164 research outputs found
Small Black Holes on Cylinders
We find the metric of small black holes on cylinders, i.e. neutral and static
black holes with a small mass in d-dimensional Minkowski-space times a circle.
The metric is found using an ansatz for black holes on cylinders proposed in
hep-th/0204047. We use the new metric to compute corrections to the
thermodynamics which is seen to deviate from that of the (d+1)-dimensional
Schwarzschild black hole. Moreover, we compute the leading correction to the
relative binding energy which is found to be non-zero. We discuss the
consequences of these results for the general understanding of black holes and
we connect the results to the phase structure of black holes and strings on
cylinders.Comment: 23 pages, 1 figure. v2: typos corrected, introduction expanded, v3:
presentation of sections 2 and 3 reordered and improved, explanatory remarks
added, refs adde
Baxter Q-operator and Separation of Variables for the open SL(2,R) spin chain
We construct the Baxter Q-operator and the representation of the Separated
Variables (SoV) for the homogeneous open SL(2,R) spin chain. Applying the
diagrammatical approach, we calculate Sklyanin's integration measure in the
separated variables and obtain the solution to the spectral problem for the
model in terms of the eigenvalues of the Q-operator. We show that the
transition kernel to the SoV representation is factorized into the product of
certain operators each depending on a single separated variable. As a
consequence, it has a universal pyramid-like form that has been already
observed for various quantum integrable models such as periodic Toda chain,
closed SL(2,R) and SL(2,C) spin chains.Comment: 29 pages, 9 figures, Latex styl
de Sitter thermodynamics and the braneworld
The de Sitter thermodynamics of cosmological models with a modified Friedmann
equation is considered, with particular reference to high-energy
Randall-Sundrum and Gauss-Bonnet braneworlds. The Friedmann equation can be
regarded as the first law of thermodynamics of an effective gravitational
theory in quasi de Sitter spacetime. The associated entropy provides some
selection rules for the range of the parameters of the models, and is proposed
for describing tunneling processes in the class of high-energy gravities under
consideration.Comment: 16 pages JHEP style, no figures. v2: references added; v3: typo
corrected in Eq.(3.1), supersedes published versio
Separation of variables for the quantum SL(2,R) spin chain
We construct representation of the Separated Variables (SoV) for the quantum
SL(2,R) Heisenberg closed spin chain and obtain the integral representation for
the eigenfunctions of the model. We calculate explicitly the Sklyanin measure
defining the scalar product in the SoV representation and demonstrate that the
language of Feynman diagrams is extremely useful in establishing various
properties of the model. The kernel of the unitary transformation to the SoV
representation is described by the same "pyramid diagram" as appeared before in
the SoV representation for the SL(2,C) spin magnet. We argue that this kernel
is given by the product of the Baxter Q-operators projected onto a special
reference state.Comment: 26 pages, Latex style, 9 figures. References corrected, minor
stylistic changes, version to be publishe
Caged Black Holes: Black Holes in Compactified Spacetimes I -- Theory
In backgrounds with compact dimensions there may exist several phases of
black objects including the black-hole and the black-string. The phase
transition between them raises puzzles and touches fundamental issues such as
topology change, uniqueness and Cosmic Censorship. No analytic solution is
known for the black hole, and moreover, one can expect approximate solutions
only for very small black holes, while the phase transition physics happens
when the black hole is large. Hence we turn to numerical solutions. Here some
theoretical background to the numerical analysis is given, while the results
will appear in a forthcoming paper. Goals for a numerical analysis are set. The
scalar charge and tension along the compact dimension are defined and used as
improved order parameters which put both the black hole and the black string at
finite values on the phase diagram. Predictions for small black holes are
presented. The differential and the integrated forms of the first law are
derived, and the latter (Smarr's formula) can be used to estimate the ``overall
numerical error''. Field asymptotics and expressions for physical quantities in
terms of the numerical ones are supplied. Techniques include ``method of
