2,621 Matching Results

Search Results

Advanced search parameters have been applied.

Duals for SU(N) SUSY Gauge Theories with an Antisymmetric Tensor: Five Easy Flavors

Description: I consider N = 1 supersymmetric SU(N{sub c}) gauge theories with matter fields consisting of one antisymmetric representation, five flavors, and enough antifundamental representations to cancel the gauge anomaly. Previous analyses are extended to the case of even N{sub c} with no superpotential. Using holomorphy I show that the theory has an interacting infrared fixed point for sufficiently large N{sub c}. These theories are interesting due to the fact that in going from five to four flavors the theory goes from a non-trivial infrared fixed point to confinement, in contradistinction to SUSY QCD, but in analogy to the behavior expected in non-SUSY QCD.
Date: December 16, 1997
Creator: Terning, John
Partner: UNT Libraries Government Documents Department

"Quantum Field Theory and QCD"

Description: This grant partially funded a meeting, "QFT & QCD: Past, Present and Future" held at Harvard University, Cambridge, MA on March 18-19, 2005. The participants ranged from senior scientists (including at least 9 Nobel Prize winners, and 1 Fields medalist) to graduate students and undergraduates. There were several hundred persons in attendance at each lecture. The lectures ranged from superlative reviews of past progress, lists of important, unsolved questions, to provocative hypotheses for future discovery. The project generated a great deal of interest on the internet, raising awareness and interest in the open questions of theoretical physics.
Date: February 25, 2006
Creator: Jaffe, Arthur M.
Partner: UNT Libraries Government Documents Department

National Computational Infrastructure for Lattice Gauge Theory

Description: In this document we describe work done under the SciDAC-1 Project National Computerational Infrastructure for Lattice Gauge Theory. The objective of this project was to construct the computational infrastructure needed to study quantim chromodynamics (QCD). Nearly all high energy and nuclear physicists in the United States working on the numerical study of QCD are involved in the project, as are Brookhaven National Laboratory (BNL), Fermi National Accelerator Laboratory (FNAL), and Thomas Jefferson National Accelerator Facility (JLab). A list of the serior participants is given in Appendix A.2. The project includes the development of community software for the effective use of the terascale computers, and the research and development of commodity clusters optimized for the study of QCD. The software developed as part of this effort is pubicly available, and is being widely used by physicists in the United States and abroad. The prototype clusters built with SciDAC-1 fund have been used to test the software, and are available to lattice guage theorists in the United States on a peer reviewed basis.
Date: May 30, 2008
Creator: Reed, Daniel, A
Partner: UNT Libraries Government Documents Department

Transverse Spin Physics: Recent Developments

Description: Transverse-spin physics has been very active and rapidly developing in the last few years. In this talk, I will briefly summarize recent theoretical developments, focusing on the associated QCD dynamics in transverse spin physics.
Date: December 10, 2008
Creator: Yuan, Feng
Partner: UNT Libraries Government Documents Department

Substructure of High-pT Jets at the LHC

Description: We study high-p{sub T} jets from QCD and from highly-boosted massive particles such as tops, W,Z and Higgs, and argue that infrared-safe observables can help reduce QCD backgrounds. Jets from QCD are characterized by different patterns of energy flow compared to the products of highly-boosted heavy particle decays, and we employ a variety of jet shapes, observables restricted to energy flow within a jet, to explore this difference. Results from Monte Carlo generators and arguments based on perturbation theory support the discriminating power of the shapes we refer to as planar flow and angularities. We emphasize that for massive jets, these and other observables can be analyzed perturbatively.
Date: July 2, 2008
Creator: Almeida, L.G.; Lee, S.J.; Perez, G.; Sterman, G.; Sung, I. & Virzi, J.
Partner: UNT Libraries Government Documents Department

Phases of QCD: Summary of the Rutgers Long Range Plan Town Meeting, January 12-14, 2007

Description: This White Paper summarizes the outcome of the Town Meeting on Phases of QCD that took place January 12-14, 2007 at Rutgers University, as part of the NSAC 2007 Long Range Planning process. The meeting was held in conjunction with the Town Meeting on Hadron Structure, including a full day of joint plenary sessions of the two meetings. Appendix A.1 contains the meeting agenda. This Executive Summary presents the prioritized recommendations that were determined at the meeting. Subsequent chapters present the essential background to the recommendations. While this White Paper is not a scholarly article and contains few references, it is intended to provide the non-expert reader
Date: May 14, 2007
Creator: Jacobs, Peter; Kharzeev, Dmitri; Muller, Berndt; Nagle, Jamie; Rajagopal, Krishna & Vigdor, Steve
Partner: UNT Libraries Government Documents Department

