5,539 research outputs found
Lepton flavour violating slepton decays to test type-I and II seesaw at the LHC
Searches at the LHC of lepton flavour violation (LFV) in slepton decays can
indirectly test both type-I and II seesaw mechanisms. Assuming universal
flavour-blind boundary conditions, LFV in the neutrino sector is related to LFV
in the slepton sector by means of the renormalization group equations. Ratios
of LFV slepton decay rates result to be a very effective way to extract the
imprint left by the neutrino sector. Some neutrino scenarios within the type-I
seesaw mechanism are studied. Moreover, for both type-I and II seesaw
mechanisms, a scan over the minimal supergravity parameter space is performed
to estimate how large LFV slepton decay rates can be, while respecting current
low-energy constraints.Comment: 4 pages; to appear in the proceedings of the 17th International
Conference on Supersymmetry and the Unification of Fundamental Interactions
(SUSY09), Boston (MA), USA, 5-10 Jun 200
A Berry-Esseen theorem for Feynman-Kac and interacting particle models
In this paper we investigate the speed of convergence of the fluctuations of
a general class of Feynman-Kac particle approximation models. We design an
original approach based on new Berry-Esseen type estimates for abstract
martingale sequences combined with original exponential concentration estimates
of interacting processes. These results extend the corresponding statements in
the classical theory and apply to a class of branching and genealogical
path-particle models arising in nonlinear filtering literature as well as in
statistical physics and biology.Comment: Published at http://dx.doi.org/10.1214/105051604000000792 in the
Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute
of Mathematical Statistics (http://www.imstat.org
Genealogical particle analysis of rare events
In this paper an original interacting particle system approach is developed
for studying Markov chains in rare event regimes. The proposed particle system
is theoretically studied through a genealogical tree interpretation of
Feynman--Kac path measures. The algorithmic implementation of the particle
system is presented. An estimator for the probability of occurrence of a rare
event is proposed and its variance is computed, which allows to compare and to
optimize different versions of the algorithm. Applications and numerical
implementations are discussed. First, we apply the particle system technique to
a toy model (a Gaussian random walk), which permits to illustrate the
theoretical predictions. Second, we address a physically relevant problem
consisting in the estimation of the outage probability due to polarization-mode
dispersion in optical fibers.Comment: Published at http://dx.doi.org/10.1214/105051605000000566 in the
Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute
of Mathematical Statistics (http://www.imstat.org
On the Geometry of Sculpting-like Gauging Processes
Recently, a new gauging procedure called Sculpting mechanism was proposed to
obtain the M-theory origin of type II gauged Supergravity theories in 9D. We
study this procedurein detail and give a better understanding of the different
deformations and changes in fiber bundles, that are able to generate new
relevant physical gauge symmetries in the theory. We discuss the geometry
involved in the standard approach (Noether-like) and in the new Scultping-like
one and comment on possible new applications.Comment: 9 pages, latex, Notation and typos reviewed, more clear explanations,
results unchange
Interacting Markov chain Monte Carlo methods for solving nonlinear measure-valued equations
We present a new class of interacting Markov chain Monte Carlo algorithms for
solving numerically discrete-time measure-valued equations. The associated
stochastic processes belong to the class of self-interacting Markov chains. In
contrast to traditional Markov chains, their time evolutions depend on the
occupation measure of their past values. This general methodology allows us to
provide a natural way to sample from a sequence of target probability measures
of increasing complexity. We develop an original theoretical analysis to
analyze the behavior of these iterative algorithms which relies on
measure-valued processes and semigroup techniques. We establish a variety of
convergence results including exponential estimates and a uniform convergence
theorem with respect to the number of target distributions. We also illustrate
these algorithms in the context of Feynman-Kac distribution flows.Comment: Published in at http://dx.doi.org/10.1214/09-AAP628 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Sequential Monte Carlo Methods for Option Pricing
In the following paper we provide a review and development of sequential
Monte Carlo (SMC) methods for option pricing. SMC are a class of Monte
Carlo-based algorithms, that are designed to approximate expectations w.r.t a
sequence of related probability measures. These approaches have been used,
successfully, for a wide class of applications in engineering, statistics,
physics and operations research. SMC methods are highly suited to many option
pricing problems and sensitivity/Greek calculations due to the nature of the
sequential simulation. However, it is seldom the case that such ideas are
explicitly used in the option pricing literature. This article provides an
up-to date review of SMC methods, which are appropriate for option pricing. In
addition, it is illustrated how a number of existing approaches for option
pricing can be enhanced via SMC. Specifically, when pricing the arithmetic
Asian option w.r.t a complex stochastic volatility model, it is shown that SMC
methods provide additional strategies to improve estimation.Comment: 37 Pages, 2 Figure
- …