308 Matching Results

Search Results

Advanced search parameters have been applied.

in subjects: "Lattice Field Theory"

open access

Quantum chromodynamics near the confinement limit

These nine lectures deal at an elementary level with the strong interaction between quarks and its implications for the structure of hadrons. Quarkonium systems are studied as a means for measuring the interquark interaction. This is presumably (part of) the answer a solution to QCD must yield, if it is indeed the correct theory of the strong interactions. Some elements of QCD are reviewed, and metaphors for QCD as a confining theory are introduced. The 1/N expansion is summarized as a way of g… more

Date: September 1, 1985

Creator: Quigg, C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Theoretical particle physics

My research in lattice gauge theory during the past year is described. Several projects were completed dealing with QCD simulations including dynamical fermions. Under the DOE Grand Challenge program, a large scale calculation of the QCD spectrum with two light flavors of dynamical staggered quarks was carried out. This calculation is one of the most significant efforts to data to take into account the effects of dynamical fermions. Smaller lattice spacing and lighter quark masses were used tha… more

Date: May 1, 1990

Creator: Gottlieb, S.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Elementary Particle Physics and High Energy Phenomena. Progress Report for FY93

Experimental and theoretical high-energy physics programs at the University of Colorado are reported. Areas of concentration include the following: study of the properties of the Z{sup 0} with the SLD detector; fixed-target K-decay experiments; the R&D program for the muon system: the SDC detector; high-energy photoproduction of states containing heavy quarks; electron--positron physics with the CLEO II detector at CESR; lattice QCD; and spin models and dynamically triangulated random surfaces.… more

Date: June 1, 1992

Creator: Barker, A. R.; Cumalat, J. P.; De Alwis, S. P.; DeGrand, T. A.; Ford, W. T.; Mahanthappa, K. T. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Group theory and lattice gauge fields

Lattice gauge theory, formulated in terms of invariant integrals over group elements on lattice bonds, benefits from many group theoretical notions. Gauge invariance provides an enormous symmetry and powerful constraints on expectation values. Strong coupling expansions require invariant integrals over polynomials in group elements, all of which can be evaluated by symmetry considerations. Numerical simulations involve random walks over the group. These walks automatically generate the invarian… more

Date: September 1, 1988

Creator: Creutz, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The Fermilab lattice supercomputer project

The ACPMAPS system is a highly cost effective, local memory MIMD computer targeted at algorithm development and production running for gauge theory on the lattice. The machine consists of a compound hypercube of crates, each of which is a full crossbar switch containing several processors. The processing nodes are single board array processors based on the Weitek XL chip set, each with a peak power of 20 MFLOPS and supported by 8 MBytes of data memory. The system currently being assembled has a… more

Date: February 1, 1989

Creator: Fischler, M.; Atac, R.; Cook, A.; Deppe, J.; Gaines, I.; Husby, D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Color force saturation in nuclear chromodynamics

A simple representation of the Q anti QQ anti Q Green's Function in the strong coupling quenched approximation to lattice QCD is used to illustrate the nature of color force saturation in chromodynamics. The example shows that configuration mixing allows a binding energy of a few MeV in a Q anti QQ anti Q ''molecule'' formed from mesons with mass 1 GeV. In lattice QCD, configuration mixing can be calculated on the same footing with glueball exchange effects by measuring the appropriate operator… more

Date: January 1, 1985

Creator: Sivers, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

ANL/Star project: a new architecture for large scale theoretical physics computations

The project reported consists of two phases, each of which has goals of substantial physics content on its own. In Phase 1, we have selected Star Technologies' ST-100 as the array processor for the prototype coupled system and have installed one on a Vax 11/750 host. Our goals with this system are to institute a substantial program in computational physics at Argonne based on the power provided by this system and thereby to gain experience with both the hardware and software architecture of the… more

Date: January 1, 1985

Creator: Rushton, A.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A streamlined method for chiral fermions on the lattice

We discussed the use of renormalization counterterms to restore the chiral gauge symmetry in a lattice theory of Wilson fermions. We show that a large class of counterterms can be implemented automatically by making a simple modification to the fermion determinant.

