902 research outputs found
Pade-related resummations of the pressure of quark-gluon plasma by approximate inclusion of g**6-terms
We perform various resummations of the hot QCD pressure based on the actual
knowledge of the perturbation series which includes the g**6 ln(1/g) and part
of the g**6 terms. Resummations are performed separately for the short- and
long-distance parts. The g**6 term of the short-distance pressure is estimated
on the basis on the known UV cutoff dependence of the long-distance part. The
resummations are of the Pade and Borel-Pade type, using in addition the
(Pade-)resummed expression for the squared screening mass mE**2 and for the
EQCD coupling parameter gE**2. The resummed results depend weakly on the yet
unknown g**6 terms and on the the short-range renormalization scale, at all
temperatures. The dependence on the long-range renormalization scale is
appreciable at low temperatures T < 1 GeV. The resulting dependence of pressure
on temperature T is compatible with the results of the lattice calculations at
low T.Comment: 25 pages, 15 double figures, 4 single figures, revtex4; thoroughly
extended analysis; more figures; conclusions more clearly formulated; new
references added; title slightly changed; accepted for publication in
Phys.Rev.
Conformal Symmetry of a Black Hole as a Scaling Limit: A Black Hole in an Asymptotically Conical Box
We show that the previously obtained subtracted geometry of four-dimensional
asymptotically flat multi-charged rotating black holes, whose massless wave
equation exhibit symmetry may be
obtained by a suitable scaling limit of certain asymptotically flat
multi-charged rotating black holes, which is reminiscent of near-extreme black
holes in the dilute gas approximation. The co-homogeneity-two geometry is
supported by a dilation field and two (electric) gauge-field strengths. We also
point out that these subtracted geometries can be obtained as a particular
Harrison transformation of the original black holes. Furthermore the subtracted
metrics are asymptotically conical (AC), like global monopoles, thus describing
"a black hole in an AC box". Finally we account for the the emergence of the
symmetry as a consequence of the
subtracted metrics being Kaluza-Klein type quotients of .
We demonstrate that similar properties hold for five-dimensional black holes.Comment: Sections 3 and 4 significantly augmente
Phenomenology of A Three-Family Standard-like String Model
We discuss the phenomenology of a three-family supersymmetric Standard-like
Model derived from the orientifold construction, in which the ordinary chiral
states are localized at the intersection of branes at angles. In addition to
the Standard Model group, there are two additional U(1)' symmetries, one of
which has family non-universal and therefore flavor changing couplings, and a
quasi-hidden non-abelian sector which becomes strongly coupled above the
electroweak scale. The perturbative spectrum contains a fourth family of exotic
(SU(2)- singlet) quarks and leptons, in which, however, the left-chiral states
have unphysical electric charges. It is argued that these decouple from the low
energy spectrum due to hidden sector charge confinement, and that anomaly
matching requires the physical left-chiral states to be composites. The model
has multiple Higgs doublets and additional exotic states. The moduli-dependent
predictions for the gauge couplings are discussed. The strong coupling agrees
with experiment for reasonable moduli, but the electroweak couplings are too
small.Comment: 22 pages, 4 figure
Black hole pairs and supergravity domain walls
We examine the pair creation of black holes in the presence of supergravity
domain walls with broken and unbroken supersymmetry. We show that black holes
will be nucleated in the presence of non- extreme, repulsive walls which break
the supersymmetry, but that as one allows the parameter measuring deviation
from extremality to approach zero the rate of creation will be suppressed. In
particular, we show that the probability for creation of black holes in the
presence of an extreme domain wall is identically zero, even though an extreme
vacuum domain wall still has repulsive gravitational energy. This is consistent
with the fact that the supersymmetric, extreme domain wall configurations are
BPS states and should be stable against quantum corrections. We discuss how
these walls arise in string theory, and speculate about what string theory
might tell us about such objects.Comment: 21 pages LaTeX, special style files (psfrag.sty, efsf_psfrag.sty,
a4local.sty, epsf.tex), minor revisions and amended reference
Brane-world Kaluza-Klein reductions and Branes on the Brane
We present a systematic study of a new type of consistent ``Brane-world
