15592421
Rigorous perimeter law upper bound on Wilson loops
Abstract We present a proof that in an arbitrary lattice gauge theory, the expectation value of a Wilson loop decays at least as fast as the exponential of the perimeter.
118398444
Boost invariant flow, black hole formation, and far-from-equilibrium dynamics in N = 4 supersymmetric Yang-Mills theory
Using gauge/gravity duality, we study the creation and evolution of boost-invariant anisotropic, strongly-coupled N=4 supersymmetric Yang-Mills plasma. In the dual gravitational description, this corresponds to horizon formation in a geometry driven to be anisotropic by a time-dependent change in boundary conditions.
15540326
Higher-order instanton effects
We present a formalism for calculating higher-order instanton effects based on a systematic expansion of the functional integrals about multiple instanton-anti-instanton configurations. We consider how various correlation functions may be constructed from the determinants and propagators in a background multiple-instanton field. A multiple-scattering formalism is then developed in order to express these determinants and propagators for a multi-instanton field in terms of the basic single-instanton quantities. The introduction of an improved gluon propagator based on a different choice of zero-mode constraints is required in order to justify the multiple-scattering formalism. As examples of this approach, we consider instanton interactions, which appear as corrections to the dilute-gas approximation for the instanton density, and the first-order quantum contributions to the static quark potential.
122912012
Canonical treatment of «noncanonical» gauges for constrained Hamiltonian systems
15374518
Can large N{sub c} equivalence between supersymmetric Yang-Mills theory and its orbifold projections be valid?
In previous work, we found that necessary and sufficient conditions for large N{sub c} equivalence between parent and daughter theories, for a wide class of orbifold projections of U(N{sub c}) gauge theories, are just the natural requirements that the discrete symmetry used to define the projection not be spontaneously broken in the parent theory, and the discrete symmetry permuting equivalent gauge group factors not be spontaneously broken in the daughter theory. In this paper, we discuss the application of this result to Z{sub k} projections of N=1 supersymmetric Yang-Mills theory in four dimensions, as well as various multiflavor generalizations. Z{sub k} projections with k>2 yielding chiral gauge theories violate the symmetry realization conditions needed for large N{sub c} equivalence, due to the spontaneous symmetry breaking of discrete chiral symmetry in the parent super-Yang-Mills theory. But for Z{sub 2} projections, we show that previous assertions of large N{sub c} inequivalence, in infinite volume, between the parent and daughter theories were based on incorrect mappings of vacuum energies, theta angles, or connected correlators between the two theories. With the correct identifications, there is no sign of any inconsistency. A subtle but essential feature of the connection between parent and daughter theories involvesmore » multivaluedness in the mapping of theta parameters from parent to daughter.« less
122668472
First Order Phase Transition in the SU(3) Gauge Theory at Finite Temperature
We argue that the phase transition which separates the low-temperature confining phase from the high-temperature nonconfining phase in the SU(3) gauge theory (without quarks) is first order.
