118446121
Mass function and particle creation in Schwarzschild–de Sitter spacetime
We construct a mass or energy function for the non-Nariai class Schwarzschild–de Sitter black hole spacetime in the region between the black hole and the cosmological event horizons. The mass function is local, positive definite, continuous and increases monotonically with the radial distance from the black hole event horizon. We derive the Smarr formula using this mass function, and demonstrate that the mass function reproduces the two-temperature Schwarzschild–de Sitter black hole thermodynamics, along with a term corresponding to the negative pressure due to positive cosmological constant. We further give a field theoretic derivation of the particle creation by both the horizons and discuss its connection with the mass function.
118575846
Massive spin-2 and spin-1/2 no hair theorems for stationary axisymmetric black holes
We present a proof of the no hair theorems corresponding to free massive non-perturbative PauliFierz spin-2 and perturbative massive spin- 1 fields for stationary axisymmetric de Sitter black hole spacetimes of dimension four with two commuting Killing vector fields. The applicability of these results for asymptotically flat and anti-de Sitter spacetimes are also discussed.
118336392
On the realizability of relativistic acoustic geometry under a generalized perturbation scheme for axisymmetric matter flow onto black holes
We propose a novel linear perturbation scheme to study the stability properties of the stationary transonic integral solutions for axisymmetric matter flow around astrophysical black holes for the Schwarzschild as well as for rotating Rindler space time. We discuss the emergence of the relativistic acoustic geometry as a consequence of such stability analysis. Our work thus makes a crucial connection between two apparently non-overlapping fields of research - the accretion astrophysics and the analogue gravity phenomena.
118213552
Acoustic geometry through perturbation of mass accretion rate : I - radial flow in general static spacetime
We propose a novel perturbation scheme to perform the linear stability analysis of stationary transonic integral accretion solutions corresponding to the hydrodynamic non self-gravitating radial flow of matter in a general static black hole spacetime. We demonstrate that a metric independent perturbation scheme can be developed, which leads to the emergence of the relativistic acoustic geometry and ensures the stability of the background stationary solutions. The acoustic metric obtained by perturbing the mass accretion rate rate is found to be identical with that obtained through the perturbation of the velocity potential. Our work thus makes a crucial connection between two apparently disjoint fields of study - accretion astrophysics and analogue gravity phenomena. We also formally prove that acoustic horizons never form in the Rindler spacetime.
118589509
A note on Hawking radiation via complex path analysis
As long as we neglect backreaction, the Hawking temperature of a given black hole would not depend upon the parameters of the particle species we are considering. In the semiclassical complex path analysis approach of Hawking radiation, this has been verified by taking scalar and Dirac spinors separately for different stationary spacetime metrics. Here we show in a coordinate-independent way that for an arbitrary spacetime with any number of dimensions, the equations of motion for a Dirac spinor, a vector, spin-2 and spin- fields reduce to Klein–Gordon equations in the WKB semiclassical limit. We then obtain, under some suitable assumptions, the complex solutions of those resulting scalar equations across the Killing horizon of a stationary spacetime to get a coordinate-independent expression for the emission probability identical for all particle species. Finally we consider some explicit examples to demonstrate the validity of that expression.
125083170
Acoustic geometry through perturbation of mass accretion rate - axisymmetric flow in static spacetimes
This is the second of our series of papers devoted to the study of the stability analysis of the stationary transonic integral solutions for accretion flow onto a static compact object, using the acoustic geometry. Precisely, we consider accretion of an axisymmetric, inviscid and irrotational fluid in a general static axisymmetric spacetime and study the perturbation of the mass accretion rate, and demonstrate the natural emergence of the general relativistic acoustic geometry. In other words, the astrophysical accretion process has a natural interpretation as an example of the acoustic analogue gravity phenomenon. We also discuss two explicit examples of the Schwarzschild and the Rindler spacetimes. For the later, in particular, we demonstrate that for smooth flow fileds there can be no sonic point.
