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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

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

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

Improved mesh generator for the POISSON Group Codes

Description: This paper describes the improved mesh generator of the POISSON Group Codes. These improvements enable one to have full control over the way the mesh is generated and in particular the way the mesh density is distributed throughout this model. A higher mesh density in certain regions coupled with a successively lower mesh density in others keeps the accuracy of the field computation high and the requirements on the computer time and computer memory low. The mesh is generated with the help of codes AUTOMESH and LATTICE; both have gone through a major upgrade. Modifications have also been made in the POISSON part of these codes. We shall present an example of a superconducting dipole magnet to explain how to use this code. The results of field computations are found to be reliable within a few parts in a hundred thousand even in such complex geometries.
Date: March 16, 1987
Creator: Gupta, R.C.
Partner: UNT Libraries Government Documents Department

More on the first order chiral symmetry transition in QCD

Description: We present evidence from numerical simulations for a first order chiral symmetry restoration transition in QCD at finite temperature. Also, for quarks in the fundamental representation, there is a simultaneous deconfinement transition. These transitions are present only for small quark masses. We use an exact algorithm to incorporate the dynamical quarks.
Date: September 1, 1986
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

Modifications in the AUTOMESH and other POISSON Group Codes

Description: Improvements in the POISSON Group Codes are discussed. These improvements allow one to compute magnetic field to an accuracy of a few parts in 100,000 in quite complicated geometries with a reduced requirement on computational time and computer memory. This can be accomplished mainly by making the mesh dense at some places and sparse at other places. AUTOMESH has been modified so that one can use variable mesh size conveniently and efficiently at a number of places. We will present an example to illustrate these techniques. Several other improvements in the codes AUTOMESH, LATTICE and POISSON will also be discussed.
Date: January 1, 1986
Creator: Gupta, R.C.
Partner: UNT Libraries Government Documents Department

Simulating QCD with dynamical Wilson and staggered fermions

Description: The author presents a summary of the work done during the last year by the Los Alamos lattice collaboration to study QCD with the Hybrid Monte Carlo Algorithm. The specific questions addressed are the finite temperature transition for both staggered and Wilson fermions and screening in the heavy q/bar q/ potential with Wilson fermions. The author also presents a discussion of the efficiency of the fermion update algorithm. 13 refs., 8 figs.
Date: January 1, 1988
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department

Food for thought: Five lectures on lattice gauge theory

Description: The topics covered in these lectures are the heavy anti qq potential, glueballs, the chiral transition with dynamical fermions, Weak interaction matrix elements on the lattice and Monte Carlo renormalization group. Even though for the most part these lectures are reviews, many new results and ideas are also presented. The emphasis is on critical analysis of existing data, exposing bottlenecks and a discussion of open problems. Five individual papers have been indexed separately.
Date: January 1, 1987
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

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

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

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

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

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