121807340
EXCITATION FUNCTIONS AND NUCLEAR CHARGE DISPERSION IN THE FISSION OF URANIUM BY 0.1- TO 6.2-Gev PROTONS
Cross sections for formation of cesium and rubidium isotopes produced by bombardment of uranium with protons ranging in energy from 0.1 to 6.2 Bev were measured both radiochemically and mass spectrometrically. Independent yields were determined for Rb/sup 84/, Rb/sup 86/, Cs/sup 127/, Sc, su p 129/. Cs/sup 130/, Cs/sup 131/, Cs/sup 132/, Cs/sup 134/, Cs/sup 136/, and, at some e nergies, Rb/sup 83 and Cs/sup 135/. In addition, the independent yield of Ba/sup 131/ and the chain yields of Cs/sup 125/, Cs/sup 127/, Cs/sup 129/, La/sup 131/, Cs/sup 135/, Cs/sup 137/, ion cross sections of the Cs and Ba products on the neutron- excess side of stability decrease monotonically with increasing energy above 0.1 Bev, whereas the excitation functions for independent formation of the more neutron-deficient products in the Cs-Ba region and of Rb/sup 84/ and Rb/sup 86/ all go through maxima. The proton energies at which these maxima occur fall on a smooth curve when plotted against the neutronproton ratio of the product, with the peaks moving to higher energies with decreasing neutron-proton ratio. Under the assumption that the mass-yield curve in the region 125 < A < 140 is rather flat at each proton energy, the crosssection datamore » in the Cs region can be used to deduce the charge dispersion in this mass range. Plots of log sigma vs N/Z (or Z--Z/sub A/) show symmetrical bell-shaped peaks up to a bombarding energy of 0.38 Bev, with full width at halfmaximum increasing from 3.3 Z units at 0.10 Bev to about 5 Z units at 0.38 Bev, and with the peak position (Z/sub p/) moving from Z/ sub A/ -- 1.44 to Z/sub A/ -- 0.85 over the same energy range. At all higher energies, a double-peaked charge distribution was found, with a neutron-excess peak centered at N/Z approximates 1,515(Z/sub p/ approximates Z/sub A/ -- 1.9), and having approximately constant width and height at bombarding energies greater than 1 Bev. The peak on the neutron-deficient side which first becomes noticeable at 0.68 Bev appears to become broader and shift slightiy to smaller N/ Z values with increasing energy, The two peaks are of comparable height in the Bev region, and the peak-to-valley ratio is only approximates 2. The total formation cross section per mass number in the Cs region decreases from approximates 52 mb at 0.1 Bev to about 29 mb at 1 Bev and then stays approximately constant; the contribution of the neutron-excess peak above 1 Bev is about 12 mb. The neutron-excess peak corresponds in width and position to that obtained in fission by approximates 50-Mev protons. The recoil behavior of Ba/sup 140/ lends support to the idea that the neutron-excess products are formed in a lowdeposition-energy process. The recoil behavior of Ba/sup 131/ indicates that it is formed in a high-deposition-energy process. Post-fission neutron evaporation is required for the observed characteristics of the excitation functions of the rubidium isotopes and the neutron-deficient species in the Cs region. The correlation between neutron-proton ratios and positions of excitation function maxima is semiquantitatively accounted for if fission with unchanged charge distribution, followed by nucleon evaporation, is assumed. (auth)« less
122070464
Preparation of thin Films, Sources, and Targets
and targets are an obvious need in many applic a­ tions in nuclear physics and nuclear chemistry experiments. Publis hed in­ formation regarding the production and measurement of these materials is exceedingly sparse. The information. if given at all in the li terature, is usuaIJy ancillary to the "re sult s," and thus is given in such meager form that duplic a­ tion by other laboratories is difficult, if not well-nigh impossible. The most recent comprehensive article on the subject is that pub lished by Dodson et at. in the National Nuclear Energy Series, 1952, entitled Miscellaneous Physical and Chemical Techniques of the Los Alamos Series [referred to later as (58 )]. 2 Often the information exists as the "propert y" of a few exceedingly valuable individuals in various labor atories who prepare the materials but never publis h. The situat ion has impr oved somewhat since the appe arance of two journals devoted exclus ively to techniques, viz. Nuclear Instruments and Methods (North-Holland Publi shing Co.) and the Rus sian journal Pribory i Technika Eksperimenta (Instru ments and Experimental Tech­ niques) . The aim of this review article is to collate as much of this information as is possible. In this task the reviewer has been aided by peo ple too numerous to mention, and it is hoped that this assistance is reflected in the references. In addition, a literature search has been made, which, no matter how exhaus­ tively undertaken, must by its very nature be incomplete. It is hoped that this article will stimulate others int o rectifying these om issions by sending references and unpu blished information to the author for later publication.
120217954
( p , xn ) and ( p , pxn ) Reactions of Yttrium-89 with 5-85-MeV Protons