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.
118596387
Holographic realization of large-Nc orbifold equivalence with non-zero chemical potential
A bstractRecently, it has been suggested that large-Nc orbifold equivalences may be applicable to certain theories with chemical potentials, including QCD, in certain portions of their phase diagram. When valid, such an equivalence offers the possibility of relating large-Nc QCD at non-zero baryon chemical potential, a theory with a complex fermion determinant, to a related theory whose fermion determinant is real and positive. In this paper, we provide a test of this large Nc equivalence using a holographic realization of a supersymmetric theory with baryon chemical potential and a related theory with isospin chemical potential. We show that the two strongly-coupled, large-Nc theories are equivalent in a large region of the phase diagram.
122912012
Canonical treatment of «noncanonical» gauges for constrained Hamiltonian systems
17198705
Necessary and sufficient conditions for non-perturbative equivalences of large Nc orbifold gauge theories
Large N coherent state methods are used to study the relation between U(Nc) gauge theories containing adjoint representation matter fields and their orbifold projections. The classical dynamical systems which reproduce the large Nc limits of the quantum dynamics in parent and daughter orbifold theories are compared. We demonstrate that the large Nc dynamics of the parent theory, restricted to the subspace invariant under the orbifold projection symmetry, and the large Nc dynamics of the daughter theory, restricted to the untwisted sector invariant under ``theory space'' permutations, coincide. This implies equality, in the large Nc limit, between appropriately identified connected correlation functions in parent and daughter theories, provided the orbifold projection symmetry is not spontaneously broken in the parent theory and the theory space permutation symmetry is not spontaneously broken in the daughter. The necessity of these symmetry realization conditions for the validity of the large Nc equivalence is unsurprising, but demonstrating the sufficiency of these conditions is new. This work extends an earlier proof of non-perturbative large Nc equivalence which was only valid in the phase of the (lattice regularized) theories continuously connected to large mass and strong coupling [1].
125172147
THE INSTABILITY OF HOT FLAT SPACE
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.
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
120315024
CROSS SECTIONS FOR THE PRODUCTION OF Cl, K, Ca, AND Sc ISOTOPES IN THE BOMBARDMENT OF Pb AND U WITH 3.0-Bev PROTONS
Cross sections for the formation of some nuclides in the mass number range 38 to 48 in the bombardment of Pb and U with 3.0-Bev protons were measured. The maximum of the isobaric yield distributions for the nuclides from the Pb bombardnnent occurs at the stability line, while that from U is somewhat on the neutron-excess side. Total cross sections of 4 to 5 mb per mass number are deduced from the Pb data leading to a revision of the mass-yield curve in this region as proposed by Wolfgang et al.The cross sections from uranium are approximately twice as large as those from Pb. The data are shown to be consistent with a cascade-fission-evaporation mechanism. (auth)
120217954
( p , xn ) and ( p , pxn ) Reactions of Yttrium-89 with 5-85-MeV Protons