equivalent charges'', free energy, dimensional reduction, and analytic
perturbation for small black holes.Comment: 23 pages. v3: version to be published in PRD, 3 references adde
Order from disorder in lattice QCD at high density
We investigate the properties of the ground state of strong coupling lattice
QCD at finite density. Our starting point is the effective Hamiltonian for
color singlet objects, which looks at lowest order as an antiferromagnet, and
describes meson physics with a fixed baryon number background. We concentrate
on uniform baryon number backgrounds (with the same baryon number on all
sites), for which the ground state was extracted in an earlier work, and
calculate the dispersion relations of the excitations. Two types of Goldstone
boson emerge. The first, antiferromagnetic spin waves, obey a linear dispersion
relation. The others, ferromagnetic magnons, have energies that are quadratic
in their momentum. These energies emerge only when fluctuations around the
large-N_c ground state are taken into account, along the lines of ``order from
disorder'' in frustrated magnetic systems. Unlike other spectrum calculations
in order from disorder, we employ the Euclidean path integral. For comparison,
we also present a Hamiltonian calculation using a generalized
Holstein-Primakoff transformation. The latter can only be constructed for a
subset of the cases we consider.Comment: 24 pages, 6 figures, 1 tabl
Analysis of the vector and axialvector mesons with QCD sum rules
In this article, we study the vector and axialvector mesons with the
QCD sum rules, and make reasonable predictions for the masses and decay
constants, then calculate the leptonic decay widths. The present predictions
for the masses and decay constants can be confronted with the experimental data
in the future. We can also take the masses and decay constants as basic input
parameters and study other phenomenological quantities with the three-point
vacuum correlation functions via the QCD sum rules.Comment: 14 pages, 16 figure
Black Holes in Higher-Dimensional Gravity
These lectures review some of the recent progress in uncovering the phase
structure of black hole solutions in higher-dimensional vacuum Einstein
gravity. The two classes on which we focus are Kaluza-Klein black holes, i.e.
static solutions with an event horizon in asymptotically flat spaces with
compact directions, and stationary solutions with an event horizon in
asymptotically flat space. Highlights include the recently constructed
multi-black hole configurations on the cylinder and thin rotating black rings
in dimensions higher than five. The phase diagram that is emerging for each of
the two classes will be discussed, including an intriguing connection that
relates the phase structure of Kaluza-Klein black holes with that of
asymptotically flat rotating black holes.Comment: latex, 49 pages, 5 figures. Lectures to appear in the proceedings of
the Fourth Aegean Summer School, Mytiline, Lesvos, Greece, September 17-22,
200
Indirect Dark Matter Detection from Dwarf Satellites: Joint Expectations from Astrophysics and Supersymmetry
We present a general methodology for determining the gamma-ray flux from
annihilation of dark matter particles in Milky Way satellite galaxies, focusing
on two promising satellites as examples: Segue 1 and Draco. We use the
SuperBayeS code to explore the best-fitting regions of the Constrained Minimal
Supersymmetric Standard Model (CMSSM) parameter space, and an independent MCMC
analysis of the dark matter halo properties of the satellites using published
radial velocities. We present a formalism for determining the boost from halo
substructure in these galaxies and show that its value depends strongly on the
extrapolation of the concentration-mass (c(M)) relation for CDM subhalos down
to the minimum possible mass. We show that the preferred region for this
minimum halo mass within the CMSSM with neutralino dark matter is ~10^-9-10^-6
solar masses. For the boost model where the observed power-law c(M) relation is
extrapolated down to the minimum halo mass we find average boosts of about 20,
while the Bullock et al (2001) c(M) model results in boosts of order unity. We
estimate that for the power-law c(M) boost model and photon energies greater
than a GeV, the Fermi space-telescope has about 20% chance of detecting a dark
matter annihilation signal from Draco with signal-to-noise greater than 3 after
about 5 years of observation
Predicting beef carcass composition using tissue weights of a primal cut assessed by computed tomography
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