is reduced to 5 mm at the midplane, in which the aperture is shaped to reduce the unwanted effects of iron saturation. The transfer function is increased about 5% at 6.6 Tesla and the unwanted harmonics are within SSC tolerances at all field levels. These designs would require that the yoke and containment vessel absorb the stresses due to assembly and magnetic forces. A short magnet is being built with a close-in shaped iron aperture and existing coil geometry to assess the benefits of this concept. 7 refs., 3 figs., 6 tabs.
Date: January 1, 1989
Creator: Gupta, R.C. & Morgan, G.H.
Partner: UNT Libraries Government Documents Department

Wilson Versus Clover Fermions: A Case for Improvement

Description: The authors present evidence for improvement with tadpole improved clover fermions based on an analysis of the chiral behavior of B{sub K} and the quark condensate. Also presented are a comparison of the mass splittings in the baryon octet and decuplet, a calculation of c{sub A} using standard 2-point correlation functions, and the problem of zero modes of the Dirac operator.
Date: July 14, 1998
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

Estimating and adjusting field quality in superconducting accelerator magnets

Description: The experience with estimating and adjusting field quality in RHIC (Relativistic Heavy Ion Collider) and SSC (Superconducting Super Collider) magnets is discussed. An alternate approach which makes a better estimate for systematic and random values of harmonics is presented.
Date: December 31, 1995
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

Influence of Proton Irradiation on Angular Dependence of Second Generation (2G)HTS

Description: In the Facility for Rare Isotope Beams (FRIB) the quadrupoles in the fragment separator are exposed to very high radiation and heat loads. High Temperature Superconductors (HTS) are a good candidate for these magnets because they can be used at {approx}30-50 K and tolerate higher heat generation than Nb-Ti magnets. Radiation damage studies of HTS wires are crucial to ensure that they will survive in a high radiation environment. HTS wires from two vendors were studied. Samples of 2G HTS wires from SuperPower and American Superconductor (ASC) were irradiated with a 42 {mu}A, 142 MeV proton beam from the Brookhaven Linac Isotope Producer (BLIP). The angular dependence of the critical current was measured in magnetic fields at 77K.
Date: May 1, 2011
Creator: Shiroyanagi, Y.; Greene, G.; Gupta, R. & Sampson, W.
Partner: UNT Libraries Government Documents Department

Common Coil Magnet System for VLHC

Description: This paper introduces the common coil magnet system for the proposed very large hadron collider (VLHC). In this system, the high energy booster (HEB), the injector to VLHC, is integrated as the iron dominated low field aperture within the coldmass of the common coil magnet design introduced earlier. This 4-in-1 magnet concept for a 2-in-1 machine should provide a major cost reduction in building and operating VLHC. Moreover, the proposed design reduces the field quality problems associated with the large persistent currents in Nb{sub 3}Sn magnets. The paper also shows that the geometric field harmonics can be made small. In this preliminary magnetic design. the current dependence in harmonics is significant but not umnanageable.
Date: February 12, 1999
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

First Physics from HotQCD Collaboration

Description: The following pages show results from the first series of runs on BG/L using the unoptimized code from the MILC collaboration. The calculations were run with the AsqTad improved staggered fermion action and the RHMC algorithm on a 32{sup 3} x 8 lattice. The jobs were run mostly during October, 2006 on approximately 5% of the machine. The run consisted of approximately 1000 trajectories per beta value, spanning beta = 6.458 to 6.85, covering a temperature range of 140-210 MeV.
Date: November 6, 2006
Creator: Soltz, R; Gupta, R & Grandy, J
Partner: UNT Libraries Government Documents Department

LQCD Phase 1 Runs with P4RHMC

Description: These results represent the first set of runs of 10 {beta} values ranging from 2000-7000 trajectories with the p4rhmc code. This initial run sequence spanned roughly 2-weeks in late January and Early February, 2007. To manage the submission of dependent jobs: subSet.pl--submits a set of dependent jobs for a single run; rmSet.pl--removes a set of dependent jobs in reverse order of submission; and statSet.pl--runs pstat command and prints parsed output along with directory contents. The results of running the statSet.pl command are printed for three different times during the start up the next sequence of runs using the milc code.
Date: February 13, 2007
Creator: Soltz, R & Gupta, R
Partner: UNT Libraries Government Documents Department

