323 research outputs found
Statistical mechanics of Kerr-Newman dilaton black holes and the bootstrap condition
The Bekenstein-Hawking ``entropy'' of a Kerr-Newman dilaton black hole is
computed in a perturbative expansion in the charge-to-mass ratio. The most
probable configuration for a gas of such black holes is analyzed in the
microcanonical formalism and it is argued that it does not satisfy the
equipartition principle but a bootstrap condition. It is also suggested that
the present results are further support for an interpretation of black holes as
excitations of extended objects.Comment: RevTeX, 5 pages, 2 PS figures included (requires epsf), submitted to
Phys. Rev. Let
Counting reducible, powerful, and relatively irreducible multivariate polynomials over finite fields
We present counting methods for some special classes of multivariate
polynomials over a finite field, namely the reducible ones, the s-powerful ones
(divisible by the s-th power of a nonconstant polynomial), and the relatively
irreducible ones (irreducible but reducible over an extension field). One
approach employs generating functions, another one uses a combinatorial method.
They yield exact formulas and approximations with relative errors that
essentially decrease exponentially in the input size.Comment: to appear in SIAM Journal on Discrete Mathematic
On the Deconfinement Phase Transition in the Resonance Gas
We obtain the constraints on the ruling parameters of the dense hadronic gas
model at the critical temperature and propose the quasiuniversal ratios of the
thermodynamic quantities. The possible appearence of thermodynamical
instability in such a model is discussed.Comment: 7 pages, plain LaTeX, BI-TP 94/4
Valence Quark Spin Distribution Functions
The hyperfine interactions of the constituent quark model provide a natural
explanation for many nucleon properties, including the Delta-N splitting, the
charge radius of the neutron, and the observation that the proton's quark
distribution function ratio d(x)/u(x)->0 as x->1. The hyperfine-perturbed quark
model also makes predictions for the nucleon spin-dependent distribution
functions. Precision measurements of the resulting asymmetries A_1^p(x) and
A_1^n(x) in the valence region can test this model and thereby the hypothesis
that the valence quark spin distributions are "normal".Comment: 16 pages, 2 Postscript figure
Why is the B -> eta' X decay width so large ?
New mechanism for the observed inclusive B -> \eta'X decay is suggested. We
argue that the dominant contribution to this amplitude is due to the Cabbibo
favored b -> \bar{c}cs process followed by the transition \bar{c}c -> \eta'. A
large magnitude of the "intrinsic charm" component of \eta' is of critical
importance in our approach. Our results are consistent with an unexpectedly
large Br(B -> \eta'+X) \sim 10^{-3} recently announced by CLEO. We stress the
uniqueness of this channel for 0^{-+} gluonia search.Comment: Comments on a mixing model for intrinsic charm and pre-asymptotic
effects and some references are added. Latex, 9 page
How Fast Does Information Leak out from a Black Hole?
Hawking's radiance, even as computed without account of backreaction, departs
from blackbody form due to the mode dependence of the barrier penetration
factor. Thus the radiation is not the maximal entropy radiation for given
energy. By comparing estimates of the actual entropy emission rate with the
maximal entropy rate for the given power, and using standard ideas from
communication theory, we set an upper bound on the permitted information
outflow rate. This is several times the rates of black hole entropy decrease or
radiation entropy production. Thus, if subtle quantum effects not heretofore
accounted for code information in the radiance, the information that was
thought to be irreparably lost down the black hole may gradually leak back out
from the black hole environs over the full duration of the hole's evaporation.Comment: 8 pages, plain TeX, UCSBTH-93-0
An Alternative Method to Obtain the Quark Polarization of the Nucleon
An alternate method is described to extract the quark contribution to the
spin of the nucleon directly from the first moment of the deuteron structure
function, . It is obtained without recourse to the use of input on the
nucleon wave function from hyperon decays involving the flavor symmetry
parameters, F and D. The result for the quark polarization of the nucleon,
is in good agreement with the values of the singlet axial
current matrix element, , obtained from recent next-to-leading order
analyses of current proton, neutron and deuteron data.Comment: 7 pages, 1 figur
Statistical Mechanics of Black Holes
We analyze the statistical mechanics of a gas of neutral and charged black
holes. The microcanonical ensemble is the only possible approach to this
system, and the equilibrium configuration is the one for which most of the
energy is carried by a single black hole. Schwarzschild black holes are found
to obey the statistical bootstrap condition. In all cases, the microcanonical
temperature is identical to the Hawking temperature of the most massive black
hole in the gas. U(1) charges in general break the bootstrap property. The
problems of black hole decay and of quantum coherence are also addressed.Comment: 21 page
Black Hole Evaporation without Information Loss
An approach to black hole quantization is proposed wherein it is assumed that
quantum coherence is preserved. A consequence of this is that the Penrose
diagram describing gravitational collapse will show the same topological
structure as flat Minkowski space. After giving our motivations for such a
quantization procedure we formulate the background field approximation, in
which particles are divided into "hard" particles and "soft" particles. The
background space-time metric depends both on the in-states and on the
out-states. We present some model calculations and extensive discussions. In
particular, we show, in the context of a toy model, that the -matrix
describing soft particles in the hard particle background of a collapsing star
is unitary, nevertheless, the spectrum of particles is shown to be
approximately thermal. We also conclude that there is an important topological
constraint on functional integrals.Comment: 35 pages (including Figures); TEX, 3 figures in postscrip
Self Gravitating Fundamental Strings
We study the configuration of a typical highly excited string as one slowly
increases the string coupling. The dominant interactions are the long range
dilaton and gravitational attraction. In four spacetime dimensions, the string
slowly contracts from its initial (large) size until it approaches the string
scale where it forms a black hole. In higher dimensions, the string stays large
until the coupling reaches a critical value, and then it rapidly collapses to a
black hole. The implications for the recently proposed correspondence principle
are discussed.Comment: 20 pages, LaTe
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