9,495 research outputs found
Supersymmetry versus black holes at the LHC
Supersymmetry and extra dimensions are the two most promising candidates for
new physics at the TeV scale. Supersymmetric particles or extra-dimensional
effects could soon be observed at the Large Hadron Collider. We propose a
simple but powerful method to discriminate the two models: the analysis of
isolated leptons with high transverse momentum. Black hole events are simulated
with the CATFISH black hole generator. Supersymmetry simulations use a
combination of PYTHIA and ISAJET, the latter providing the mass spectrum. Our
results show the measure of the dilepton invariant mass provides a strong
signature to differentiate supersymmetry and black hole events at the Large
Hadron Collider. Analysis of event-shape variables and multilepton events
complement and strengthen this conclusion.Comment: 12 pages, 5 figure
Effects due to a scalar coupling on the particle-antiparticle production in the Duffin-Kemmer-Petiau theory
The Duffin-Kemmer-Petiau formalism with vector and scalar potentials is used
to point out a few misconceptions diffused in the literature. It is explicitly
shown that the scalar coupling makes the DKP formalism not equivalent to the
Klein-Gordon formalism or to the Proca formalism, and that the spin-1 sector of
the DKP theory looks formally like the spin-0 sector. With proper boundary
conditions, scattering of massive bosons in an arbitrary mixed vector-scalar
square step potential is explored in a simple way and effects due to the scalar
coupling on the particle-antiparticle production and localization of bosons are
analyzed in some detail
Nonlinear Schrodinger equation with chaotic, random, and nonperiodic nonlinearity
In this paper we deal with a nonlinear Schr\"{o}dinger equation with chaotic,
random, and nonperiodic cubic nonlinearity. Our goal is to study the soliton
evolution, with the strength of the nonlinearity perturbed in the space and
time coordinates and to check its robustness under these conditions. Comparing
with a real system, the perturbation can be related to, e.g., impurities in
crystalline structures, or coupling to a thermal reservoir which, on the
average, enhances the nonlinearity. We also discuss the relevance of such
random perturbations to the dynamics of Bose-Einstein Condensates and their
collective excitations and transport.Comment: 4 pages, 6 figure
Decoherence induced by a phase-damping reservoir
A phase damping reservoir composed by -bosons coupled to a system of
interest through a cross-Kerr interaction is proposed and its effects on
quantum superpo sitions are investigated. By means of analytical calculations
we show that: i-) the reservoir induces a Gaussian decay of quantum coherences,
and ii-) the inher ent incommensurate character of the spectral distribution
yields irreversibility . A state-independent decoherence time and a master
equation are both derived an alytically. These results, which have been
extended for the thermodynamic limit, show that nondissipative decoherence can
be suitably contemplated within the EI D approach. Finally, it is shown that
the same mechanism yielding decoherence ar e also responsible for inducing
dynamical disentanglement.Comment: 8 pages, 3 figure
Black Hole Cross Section at the Large Hadron Collider
Black hole production at the Large Hadron Collider (LHC) was first discussed
in 1999. Since then, much work has been performed in predicting the black hole
cross section. In light of the start up of the LHC, it is now timely to review
the state of these calculations. We review the uncertainties in estimating the
black hole cross section in higher dimensions. One would like to make this
estimate as precise as possible since the predicted values, or lower limits,
obtain for the fundamental Planck scale and number of extra dimensions from
experiments will depend directly on the accuracy of the cross section. Based on
the current knowledge of the cross section, we give a range of lower limits on
the fundamental Planck scale that could be obtained at LHC energies.Comment: 28 pages, 9 figures, LaTeX; added references, corrected typos,
expanded discussio
Accuracy of a teleported trapped field state inside a single bimodal cavity
We propose a simplified scheme to teleport a superposition of coherent states
from one mode to another of the same bimodal lossy cavity. Based on current
experimental capabilities, we present a calculation of the fidelity that can be
achieved, demonstrating accurate teleportation if the mean photon number of
each mode is at most 1.5. Our scheme applies as well for teleportation of
coherent states from one mode of a cavity to another mode of a second cavity,
both cavities embedded in a common reservoir.Comment: 4 pages, 2 figures, in appreciation for publication in Physical
Review
Superradiant instabilities of rotating black branes and strings
Black branes and strings are generally unstable against a certain sector of
gravitational perturbations. This is known as the Gregory-Laflamme instability.
It has been recently argued that there exists another general instability
affecting many rotating extended black objects. This instability is in a sense
universal, in that it is triggered by any massless field, and not just
gravitational perturbations. Here we investigate this novel mechanism in
detail. For this instability to work, two ingredients are necessary: (i) an
ergo-region, which gives rise to superradiant amplification of waves, and (ii)
``bound'' states in the effective potential governing the evolution of the
particular mode under study. We show that the black brane Kerr_4 x R^p is
unstable against this mechanism, and we present numerical results for
instability timescales for this case. On the other hand, and quite
surprisingly, black branes of the form Kerr_d x R^p are all stable against this
mechanism for d>4. This is quite an unexpected result, and it stems from the
fact that there are no stable circular orbits in higher dimensional black hole
spacetimes, or in a wave picture, that there are no bound states in the
effective potential. We also show that it is quite easy to simulate this
instability in the laboratory with acoustic black branes.Comment: 19 pages, 10 figures. v2: Enlarged discussion on the necessary
conditions for the existence of instabilit
Gravitational quasinormal modes for Kerr Anti-de Sitter black holes
We investigate the quasinormal modes for gravitational perturbations of
rotating black holes in four dimensional Anti-de Sitter (AdS) spacetime. The
study of the quasinormal frequencies related to these modes is relevant to the
AdS/CFT correspondence. Although results have been obtained for Schwarzschild
and Reissner-Nordstrom AdS black holes, quasinormal frequencies of Kerr-AdS
black holes are computed for the first time. We solve the Teukolsky equations
in AdS spacetime, providing a second order and a Pade approximation for the
angular eigenvalues associated to the Teukolsky angular equation. The
transformation theory and the Regge-Wheeler-Zerilli equations for Kerr-AdS are
obtained.Comment: 20 pages, 13 figures, ReVTe
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