Recent Progress in Weakly-Coupled Heterotic String Phenomenology

Description: Some recent developments in the weakly-coupled heterotic string phenomenology are reviewed. We discuss several important issues such as dilaton/moduli stabilization, supersymmetry breaking (by hidden-sector gaugino condensation), gauge coupling unification (or the Newton's constant), the QCD axion, as well as cosmological problems involving the dilaton/moduli and the axion.
Date: July 28, 1997
Creator: Wu, Yi-Yen
Partner: UNT Libraries Government Documents Department

Resolving exceptional configurations

Description: In lattice QCD with Wilson fermions, exceptional configurations arise in the quenched approximation at small quark mass. The origin of these large previously uncontrolled lattice artifacts is identified. A simple well-defined procedure (MQA) is presented which removes the artifacts while preserving the correct continuum limit.
Date: October 1, 1997
Creator: Bardeen, W.; Eichten, E.; Duncan, A. & Thacker, H.
Partner: UNT Libraries Government Documents Department

Quark confinement and surface critical phenomena

Description: Surface critical phenomena and the related onset of Goldstone modes probe the fundamental properties of the confining flux in Quantum Chromodynamics. New ideas on surface roughening and their implications for lattice studies of quark confinement are presented. Problems with the oversimplified string description of the Wilson flux sheet are discussed.
Date: October 20, 1999
Creator: K.J. Juge, J. Kuti and C.J. Morningstar
Partner: UNT Libraries Government Documents Department

Quark confinement in a constituent quark model

Description: On the level of an effective quark theory, we define confinement by the absence of quark anti-quark thresholds in correlation function. We then propose a confining Nambu-Jona-Lasinio-type model. The confinement is implemented in analogy to Anderson localization in condensed matter systems. We study the model`s phase structure as well as its behavior under extreme conditions, i.e. high temperature and/or high density.
Date: July 1, 1995
Creator: Langfeld, K. & Rho, M.
Partner: UNT Libraries Government Documents Department

The gluon propagator in momentum space

Description: We consider quenched QCD on a 16{sup 3}{times}40 lattice at {beta}=6.0. We give preliminary numerical results for the lattice gluon propagator evaluated both in coordinate and momentum space. Our findings are compared with earlier results in the literature at zero momentum. In addition, by considering nonzero momenta we attempt to extract the form of the propagator and compare it to continuum predictions formulated by Gribov and others.
Date: December 31, 1992
Creator: Bernard, C.; Parrinello, C. & Soni, A.
Partner: UNT Libraries Government Documents Department

{pi}-{eta} mixing from QCD sum rules

Description: The q{sub 2} dependence of the {pi}-{eta} mixing amplitude is examined with the use of QCD sum rules. The linear slope of the mixing function {theta}(q{sup 2}) is found to be much smaller than that for {rho}-{omega} mixing. Thus the mixing amplitude is approximately the same in the space-like region as in the time-like one, and one may neglect the q{sup 2} dependence of the mixing. A comparison between a hadron-meson, an effective chiral model, and the QCD sum rules approaches is made.
Date: March 1, 1994
Creator: Chan, C. T.; Henley, E. M. & Meissner, T.
Partner: UNT Libraries Government Documents Department

Measurement of the Three-jet Mass Cross Section in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV

Description: This thesis describes the measurement of the inclusive three-jet cross section in proton-antiproton collisions at √s = 1.96 TeV measured at the D0 experiment at the Fermilab Tevatron Collider in the Fermi National Accelerator Laboratory, Batavia, Illinois, USA. The cross section as a function of three-jet invariant mass is provided in three regions of the third jet transverse momentum and three regions of jet rapidities. It utilizes a data sample collected in the so called Run IIa data taking period (2002-2006) corresponding to the integrated luminosity of about 0.7 fb<sup>-1</sup>. The results are used to test the next-to-leading order predictions of Quantum chromodynamics computed using the latest parton distribution functions.
Date: June 1, 2010
Creator: Hubacek, Zdenek
Partner: UNT Libraries Government Documents Department

