2,753 research outputs found
Improved generating technique for D=5 supergravities and squashed Kaluza-Klein Black Holes
Recently we suggested a solution generating technique for five-dimensional
supergravity with three Abelian vector fields based on the hidden SO(4,4)
symmetry of the three-dimensionally reduced theory. This technique generalizes
the generating technique developed earlier for minimal 5D
supergravity (A. Bouchareb, G. Cl\'ement, C-M. Chen, D. V. Gal'tsov, N. G.
Scherbluk, and Th. Wolf, Phys. Rev. D {\bf 76}, 104032 (2007)) and provides a
new matrix representation for cosets forming the corresponding sigma-models in
both cases. Here we further improve these methods introducing a matrix-valued
dualisation procedure which helps to avoid difficulties associated with solving
the dualisation equations in the component form. This new approach is used to
generate a five-parametric rotating charged Kaluza-Klein black hole with the
squashed horizon adding one parameter more to the recent solution by Tomizawa,
Yasui and Morisawa which was constructed using the previous version of the
generating technique.Comment: 20 pages, revtex
Three-charge 2J black ring
Using recently proposed new solution generating technique, we construct the
charged version of Pomeranski-Senkov doubly rotating black ring in the
five-dimensional supergravity. For arbitrary values of charges the solution is
unbalanced, but the Dirac-Misner string is removed when two of the charges are
set to zero. In this particular case our solution can be uplifted to some
solution of six-dimensional vacuum gravity.Comment: 9 pages revtex
Extremal black holes in D=4 Gauss-Bonnet gravity
We show that four-dimensional Einstein-Maxwell-Dilaton-Gauss-Bonnet gravity
admits asymptotically flat black hole solutions with a degenerate event horizon
of the Reissner-Nordstr\"om type . Such black holes exist for
the dilaton coupling constant within the interval .
Black holes must be endowed with an electric charge and (possibly) with
magnetic charge (dyons) but they can not be purely magnetic. Purely electric
solutions are constructed numerically and the critical dilaton coupling is
determined . For each value of the dilaton
coupling within this interval and for a fixed value of the Gauss--Bonnet
coupling we have a family of black holes parameterized by their
electric charge. Relation between the mass, the electric charge and the dilaton
charge at both ends of the allowed interval of is reminiscent of the BPS
condition for dilaton black holes in the Einstein-Maxwell-Dilaton theory. The
entropy of the DGB extremal black holes is twice the Bekenstein-Hawking
entropy.Comment: New material and references added, errors corrected including higher
decimals in a_cr, figures improve
Counting free fermions on a line: a Fisher-Hartwig asymptotic expansion for the Toeplitz determinant in the double-scaling limit
We derive an asymptotic expansion for a Wiener-Hopf determinant arising in
the problem of counting one-dimensional free fermions on a line segment at zero
temperature. This expansion is an extension of the result in the theory of
Toeplitz and Wiener-Hopf determinants known as the generalized Fisher-Hartwig
conjecture. The coefficients of this expansion are conjectured to obey certain
periodicity relations, which renders the expansion explicitly periodic in the
"counting parameter". We present two methods to calculate these coefficients
and verify the periodicity relations order by order: the matrix Riemann-Hilbert
problem and the Painleve V equation. We show that the expansion coefficients
are polynomials in the counting parameter and list explicitly first several
coefficients.Comment: 11 pages, minor corrections, published versio
Characterizing correlations with full counting statistics: classical Ising and quantum XY spin chains
We propose to describe correlations in classical and quantum systems in terms
of full counting statistics of a suitably chosen discrete observable. The
method is illustrated with two exactly solvable examples: the classical
one-dimensional Ising model and the quantum spin-1/2 XY chain. For the
one-dimensional Ising model, our method results in a phase diagram with two
phases distinguishable by the long-distance behavior of the Jordan-Wigner
strings. For the quantum XY chain, the method reproduces the previously known
phase diagram.Comment: 6 pages, section on Lee-Yang zeros added, published versio
Dispersion representations and anomalous singularities of the triangle diagram
We discuss dispersion representations for the triangle diagram
, the single dispersion representation in and the
double dispersion representation in and , with special emphasis
on the appearance of the anomalous singularities and the anomalous cuts in
these representations. For the double dispersion representation in and
, the appearance of the anomalous cut in the region is
demonstrated, and a new derivation of the anomalous double spectral density is
given. We point out that the double spectral representation is particularly
suitable for applications in the region of and/or above the
two-particle thresholds. The dispersion representations for the triangle
diagram in the nonrelativistic limit are studied and compared with the triangle
diagram of the nonrelativistic field theory.Comment: 10 pages, revtex, added a reference, version to be published in Phys.
Rev.
FQHE interferometers in strong tunneling regime. The role of compactness of edge fields
We consider multiple-point tunneling in the interferometers formed between
edges of electron liquids with in general different filling factors in the
regime of the Fractional Quantum Hall effect (FQHE). We derive an effective
matrix Caldeira-Leggett models for the multiple tunneling contacts connected by
the chiral single-mode FQHE edges. It is shown that the compactness of the Wen-
Fr\"ohlich chiral boson fields describing the FQHE edge modes plays a crucial
role in eliminating the spurious non-locality of the electron transport
properties of the FQHE interferometers arising in the regime of strong
tunneling.Comment: 5 page
Global solutions for higher-dimensional stretched small black holes
Small black holes in heterotic string theory have vanishing horizon area at
the supergravity level, but the horizon is stretched to the finite radius
geometry once higher curvature corrections are turned
on. This has been demonstrated to give good agreement with microscopic entropy
counting. Previous considerations, however, were based on the classical local
solutions valid only in the vicinity of the event horizon. Here we address the
question of global existence of extremal black holes in the -dimensional
Einstein-Maxwell-Dilaton theory with the Gauss-Bonnet term introducing a
variable dilaton coupling as a parameter. We show that asymptotically flat
black holes exist only in a bounded region of the dilaton couplings where depends on . For (but not for ) the allowed range of includes the heterotic string values. For numerical solutions meet weak naked singularities at finite radii
(spherical cusps), where the scalar curvature diverges as
. For cusps are met in pairs, so that
solutions can be formally extended to asymptotically flat infinity choosing a
suitable integration variable. We show, however, that radial geodesics cannot
be continued through the cusp singularities, so such a continuation is
unphysical.Comment: 26 pages, 19 figures, minor correction
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