Lattice QCD Thermodynamcis : P4 Action for new beta and MILC Nt=6

Description: These results are from the continuing Lattice Quantum Chromodynamics runs on BG/L. We show analyzed thermodynamics results for 6-10k trajectories ({beta} dependent), of the 32{sup 3}{chi}8 runs with the p4rhmc v2.0 QMP{_}MPI.X (semi-optimized p4 code using qmp over mpi). These jobs had a number of omitted trajectories, due to zero size and over-sized data files. For this interim report these errors were removed from the output to save space. The results also include the output of a new ''histogram.perl'' script, used to plot the gauge action < S{sub g} >= 10*(1- < plaq >)-(1- < rect >) for three values of {beta}=3.51, 3.54, 3.57. This output will be used to determine the new {beta} values that will be run to define the critical temperature. We also show a preliminary analysis on the first 5,000 trajectories of the 32{sup 3}{chi}6 runs for the milc code, using the new su3{_}rhmc{_}susc{_}eos.3g1f.qmp-bgl2 faster RHMC algorithm.
Date: May 7, 2007
Creator: Soltz, R; Vranas, P & Gupta, R
Partner: UNT Libraries Government Documents Department

Lattice QCD Thermodynamics : 10k analysis with 1k thermalziation and block size of 500.

Description: This is a re-analysis of the Lattice QCD Thermodynamics p4rhcm new beta analysis (UCRL-TR-230742) with approximately 10k trajectories per beta point, rerun with thermalization cut at 1000, and a block size of 500. Some diagnostic text has been omitted to reduce the number of pages.
Date: May 10, 2007
Creator: Soltz, R; Vranas, P & Gupta, R
Partner: UNT Libraries Government Documents Department

Lattice QCD Thermodynamics First 5000 Trajectories

Description: These results represent the first LQCD analysis for approximately 5000 trajectories with each of the p4rhmc and milc codes, with some of the lower temperature runs having fewer. Both runs were for lattice dimensions of 32{sup 3}x8. Some 32{sup 4} T=0 jobs were also run for p4rhmc. The p4 calculation was performed with v2.0 QMP{_}MPI.X (semi-optimized p4 code using qmp over mpi) and milc version of the su3 rhmc susc eos executable dated Mar 1, 2007 on ubgl in the /usr/gapps/hip/qcd/milc/bin subdirectory (svn revision 28). As with previous runs, calculations were performed along lines of constant physics, with the light quark masses 2-3 times their physics values and the strange quark mass set by m{sub ud} = 0.1m{sub s}. Job submissions were performed using a new subSet.pl job submission script that locates current jobs and submits additional jobs with the same beta value as pending. Note that after reaching a limit of about 35 jobs subsequent submissions are delayed and will not be submitted directly from that state. The job submission script was used to submit revised versions of the milc and p4rhmc csh scripts. Initial thermalized lattices for each code were also for milc (taken from the firstPhys runs), but the p4rhmc runs include thermalization. The only modifications for running on BG/L were to the directory names and the mT parameter which determines job durations (24 hrs on BG/L vs. 4 hrs on ubgl). All finite temperature jobs were submitted to the 512 node partitions, and all T=0 runs were submitted to 2048 node partitions. The set of runs was plagued by filesystem errors on lscratch1 and lscratcH{sub 2}. Many jobs had to be reset (deleting the most recent output file for milc and/or lattice for p4) and resubmitted. The analysis was performed with a new set of scripts ...
Date: March 15, 2007
Creator: Soltz, R & Gupta, R
Partner: UNT Libraries Government Documents Department

Tc with AsqTad and p4rhmc, July 20, 2007 Update

Description: We present the ongoing analysis of Lattice Quantum Chromodynamics runs on the LLNL BG/L supercomputer. This installment adds the density analysis of the p4rhmc for the first few thousand trajectories and the {psi} - bar{psi} history for hot and cold starts with two values of beta.
Date: July 18, 2007
Creator: Soltz, R.; Vranas, P. & Gupta, R.
Partner: UNT Libraries Government Documents Department

Tc with AsqTada and p4rhmc, July 23 update.