A new moving frame to extract scattering phases in lattice QCD

Description: We present a derivation of the finite-size formulae in a moving frame with total momentum P=(2pi/L)(e_1+e_2). These formulae allow us to calculate the S-wave and P-wave scattering phases at more energies with a fixed lattice size and thus help us to determine the resonance parameters precisely.
Date: April 1, 2011
Creator: Dru Renner,Xu Feng,Karl Jansen
Partner: UNT Libraries Government Documents Department

Hadronic Correlations and Fluctuations

Description: We will provide a review of some of the physics which can be addressed by studying fluctuations and correlations in heavy ion collisions. We will discuss Lattice QCD results on fluctuations and correlations and will put them into context with observables which have been measured in heavy-ion collisions. Special attention will be given to the QCD critical point and the first order co-existence region, and we will discuss how the measurement of fluctuations and correlations can help in an experimental search for non-trivial structures in the QCD phase diagram.
Date: October 9, 2008
Creator: Koch, Volker
Partner: UNT Libraries Government Documents Department

Correlations and Fluctuations: Status and Perspectives

Description: We will provide an overview of the physics which can be addressed by studying fluctuations and correlations in heavy ion collisions. Observables, which have been discussed in the literature will be briefly reviewed and put in context with experiment and information from Lattice QCD. Special attention will be given to the QCD critical point and the first order co-existence region.
Date: April 15, 2008
Creator: Koch, Volker & Koch, Volker
Partner: UNT Libraries Government Documents Department

Bounds on Unparticles from the Higgs Sector

Description: We study supersymmetric QCD in the conformal window as a laboratory for unparticle physics, and analyze couplings between the unparticle sector and the Higgs sector. These couplings can lead to the unparticle sector being pushed away from its scale invariant fixed point. We show that this implies that low energy experiments will not be able to see unparticle physics, and the best hope of seeing unparticles is in high energy collider experiments such as the Tevatron and the LHC. We also demonstrate how the breaking of scale invariance could be observed at these experiments.
Date: May 20, 2007
Creator: Fox, Patrick J.; Rajaraman, Arvind & Shirman, Yuri
Partner: UNT Libraries Government Documents Department


Description: The authors identify a class of Euclidean configurations which appear to be dominant in the functional integral of the CP{sup N-1} models. These configurations are point-like topological excitations, and they may be viewed as constituents of instantons, although they are defined independently of instantons through a continuum duality transformation. They show not only that these configurations survive as N {yields} {infinity}, but that in the plasma phase they are responsible for the effects encountered within the 1/N expansion - confinement, {theta}-dependence, and dynamical mass generation. They also discuss the possible types of plasma phase for a statistical mechanical model of the interacting excitations. Possible generalization to QCD is briefly discussed.
Date: April 1, 1980
Creator: Bardakci, K.; Caldi, D.G. & Neuberger, H.
Partner: UNT Libraries Government Documents Department


Description: Here I review the temperature-dependence of heavy quarkonia correlators in potential models with three different screened potentials, and compare these to the results from lattice QCD. None of the potentials investigated yield results consistent with the lattice data, indicating that screening is likely not the mechanism for heavy quarkonia suppression. I also discuss a simple toy model, not based on temperature-dependent screening, that can reproduce the lattice results.
Date: March 11, 2006
Creator: MOCSY, A.
Partner: UNT Libraries Government Documents Department

Traveling waves and the renormalization group improvedBalitsky-Kovchegov equation

Description: I study the incorporation of renormalization group (RG)improved BFKL kernels in the Balitsky-Kovchegov (BK) equation whichdescribes parton saturation. The RG improvement takes into accountimportant parts of the next-to-leading and higher order logarithmiccorrections to the kernel. The traveling wave front method for analyzingthe BK equation is generalized to deal with RG-resummed kernels,restricting to the interesting case of fixed QCD coupling. The resultsshow that the higher order corrections suppress the rapid increase of thesaturation scale with increasing rapidity. I also perform a "diffusive"differential equation approximation, which illustrates that someimportant qualitative properties of the kernel change when including RGcorrections.
Date: December 1, 2006
Creator: Enberg, Rikard
Partner: UNT Libraries Government Documents Department

Adventures in Coulomb Gauge

Description: We study the phase structure of SU(2) gauge theories at zero and high temperature, with and without scalar matter fields, in terms of the symmetric/broken realization of the remnant gauge symmetry which exists after fixing to Coulomb gauge. The symmetric realization is associated with a linearly rising color Coulomb potential (which we compute numerically), and is a necessary but not sufficient condition for confinement.
Date: September 26, 2003
Creator: Greensite, J. & Olejnik, S.
Partner: UNT Libraries Government Documents Department