Kaluza-Klein Reduction,'' which describe fully non-linear deformations of
co-dimension one objects that arise as solutions of a large class of gauged
supergravity theories in diverse dimensions, and whose world-volume theories
are described by ungauged supergravities with one half of the original
supersymmetry. In addition, we provide oxidations of these Ansatze which are in
general related to sphere compactified higher dimensional string theory or
M-theory. Within each class we also provide explicit solutions of brane
configurations localised on the world-brane. We show that at the Cauchy horizon
(in the transverse dimension of the consistently Kaluza-Klein reduced
world-brane) there is a curvature singularity for any configuration with a
non-null Riemann curvature or a non-vanishing Ricci scalar that lives in the
world-brane. Since the massive Kaluza-Klein modes can be consistently
decoupled, they cannot participate in regulating these singularities.Comment: latex, 30 page
All the Four Dimensional Static, Spherically Symmetric Solutions of Abelian Kaluza-Klein Theory
We present the explicit form for all the four dimensional, static,
spherically symmetric solutions in -d Abelian Kaluza-Klein theory by
performing a subset of transformations corresponding to four
boosts on the Schwarzschild solution, supplemented by
transformations. The solutions are parameterized by the mass , Taub-Nut
charge , electric and magnetic
charges. Non-extreme black holes (with zero Taub-NUT charge) have either the
Reissner-Nordstr\" om or Schwarzschild global space-time. Supersymmetric
extreme black holes have a null or naked singularity, while non-supersymmetric
extreme ones have a global space-time of extreme Reissner-Nordstr\" om black
holes.Comment: 8 pages, uses RevTex, improved version to appear in Phys. Rev. Let
Three-Family Supersymmetric Standard-like Models from Intersecting Brane Worlds
We construct the first three family N=1 supersymmetric string model with
Standard Model gauge group SU(3)_C x SU(2)_L x U(1)_Y from an orientifold of
type IIA theory on T^6/(Z_2 x Z_2) and D6-branes intersecting at angles. In
addition to the minimal supersymmetric Standard Model particles, the model
contains right-handed neutrinos, a chiral (but anomaly-free) set of exotic
multiplets, and extra vector-like multiplets. We discuss some phenomenological
features of this model.Comment: 4 pages, minor typos correcte
Conformal Symmetry for Black Holes in Four Dimensions
We show that the asymptotic boundary conditions of general asymptotically
flat black holes in four dimensions can be modified such that a conformal
symmetry emerges. The black holes with the asymptotic geometry removed in this
manner satisfy the equations of motion of minimal supergravity in five
dimensions. We develop evidence that a two dimensional CFT dual of general
black holes in four dimensions account for their black hole entropy.Comment: 24 pages, minor correction
Towards the two-loop Lcc vertex in Landau gauge
We are interested in the structure of the Lcc vertex in the Yang-Mills
theory, where c is the ghost field and L the corresponding BRST auxiliary
field. This vertex can give us information on other vertices, and the possible
conformal structure of the theory should be reflected in the structure of this
vertex. There are five two-loop contributions to the Lcc vertex in the
Yang-Mills theory. We present here calculation of the first of the five
contributions. The calculation has been performed in the position space. One
main feature of the result is that it does not depend on any scale, ultraviolet
or infrared. The result is expressed in terms of logarithms and Davydychev
integral J(1,1,1) that are functions of the ratios of the intervals between
points of effective fields in the position space. To perform the calculation we
apply Gegenbauer polynomial technique and uniqueness method.Comment: 27 pp, 2 figures, Latex2e, revised version, to appear in IJMPA,
references added, comments on nonsupersymmetric case adde
Microstates of Four-Dimensional Rotating Black Holes from Near-Horizon Geometry
We show that a class of four-dimensional rotating black holes allow
five-dimensional embeddings as black rotating strings. Their near-horizon
geometry factorizes locally as a product of the three-dimensional anti-deSitter
space-time and a two-dimensional sphere (AdS_3 x S^2), with angular momentum
encoded in the global space-time structure. Following the observation that the
isometries on the AdS_3 space induce a two-dimensional (super)conformal field
theory on the boundary, we reproduce the microscopic entropy with the correct
dependence on the black hole angular momentum.Comment: 11 pages, revte
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