Search Results

Advanced search parameters have been applied.
open access

The axial anomaly and the dynamical breaking of chiral symmetry

Description: Using the quark triangle diagram for the Adler-Bell-Jackiw axial anomaly, we calculate the form factor for the {gamma}{sup *}{pi}{sup 0}{yields}{gamma} transition. This form factor depends on the quark mass, and we predict the right behavior with m{sub q}{approx_equal}250 MeV, the same quark mass generated by the dynamical breaking of chiral symmetry through a Nambu-Jona-Lasinio mechanism.
Date: October 1, 1991
Creator: Gross, Franz; Ito, Hiroshi & Buck, Warren
Partner: UNT Libraries Government Documents Department
open access

Applications of chiral symmetry

Description: The author discusses several topics in the applications of chiral symmetry at nonzero temperature. First, where does the rho go? The answer: up. The restoration of chiral symmetry at a temperature T{sub {chi}} implies that the {rho} and a{sub 1} vector mesons are degenerate in mass. In a gauged linear sigma model the {rho} mass increases with temperature, m{sub {rho}}(T{sub {chi}}) > m{sub {rho}}(0). The author conjectures that at T{sub {chi}} the thermal {rho} - a{sub 1}, peak is relatively hi… more
Date: March 1, 1995
Creator: Pisarski, R.D.
Partner: UNT Libraries Government Documents Department
open access

First experiences with HMC for dynamical overlap fermions

Description: The authors describe an HMC algorithm for dynamical overlap fermions which makes use of their good chiral properties. They test the algorithm in the Schwinger model. Topological sectors are readily changed even in the massless case.
Date: December 1, 1999
Creator: Bode, Achim; Heller, Urs M.; Edwards, Robert G. & Narayanan, Rajamani
Partner: UNT Libraries Government Documents Department
open access

Weak matrix elements for CP violation.

Description: We present preliminary results of matrix elements of four fermion operators relevant to the determination of e and E ' / E using staggered fermions. To calculate the matrix elements relevant to CP violation in Kaon decays it is important to use a lattice formulation which preserves (some) chiral symmetry.
Date: 2001
Creator: Bhattacharya, Tanmoy; Christ, N.; Fleming, G. T.; Kilcup, Gregory; Gupta, Rajan; Lee, Weonjong et al.
Partner: UNT Libraries Government Documents Department
open access

FUN WITH DIRAC EIGENVALUES.

Description: It is popular to discuss low energy physics in lattice gauge theory ill terms of the small eigenvalues of the lattice Dirac operator. I play with some ensuing pitfalls in the interpretation of these eigenvalue spectra. In short, thinking about the eigenvalues of the Dirac operator in the presence of gauge fields can give some insight, for example the elegant Banks-Casher picture for chiral symmetry breaking. Nevertheless, care is necessary because the problem is highly non-linear. This manifest… more
Date: January 26, 2006
Creator: CREUTZ, M.
Partner: UNT Libraries Government Documents Department
open access

QCD with chiral 4-fermion interactions ({chi}QCD)

Description: Lattice QCD with staggered quarks is augmented by the addition of a chiral 4-fermion interaction. The Dirac operator is now non-singular at m{sub q}=0, decreasing the computing requirements for light quark simulations by at least an order of magnitude. We present preliminary results from simulations at finite and zero temperatures for m{sub q}=0, with and without gauge fields. Chiral QCD enables simulations at physical u and d quark masses with at least an order of magnitude saving in CPU time.… more
Date: October 1, 1996
Creator: Kogut, J. B. & Sinclair, D. K.
Partner: UNT Libraries Government Documents Department
open access

WHY ROOTING FAILS.