Date: November 10, 1992

Creator: Bodwin, G.T. (Argonne National Lab., IL (United States). High Energy Physics Div.) & Kovacs, E.V. (Fermi National Accelerator Lab., Batavia, IL (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Migdal approximation in Gribov field theory on a lattice

The asymptotic behavior of soft hadronic collisions is studied in the framework of Gribov's field theory for interacting pomerons. An analog model of Ising spins on a lattice with an anti-hermitian three-spin interaction is constructed. The structure of position space renormalization group analysis appropriate for this classical spin system is discussed, and the existence of a desired nontrivial fixed point is demonstrated in a Migdal approximation. In particular, it is found that the critical … more

Date: January 1, 1980

Creator: Tan, C.I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Reggeon Field Theory and the phases of QCD

We propose a Reggeon Field Theory phase diagram involving Sub-critical and Super-critical Pomeron behavior and the Expanding Disc. We describe the derivation of Reggeon Field Theory from QCD using infra-red analysis of the reggeon diagrams of the spontaneously broken theory. Matching the Reggeon Field Theory phase-diagram to that of lattice QCD with many fermions has significant implications for the chiral properties of continuum QCD when the number of flavors is less than the maximum allowed b… more

Date: July 21, 1987

Creator: White, A.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Hamiltonian lattice field theory: Computer calculations using variational methods

I develop a variational method for systematic numerical computation of physical quantities -- bound state energies and scattering amplitudes -- in quantum field theory. An infinite-volume, continuum theory is approximated by a theory on a finite spatial lattice, which is amenable to numerical computation. I present an algorithm for computing approximate energy eigenvalues and eigenstates in the lattice theory and for bounding the resulting errors. I also show how to select basis states and choo… more

Date: December 3, 1991

Creator: Zako, R.L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Nuclear physics at extreme energy density. Progress report, May 1991--April 1992

This report discusses topics in the following areas: QCD transport theory; minijets in hadronic and nuclear collisions; lattice gauge theory; hadronic matter and other studies; and strong electromagnetic fields. (LSP)

Date: May 15, 1992

Creator: Mueller, B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Potential energy for quarks

It is argued on theoretical and phenomenological grounds that confinement of quarks is intrinsically a many-body interaction. The Born-Oppenheimer approximation to the bag model is shown to give rise to a static potential energy that consists of a sum of two-body Coulomb terms and a many-body confining term. Following the success of this potential in heavy Q anti Q systems it is being applied to Q/sup 2/ anti Q/sup 2/. Preliminary calculations suggest that dimeson bound states with exotic flavo… more

Date: January 1, 1985

Creator: Heller, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Formation of a quark-gluon plasma in nuclear collisions

The spatial dependence of the energy deposition in the fragmentation regions is estimated for nuclear collisions at ISR energies, ..sqrt..s/A >approx. 30 GeV/nucleon. Two models (the trailing cascade and sequential decay scenarios) are contrasted. The results are compared to the quark-gluon plasma energy density computed via QCD lattice methods.

Date: June 1, 1982

Creator: Gyulassy, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Better potential for quarks

Date: January 1, 1985

Creator: Heller, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The ACPMAPS system: A detailed overview

This paper describes the ACPMAPS computing system -- its purpose, its hardware architecture, how the system is used, and relevant programming paradigms and concepts. Features of the hardware and software will be discussed in some detail, both quantitative and qualitative. This should give some perspective as to the suitability of the ACPMAPS system for various classes of applications, and as to where this system stands in the spectrum of today's supercomputers. The ACPMAPS project at Fermilab w… more

Date: January 1, 1992

Creator: Fischler, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Nonperturbative estimates of the Standard Model parameters

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project objectives were (1) to develop highly optimized codes for the simulation of lattice Quantum Chromodynamics (QCD) on the Connection Machine CM-5, (2) to use these codes to carry out a comprehensive analysis of Standard Model phenomenology using a large statistical sample, and (3) to combine the results of numerical simulations with experi… more