Description: We present the ongoing analysis of Lattice Quantum Chromodynamics runs on the LLNL BG/L supercomputer. This installment adds the density analysis of the p4rhmc for the first five thousand trajectories and the AsqTad action results for N{sub {tau}} = 6 results for ten thousand trajectories.
Date: July 25, 2007
Creator: Soltz, R.; Vranas, P. & Gupta, R.
Partner: UNT Libraries Government Documents Department

RACETRACK MAGNET DESIGNS AND TECHNOLOGIES.

Description: This paper presents a review of racetrack coil magnet designs and technologies for high field magnets that can be used in LHC upgrade. The designs presented here allow both ''Wind & React'' and ''React & Wind'' technologies as they are based on flat racetrack coils with large bend radii. Test results of the BNL 10.3 T ''React & Wind'' common coil magnet are also presented. A possible use of High Temperature Superconductors (HTS) in future high field accelerator magnets is examined.
Date: April 3, 2006
Creator: GUPTA, R.
Partner: UNT Libraries Government Documents Department

First LQCD Physics Runs with MILC and P4RHMC

Description: An initial series of physics LQCD runs were submitted to the BG/L science bank with the milc and p4rhmc. Both runs were for lattice dimensions of 32{sup 2} x 8. The p4 calculation was performed with v2.0 QMP{_}MPI.X (semioptomized p4 code using qmp over mpi) and milc v7.2, also using RHMC, but not specifically optimized for BlueGene. Calculations were performed along lines of constant physics, with the light quark masses 2-3 times their physics values and the strange quark mass set by m{sub ud} = 0.1m{sub s}. Job submissions was performed using the standard milc and p4 scripts provided on the ubgl cluster. Initial thermalized lattices for each code were also provided in this way. The only modifications for running on BG/L were to the directory names and the mT parameter which determines job durations (24 hrs on BG/L vs. 4 hrs on ubgl). The milc scripts were set to resubmit themselves 10 times, and the p4 scripts were submitted serially using the ''psub -d'' job dependency option. The runp4rhmc.tcsh could not be used to resubmit due to the 30m time limit imposed on interactive jobs. Most jobs were submitted to the smallest, 512 node partitions, but both codes could also run on the 1024 node partitions with a gain of only 30-50%. The majority of jobs ran without error. Stalled jobs were often indicative of a communication gap within a partition that LC was able to fix quickly. On some occasion a zero-length lattice file was deleted to allow jobs to restart successfully. Approximately 1000 trajectories were calculated for each beta value, see Table . The analysis was performed with the standard analysis scripts for each code, make{_}summary.pl for milc and analysis.tcsh for p4rhmc. All lattices, log files, and job submission scripts have been archived to permanent storage for ...
Date: January 18, 2007
Creator: Soltz, R & Gupta, R
Partner: UNT Libraries Government Documents Department

Behavior of the finite-sized, three-dimensional, Ising model near the critical point

Description: Recent work showing the validity of hyperscaling involved results for finite size systems very near the critical point. The authors study this problem in more detail, and give estimators related to the Binder cumulant ratio which seem to approach the critical temperature from above and below. Based on these results, they estimate that the renormalized coupling constant, computed for the temperature fixed at the critical temperature and then taking the large system-size limit, is about 4.9 {+-} 0.1, and give a likely lower bound for it of 4.5. These estimates are argued to suffice to show the validity of hyperscaling.
Date: May 1, 1996
Creator: Baker, G.A. Jr. & Gupta, R.
Partner: UNT Libraries Government Documents Department