15636466
Gaugino mass nonuniversality in an SO(10) supersymmetric grand unified theory: Low-energy spectra and collider signals
We derive the nonuniversal gaugino mass ratios in a supergravity (SUGRA) framework where the Higgs superfields belong to the nonsinglet representations 54 and 770 in an SO(10) grand unified theory (GUT). We evaluate the ratios for the phenomenologically viable intermediate breaking chain SU(4){sub C}xSU(2){sub L}xSU(2){sub R}(G{sub 422}). After a full calculation of the gaugino mass ratios, noting some errors in the earlier calculation for 54, we obtain, using the renormalization group equations, interesting low scale phenomenology of such breaking patterns. Here, we assume the breaking of the SO(10) GUT group to the intermediate gauge group and that to the standard model take place at the GUT scale itself. We also study the collider signatures in multilepton channels at the Large Hadron Collider (LHC) for some selected benchmark points allowed by the cold dark-matter relic density constraint provided by the WMAP data and compare these results with the minimal supergravity (mSUGRA) framework with similar gluino masses indicating their distinguishability in this regard.
119189999
Signatures of supersymmetry with non-universal Higgs mass at the Large Hadron Collider
A bstractWe discuss large non-universality in the Higgs sector at high scale in supersymmetric theories, in the context of the Large Hadron Collider (LHC). In particular, we note that if $$ {{m}_{{{{H}_u}}}}^2 - {{m}_{{{{H}_d}}}}^2 $$ is large and negative $$ ( \simeq {1}{{0}^{{6}}}{\text{Ge}}{{\text{V}}^{{2}}}) $$ at high scale, the lighter slepton mass eigenstates at the electroweak scale are mostly left chiral, in contrast to a minimal supergravity (mSUGRA) scenario. We utilise this feature to explore different chiral structures of the lowest-lying sleptons, using two methods. First, we study final states with same-sign ditaus. We find that an asymmetry parameter reflecting the polarisation of the taus provides a notable distinction. In addition, we study a charge asymmetry in the jet-lepton invariant mass distribution, arising from decay chains of left-chiral squarks leading to leptons of the first two families.
13952788
Non-universal gaugino masses: a signal-based analysis for the Large Hadron Collider
We study the possible signatures of non-universal scalar masses in supersymmetry at the Large Hadron Collider (LHC). This is done, following our recent study on gaugino non-universality, via a multichannel analysis, based largely on the ratios of event rates for different final states, aimed at minimizing irregularity in the pattern due to extraneous effects and errors. We have studied (a) squark-slepton non-universality, (b) non-universality in sfermion masses of the third family, (c) the effects of SO(10) D-terms in supersymmetric Grand Unified Theories. After presenting an elaborate numerical analysis of likeand opposite-sign dileptons, inclusive and hadronically quiet trileptons as well as inclusive jet final states, we point out specific features of the spectrum in each case, which can be differentiated in the above channels from the spectrum for a minimal supergravity scenario with a universal scalar mass at high scale. The event selection criteria, and the situations where the signals are sizable enough for a comparatve study, are also delineated. It is found that, with some exceptions, the trilepton channels are likely to be especially useful for this purpose.
119226937
Supersymmetry Signals at the LHC under the most favorable SUGRA scenario
Given that it will take quite some time for the Large Hadron Collider (LHC) to reach its desired luminosity, it is important to investigate the most favorable scenario in which supersymmetry (SUSY) may be discovered at the early runs at the LHC. Our aim in this work is to find such a scenario within the gravity mediated SUSY breaking (SUGRA) framework and select a class of final states that warrant a discovery at the very early runs of the LHC. It turns out that such a situation can be associated with a scenario where gluinos are sufficiently light and so are the third generation scalars while the first two family scalars are heavy. We find that this can be achieved from a high-scale set-up with scalar mass non-universality in the third family and gaugino mass non-universality with $M_3 < M_1, M_2$. We show that the final state channels which are most favorable in such a region of parameter space are $4b+{E_{T}}\!\!\!\!/$, $4b+\ell+{E_{T}}\!\!\!\!/$ and $2b+2\ell+{E_{T}}\!\!\!\!/$. We also justify our claim by comparing the results with a minimal supergravity (mSUGRA) scenario with similar gluino mass.
26054425
Dissipative dynamics of fission in the framework of asymptotic expansion of Fokker-Planck equation

Abstract: The dynamics of fission has been formulated by generalising the asymptotic expansion of the Fokker-Planck equation in terms of the strength of the fluctuations where the diffusion coefficients depend on the stochastic variables explicitly. The prescission neutron multiplicities and mean kinetic energies of the evaporated neutrons have been calculated and compared with the respective experimental data over a wide range of excitation energy and compound nuclear mass. The mean and the variance of the total kinetic energies of the fission fragments have been calculated and compared with the experimental values.