Description: I explore the origins of the unphysical predictions from rooted staggered fermion algorithms. Before rooting, the exact chiral symmetry of staggered fermions is a flavored symmetry among the four 'tastes.' The rooting procedure averages over tastes of different chiralities. This averaging forbids the appearance of the correct 't Hooft vertex for the target theory.
Date: July 30, 2007
Creator: Creutz, M.
Partner: UNT Libraries Government Documents Department
open access

Finite-temperature corrections in the dilated chiral quark model

Description: We calculate the finite-temperature corrections in the dilated chiral quark model using the effective potential formalism. Assuming that the dilaton limit is applicable at some short length scale, we interpret the results to represent the behavior of hadrons in dense and hot matter. We obtain the scaling law, f{sub {pi}}(T)/f{sub {pi}} = m{sub Q}(T)/m{sub Q} {approx_equal} m{sub {sigma}}(T)/m{sub {sigma}}while we argue, using PCAC, that pion mass does not scale within the temperature range invo… more
Date: March 1, 1995
Creator: Kim, Y.; Lee, Hyun Kyu & Rho, M.
Partner: UNT Libraries Government Documents Department
open access

A lattice formulation of chiral gauge theories

Description: We present a method for implementing gauge theories of chiral fermions on the lattice. Discussed topics include: the lattice as a UV regulator, a chiral QED model, modification of the fermion determinant, large gauge-field momenta, and a non-perturbative problem.
Date: August 1, 1996
Creator: Bodwin, G. T.
Partner: UNT Libraries Government Documents Department
open access

Introduction to lattice QCD

Description: The goal of the lectures on lattice QCD (LQCD) is to provide an overview of both the technical issues and the progress made so far in obtaining phenomenologically useful numbers. The lectures consist of three parts. The author`s charter is to provide an introduction to LQCD and outline the scope of LQCD calculations. In the second set of lectures, Guido Martinelli will discuss the progress they have made so far in obtaining results, and their impact on Standard Model phenomenology. Finally, Mar… more
Date: December 1998
Creator: Gupta, R.
Partner: UNT Libraries Government Documents Department
open access

Strong WW scattering chiral lagrangians, unitarity and resonances

Description: Chiral lagrangians provide a model independent description of the strongly interacting symmetry breaking sector. In this work, first we review the LHC sensitivity to the chiral parameters (in the hardest case of non-resonant low-energy WW scattering). Later we show how to reproduce or predict the resonance spectrum by means of dispersion theory and the inverse amplitude method. We present a parameter space scan that covers many different strong WW scattering scenarios.
Date: August 1, 1996
Creator: Pelaez, J.R.
Partner: UNT Libraries Government Documents Department
open access

A search for disoriented chiral condensate at Fermilab

Description: A small test/experiment at the Fermilab Collider which measures charged particle and photon multiplicities in the forward direction, {eta} {approx} 4.1, has been carried out, with the primary goal being the search for disoriented chiral condensate (DCC). The author describes the experiment and analysis methods, together with preliminary results.
Date: October 1, 1996
Creator: Bjorken, J. D.
Partner: UNT Libraries Government Documents Department
open access

Thermal rho`s in the quark-gluon plasma

Description: I discuss different models which predict changes in the mass of the thermal {rho} field. I emphasize that while the predictions are strongly model dependent, nevertheless substantial shifts in the thermal {rho} mass are expected to occur at the point of phase transition. As long as the thermal {rho} peak does not become too broad, this should provide a striking signature of the existence of a phase transition.
Date: March 1, 1995
Creator: Pisarski, R.D.
Partner: UNT Libraries Government Documents Department
open access

Exact Chiral Symmetry for Domain Wall Fermions with Finite L{sub s}*

Description: We show how the standard domain wall action can be simply modified to allow arbitrarily exact chiral symmetry at finite fifth dimensional extent. We note that the method can be used for both quenched and dynamical calculations. We test the method using smooth and thermalized gauge field configurations. We also make comparisons of the performance (cost) of the domain wall operator for spectroscopy compared to other methods such as the overlap-Dirac operator and find both methods are comparable i… more
Date: October 1, 2000
Creator: Edwards, Robert G. & Heller, Urs M.
Partner: UNT Libraries Government Documents Department
open access

A lattice formulation of chiral gauge theories

Description: The authors present a method for formulating gauge theories of chiral fermions in lattice field theory. The method makes use of a Wilson mass to remove doublers. Gauge invariance is then restored by modifying the theory in two ways: the magnitude of the fermion determinant is replaced with the square root of the determinant for a fermion with vector-like couplings to the gauge field; a double limit is taken in which the lattice spacing associated with the fermion field is taken to zero before t… more
Date: December 1, 1995
Creator: Bodwin, G. T.
Partner: UNT Libraries Government Documents Department
open access

