3,731 research outputs found
Conformal description of horizon's states
The existence of black hole horizon is considered as a boundary condition to
be imposed on the fluctuating metrics. The coordinate invariant form of the
condition for class of spherically symmetric metrics is formulated. The
diffeomorphisms preserving this condition act in (arbitrary small) vicinity of
the horizon and form the group of conformal transformations of two-dimensional
space ( sector of the total space-time). The corresponding algebra
recovered at the horizon is one copy of the Virasoro algebra. For general
relativity in dimensions we find an effective two-dimensional theory
governing the conformal dynamics at the horizon universally for any .
The corresponding Virasoro algebra has central charge proportional to the
Bekenstein-Hawking entropy. Identifying the zero-mode configuration we
calculate . The counting of states of this horizon's conformal field
theory by means of Cardy's formula is in complete agreement with the
Bekenstein-Hawking expression for the entropy of black hole in dimensions.Comment: 13 pages, latex, no figures; the final version to appear in Phys.
Lett.
UV divergence-free QFT on noncommutative plane
We formulate Noncommutative Qauntum Field Theory in terms of fields defined
as mean value over coherent states of the noncommutative plane. No *-product is
needed in this formulation and noncommutativity is carried by a modified
Fourier transform of fields. As a result the theory is UV finite and the cutoff
is provided by the noncommutative parameter theta.Comment: 6 pages, Latex, no figures. Accepted for publication in J.Phys.A. New
references adde
Single State Supermultiplet in 1+1 Dimensions
We consider multiplet shortening for BPS solitons in N=1 two-dimensional
models. Examples of the single-state multiplets were established previously in
N=1 Landau-Ginzburg models. The shortening comes at a price of loosing the
fermion parity due to boundary effects. This implies the disappearance
of the boson-fermion classification resulting in abnormal statistics. We
discuss an appropriate index that counts such short multiplets.
A broad class of hybrid models which extend the Landau-Ginzburg models to
include a nonflat metric on the target space is considered. Our index turns out
to be related to the index of the Dirac operator on the soliton reduced moduli
space (the moduli space is reduced by factoring out the translational modulus).
The index vanishes in most cases implying the absence of shortening. In
particular, it vanishes when there are only two critical points on the compact
target space and the reduced moduli space has nonvanishing dimension.
We also generalize the anomaly in the central charge to take into account the
target space metric.Comment: LaTex, 42 pages, no figures. Contribution to the Michael Marinov
Memorial Volume, ``Multiple facets of quantization and supersymmetry'' (eds.
M.Olshanetsky and A. Vainshtein, to be publish by World Scientific). The
paper is drastically revised compared to the first version. We add sections
treating the following issues: (i) a new index counting one-state
supermultiplets; (ii) analysis of hybrid models of general type; (iii)
generalization of the anomaly in the central charge accounting for the target
space metri
Defying jet-gas alignment in two radio galaxies at z~2 with extended light profiles: Similarities to brightest cluster galaxies
We report the detection of extended warm ionized gas in two powerful
high-redshift radio galaxies, NVSS J210626-314003 at z=2.10 and TXS 2353-003 at
z=1.49, that does not appear to be associated with the radio jets. This is
contrary to what would be expected from the alignment effect, a characteristic
feature of distant, powerful radio galaxies at z> 0.6. The gas also has smaller
velocity gradients and line widths than most other high-z radio galaxies with
similar data. Both galaxies are part of a systematic study of 50 high-redshift
radio galaxies with SINFONI, and are the only two that are characterized by the
presence of high surface-brightness gas not associated with the jet axis and by
the absence of such gas aligned with the jet. Both galaxies are spatially
resolved with ISAAC broadband imaging covering the rest-frame R band, and have
extended wings that cannot be attributed to line contamination. We argue that
the gas and stellar properties of these galaxies are more akin to gas-rich
brightest cluster galaxies in cool-core clusters than the general population of
high-redshift radio galaxies at z>2. In support of this interpretation, one of
our sources, TXS 2353-003, for which we have H\alpha\ narrowband imaging, is
associated with an overdensity of candidate H\alpha\ emitters by a factor of 8
relative to the field at z=1.5. We discuss possible scenarios of the
evolutionary state of these galaxies and the nature of their emission line gas
within the context of cyclical AGN feedback.Comment: A&A in pres
Solutions of the Klein-Gordon equation on manifolds with variable geometry including dimensional reduction
We develop the recent proposal to use dimensional reduction from the
four-dimensional space-time D=(1+3) to the variant with a smaller number of
space dimensions D=(1+d), d < 3, at sufficiently small distances to construct a
renormalizable quantum field theory. We study the Klein-Gordon equation on a
few toy examples ("educational toys") of a space-time with variable special
geometry, including a transition to a dimensional reduction. The examples
considered contain a combination of two regions with a simple geometry
(two-dimensional cylindrical surfaces with different radii) connected by a
transition region. The new technique of transforming the study of solutions of
the Klein-Gordon problem on a space with variable geometry into solution of a
one-dimensional stationary Schr\"odinger-type equation with potential generated
by this variation is useful. We draw the following conclusions: (1) The signal
related to the degree of freedom specific to the higher-dimensional part does
not penetrate into the smaller-dimensional part because of an inertial force
inevitably arising in the transition region (this is the centrifugal force in
our models). (2) The specific spectrum of scalar excitations resembles the
spectrum of the real particles; it reflects the geometry of the transition
region and represents its "fingerprints". (3) The parity violation due to the
asymmetric character of the construction of our models could be related to
violation of the CP symmetry.Comment: laTeX file, 9 pages, 8 figures. Significant corrections in the title,
abstract, text. Corrected formulas and figures. Added new references,
amendments in English. Acceptred for publication in Theoretical and
Mathematical Physics. To appear in vol. 167, may 201
Planckian space is an exact solution of the semiclassical Einstein equations
The product space configuration (with and being
radiuses of the components) carrying the electric charge is demonstrated to
be an exact solution of the semiclassical Einstein equations in presence of the
Maxwell field. If the logarithmic UV divergences are absent in the
four-dimensional theory the solution we find is identical to the classical
Bertotti-Robinson space () with no quantum corrections added. In
general, the analysis involves the quadratic curvature coupling
appearing in the effective action. The solutions we find are of the following
types: i) (for arbitrary ) charged configuration which is quantum
deformation of the Bertotti-Robinson space; ii) () Q=0
configuration with and being of the Planck order; iii)
() configuration ( and are of the Planck
order) not connected analytically to the Bertotti-Robinson space. The
interpretation of the solutions obtained and an indication on the internal
structure of the Schwarzschild black hole are discussed.Comment: 14 pages, latex, 1 figure; v2: a note on S2*S2 type solutions adde
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