Date: August 1, 1997

Creator: Gupta, R.; Bhattacharya, T.; Tamayo, P.; Grandy, T.; Kilcup, G. & Sharpe, S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Staggered fermions and chiral symmetry breaking in transverse lattice regulated QED

Staggered fermions are constructed for the transverse lattice regularization scheme. The weak perturbation theory of transverse lattice non-compact QED is developed in light-cone gauge, and we argue that for fixed lattice spacing this theory is ultraviolet finite, order by order in perturbation theory. However, by calculating the anomalous scaling dimension of the link fields, we find that the interaction Hamiltonian becomes non-renormalizable for g{sup 2}(a) > 4{pi}, where g(a) is the bare (la… more

Date: July 1, 1992

Creator: Griffin, P. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Vortex operators in gauge field theories

Several related aspects of the 't Hooft vortex operator are studied. The current picture of the vacuum of quantum chromodynamics, the idea of dual field theories, and the idea of the vortex operator are reviewed first. The Abelian vortex operator written in terms of elementary fields and the calculation of its Green's functions are considered. A two-dimensional solvable model of a Dirac string is presented. The expression of the Green's functions more neatly in terms of Wu and Yang's geometrica… more

Date: July 1, 1980

Creator: Polchinski, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Lattice quark propagator in fixed gauges

A lattice study of the quenched QCD quark propagator in Landau and Coulomb gauges is reported. We find that m{sub D}{sup critical}, the value of the quark propagator pole in the chiral limit, is 290 {+-} 20 MeV ({beta} = 5.7) and 350 {+-} 40 MeV ({beta} = 6.0). Scaling and gauge dependence of this quantity are discussed. 7 refs., 3 figs., 3 tabs.

Date: January 1, 1989

Creator: Bernard, C.; Murphy, D.; Soni, A. & Yee, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Vacuum structure of pure gauge theories on the lattice

Results from simulations on two aspects of quark confinement in the pure gauge sector are presented. First is the calculation of the profile of the flux tube connecting a static q{bar q} pair in SU(2). By use of the Michael sum rules as a constraint, evidence is set forth that the energy density at the center of the flux tube goes to a constant as a function of quark- separation. Slow variation of the width and energy density is not ruled out. Secondly in the confined phase of lattice U(l), the… more

Date: October 1, 1992

Creator: Haymaker, R. W.; Singh, V.; Browne, D. & Wosiek, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Research in the theory of condensed matter and elementary particles. Progress report

Brief progress summaries are given on the dynamics of Polyakov's string, the problem of putting chiral fermions on the lattice, order and disorder that arises in two-dimensional systems with incommensurate phases, gauge theory in 1 + 1 dimension with quarks being treated as classical particles, the finite temperature deconfining transition in the 2 + 1 dimension compact U(1) lattice gauge theory (the Polyakov model), the Monte Carlo renormalization group treatment of the O(3) nonlinear sigma mo… more

Date: January 1, 1981

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Hadron mass estimates in the lattice gauge theory

Some estimates for the hadron masses in lattice QCD are presented in the approximation of neglecting dynamic fermion loops. Both light and heavy quark systems are considered and their dependence on the coupling constant and the quark mass is studied. Some results for the decay amplitudes are also given. We discuss how the eta prime mass can be computed to lowest order in n/sub f/, the number of dynamic fermion flavors.

Date: January 1, 1982

Creator: Hamber, H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Theoretical particle physics. Progress report, December 1, 1079-November 30, 1980. [Physics Dept. , Indiana Univ]

Work during the past year ranged from phenomenological studies of various quark systems to applications of quantum chromodynamics and lattice gauge theories. On the phenomenological side for mesons, studies of the charmonium and bottomonium families as well as the spectrum of states containing a single b-quark continued. As a result of some improved measurements, the topic of baryon magnetic moments was reconsidered. At the same time the properties of highly excited 3-quark systems were conside… more

Date: August 1, 1980

Creator: Hendry, A.W.; Lichtenberg, D.B. & Weingarten, D.H.

Item Type: Report

Partner: UNT Libraries Government Documents Department