QCD scales and chiral symmetry in finite nuclei

Description: The authors report on this progress in the calculation of nuclear ground-state properties using effective Lagrangians whose construction is constrained by QCD scales and chiral symmetry. Good evidence is found that QCD and chiral symmetry apply to finite nuclei.
Date: October 1, 1997
Creator: Madland, D.G.
Partner: UNT Libraries Government Documents Department
open access

Isospin violation and the proton's neutral weak magnetic form factor

Description: The effects of isospin violation on the neutral weak magnetic form factor of the proton are studied using two-flavour chiral perturbation theory. The first nonzero contributions appear at O(p{sup 4}) in the small-momentum expansion, and the O(p{sup 5}) corrections are also calculated. The leading contributions from an explicit Delta(1232) isomultiplet are included as well. At such a high order in the chiral expansion, one might have expected a large number of unknown parameters to contribute. H… more
Date: October 1, 1998
Creator: Lewis, Randy & Mobed, Nader
Partner: UNT Libraries Government Documents Department
open access

Dyson-Schwinger equations: connecting small and large length-scales.

Description: The phenomenological application of Dyson-Schwinger equations to the calculation of meson properties observable at TJNAF is illustrated. Particular emphasis is given to the ability of this framework to unify long-range effects constrained by chiral symmetry with short-range effects prescribed by perturbation theory, and interpolate between them.
Date: February 8, 1999
Creator: Roberts, C.
Partner: UNT Libraries Government Documents Department
open access

Nuclear forces and chiral theories

Description: Recent successes in ab initio calculations of light nuclei (A=2-6) will be reviewed and correlated with the dynamical consequences of chiral symmetry. The tractability of nuclear physics evinced by these results is evidence for that symmetry. The relative importance of three-nucleon forces, four-nucleon forces, multi-pion exchanges, and relativistic corrections will be discussed in the context of effective field theories and dimensional power counting. Isospin violation in the nuclear force wil… more
Date: September 1, 1995
Creator: Friar, J.L.
Partner: UNT Libraries Government Documents Department
open access

On Yang--Mills Theories with Chiral Matter at Strong Coupling

Description: Strong coupling dynamics of Yang-Mills theories with chiral fermion content remained largely elusive despite much effort over the years. In this work, we propose a dynamical framework in which we can address non-perturbative properties of chiral, non-supersymmetric gauge theories, in particular, chiral quiver theories on S{sub 1} x R{sub 3}. Double-trace deformations are used to stabilize the center-symmetric vacuum. This allows one to smoothly connect smaller(S{sub 1}) to larger(S{sub 1}) phys… more
Date: August 20, 2008
Creator: Shifman, M.; /Minnesota U., Theor. Phys. Inst. /Saclay, SPhT; Unsal, Mithat & /SLAC /Stanford U., Phys. Dept.
Partner: UNT Libraries Government Documents Department
open access

Hunting the Scalar Glueball: Prospects for BES III

Description: The search for the ground state scalar glueball $G_0$ isreviewed. Spin zero glueballs will have unique dynamical properties ifthe $<G_0|\overline qq>$ amplitude is suppressed by chiralsymmetry, as it is to all orders in perturbation theory: for instance,mixing of $G_0$ with $\overline qq$ mesons would be suppressed, radiative$\jp$ decay would be a filter for new physics in the spin zero channel,and the decay $G_0 \rightarrow \overline KK$ could be enhanced relativeto $G_0 \rightarrow \pi \pi$. … more
Date: September 18, 2006
Creator: Chanowitz, Michael S.
Partner: UNT Libraries Government Documents Department
open access

Quantum chromodynamics and nuclear physics at extreme energy density. Progress report, May 15, 1993--May 14, 1994

Description: This report briefly discusses the following topics: quark-gluon plasma and high-energy collisions; hadron structure and chiral dynamics; nonperturbative studies and nonabelian gauge theories; and studies in quantum field theory.
Date: May 15, 1994
Creator: Mueller, B. & Springer, R.P.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen