1,807 research outputs found
Thermodynamics of Schwarzschild-(Anti-)de Sitter Black Holes with account of quantum corrections
We discuss the quantum corrections to thermodynamics (and geometry) of S(A)dS
BHs using large one-loop anomaly induced effective action for dilaton
coupled matter (scalars and spinors). It is found the temperature, mass and
entropy with account of quantum effects for multiply horizon SdS BH and SAdS BH
what also gives the corresponding expressions for their limits: Schwarzschild
and de Sitter spaces. In the last case one can talk about quantum correction to
entropy of expanding Universe.
The anomaly induced action under discussion corresponds to 4d formulation
(s-wave approximation, 4d quantum matter is minimal one) as well as 2d
formulation (complete effective action, 2d quantum matter is dilaton coupled
one). Hence, most of results are given for the same gravitational background
with interpretation as 4d quantum corrected BH or 2d quantum corrected
dilatonic BH. Quantum aspects of thermodynamics of 4d 't Hooft BH model are
also considered.Comment: LaTeX file, 28 pages, some misprints are correcte
Discovery of supersymmetry with degenerated mass spectrum
Discovery of supersymmetric (SUSY) particles at the Large Hadron
Collider(LHC) has been studied for the models where squarks and gluino are much
heavier than the lightest supersymetric particle (LSP). In this paper, we
investigate the SUSY discovery in the models with degenerated mass spectrum up
to m_LSP~0.7 m_sq. Such mass spectrum is predicted in certain parameter region
of the mixed modulas anomaly mediation (MMAM) model. We find that the effective
transverse mass of the signal for the degenerated parameters shows the
distribution similar to that of the background. Experimental sensitivity of the
SUSY particles at the LHC therefore depends on the uncertainty of the
background in this class of model. We also find that SUSY signal shows an
interesting correlation between M_eff and ETmiss which may be used to determine
the signal region properly to enhance the S/N ratio even if the sparticle
masses are rather degenerated. The structure is universal for the models with
new heavy colored particles decaying into visible particles and a stable
neutral particle, dark matter.Comment: 18 pages, 7 figure, revtex
Inhomogeneous Equation of State of the Universe: Phantom Era, Future Singularity and Crossing the Phantom Barrier
The dark energy universe equation of state (EOS) with inhomogeneous,Hubble
parameter dependent term is considered. The motivation to introduce such a term
comes from time-dependent viscosity considerations and modifications of general
relativity. For several explicit examples of such EOS it is demonstrated how
the type of future singularity changes, how the phantom epoch emerges and how
crossing of phantom barrier occurs. Similar cosmological regimes are considered
for the universe with two interacting fluids and for universe with implicit
EOS. For instance, the crossing of phantom barrier is realized in easier way,
thanks to the presence of inhomogeneous term. The thermodynamical dark energy
model is presented where the universe entropy may be positive even at phantom
era as a result of crossing of w=-1 barrier.Comment: LaTeX, 13 pages, refs. added, version to appear in PR
String versus Einstein frame in an AdS/CFT induced quantum dilatonic brane-world universe
AdS/CFT induced quantum dilatonic brane-world where 4d boundary is flat or de
Sitter (inflationary) or Anti-de Sitter brane is considered. The classical
brane tension is fixed but boundary QFT produces the effective brane tension
via the account of corresponding conformal anomaly induced effective action.
This results in inducing of brane-worlds in accordance with AdS/CFT set-up as
warped compactification. The explicit, independent construction of quantum
induced dilatonic brane-worlds in two frames: string and Einstein one is done.
It is demonstrated their complete equivalency for all quantum cosmological
brane-worlds under discussion, including several examples of classical
brane-world black holes. This is different from quantum corrected 4d dilatonic
gravity where de Sitter solution exists in Einstein but not in Jordan (string)
frame. The role of quantum corrections on massive graviton perturbations around
Anti-de Sitter brane is briefly discussed.Comment: LaTeX file, 24 pages, minor changes to match with published versio
Black hole solutions in F(R) gravity with conformal anomaly
In this paper, we consider theory instead of Einstein gravity
with conformal anomaly and look for its analytical solutions. Depending on the
free parameters, one may obtain both uncharged and charged solutions for some
classes of models. Calculation of Kretschmann scalar shows that there is
a singularity located at , which the geometry of uncharged (charged)
solution is corresponding to the Schwarzschild (Reissner-Nordstr\"om)
singularity. Further, we discuss the viability of our models in details. We
show that these models can be stable depending on their parameters and in
different epoches of the universe.Comment: 12 pages, one figur
Phantom phase power-law solution in gravity
Power-law solutions for gravity coupled with perfect fluid have been
studied for spatially flat universe. It is shown that despite the matter
dominated and accelerating power-law solutions, the power-law solution exists
for an special form of when this universe enters a Phantom phase.Comment: 10 pages, Published online in Astrophysics and Space Scienc
Universal features of the holographic duality: conformal anomaly and brane gravity trapping from 5d AdS Black Hole
We calculate the holographic conformal anomaly and brane Newton potential
when bulk is 5d AdS BH. It is shown that such anomaly is the same as in the
case of pure AdS or (asymptotically) dS bulk spaces, i.e. it is (bulk) metric
independent one. While Newton potential on the static brane in AdS BH is
different from the one in pure AdS space, the gravity trapping still occurs for
two branes system. This indicates to metric independence of gravity
localization.Comment: LaTeX file, 14 page
Using Subsystem MT2 for Complete Mass Determinations in Decay Chains with Missing Energy at Hadron Colliders
We propose to use the MT2 concept to measure the masses of all particles in
SUSY-like events with two unobservable, identical particles. To this end we
generalize the usual notion of MT2 and define a new MT2(n,p,c) variable, which
can be applied to various subsystem topologies, as well as the full event
topology. We derive analytic formulas for its endpoint MT2{max}(n,p,c) as a
function of the unknown test mass Mc of the final particle in the subchain and
the transverse momentum pT due to radiation from the initial state. We show
that the endpoint functions MT2{max}(n,p,c)(Mc,pT) may exhibit three different
types of kinks and discuss the origin of each type. We prove that the subsystem
MT2(n,p,c) variables by themselves already yield a sufficient number of
measurements for a complete determination of the mass spectrum (including the
overall mass scale). As an illustration, we consider the simple case of a decay
chain with up to three heavy particles, X2 -> X1 -> X0, which is rather
problematic for all other mass measurement methods. We propose three different
MT2-based methods, each of which allows a complete determination of the masses
of particles X0, X1 and X2. The first method only uses MT2(n,p,c) endpoint
measurements at a single fixed value of the test mass Mc. In the second method
the unknown mass spectrum is fitted to one or more endpoint functions
MT2{max}(n,p,c)(Mc,pT) exhibiting a kink. The third method is hybrid, combining
MT2 endpoints with measurements of kinematic edges in invariant mass
distributions. As a practical application of our methods, we show that the
dilepton W+W- and tt-bar samples at the Tevatron can be used for an independent
determination of the masses of the top quark, the W boson and the neutrino,
without any prior assumptions.Comment: 47 pages, 9 figures. revised version, published in JHEP. Major
addition: a new appendix with the complete set of formulas for the MT2
endpoints as functions of the upstream transverse momentum pT and test mass
M
Unifying inflation with dark energy in modified F(R) Horava-Lifshitz gravity
We study FRW cosmology for a non-linear modified F(R) Horava-Lifshitz gravity
which has a viable convenient counterpart. A unified description of early-time
inflation and late-time acceleration is possible in this theory, but the
cosmological dynamic details are generically different from the ones of the
convenient viable F(R) model. Remarkably, for some specific choice of
parameters they do coincide. The emergence of finite-time future singularities
is investigated in detail. It is shown that these singularities can be cured by
adding an extra, higher-derivative term, which turns out to be qualitatively
different when compared with the corresponding one of the convenient F(R)
theory.Comment: LaTeX 12 pages, typos are correcte
Cosmological anti-deSitter space-times and time-dependent AdS/CFT correspondence
We study classes of five-dimensional cosmological solutions with negative
curvature, which are obtained from static solutions by an exchange of a spatial
and temporal coordinate, and in some cases by an analytic continuation. Such
solutions provide a suitable laboratory to address the time-dependent AdS/CFT
correspondence. For a specific example we address in detail the calculation of
the boundary stress-energy and the Wilson line and find disagreement with the
standard AdS/CFT correspondence. We trace these discrepancies to the
time-dependent effects, such as particle creation, which we further study for
specific backgrounds. We also identify specific time-dependent backgrounds that
reproduce the correct conformal anomaly. For such backgrounds the calculation
of the Wilson line in the adiabatic approximation indicates only a Coulomb
repulsion.Comment: LaTeX file, 47 pages, discussion is extended, version to appear in
PR
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