4,454 research outputs found
Diboson production at LHC with warped extra dimensions
From the warped extra-dimensional model interpretation of the two
forward-backward asymmetries observed on heavy quarks at LEP1, AFBb, and at
Tevatron, AFBt, one predicts that LHC could observe, with the luminosity
collected in 2011-2012, significant excesses in the diboson production for
large invariant masses of the Z+W system, mZW, and, the W+W system, mWW.Comment: 15 pages, 8 figure
A 4th generation scenario
A fourth generation could provide, within SUSY, a solution to baryogenesis at
the EW scale. It is allowed by precision measurements. Available data from
Tevatron already restrict the allowed domain of parameters for the new quarks
and the Higgs boson. There are some indications from b->s transitions which
could be interpreted within an extension of the CKM matrix to 4x4, in
particular CPV in the Bs time-dependence for the J/Psi-Phi mode observed at
Tevatron. If confirmed with more data the 4MSSM interpretation predicts a very
interesting scenario for LHC and a TeV LC.Comment: Linear Collider ECFA Warsaw June 200
Scenarios for ILC in 2010
Assuming that first significant results from LHC become available, this
presentation assumes 4 different scenarios and discuss the implications for IL
Strategy to measure the Higgs mass, width and invisible decays at ILC
This document is meant to provide semi-quantitative arguments to evaluate the
luminosity needed at ILC to achieve a precise measurement of the Higgs mass,
width and invisible decays. It is shown that for mH=120 GeV, one can save an
order of magnitude on the luminosity needed to achieve a given precision on the
Higgs mass, as compared to what can be obtained at \sqrt s=350 GeV, by running
near threshold. Since the recoil mass resolution near threshold is independent
of the Higgs mass, one can also access the Higgs width for masses above 170
GeV. This strategy of running just above threshold is also optimal to measure
or set upper limits on the Higgs invisible branching ratio. Two MSSM scenarios
are presented to illustrate the potential interest of an optimized recoil mass
resolution. A simplified description of the various experimental mechanisms
affecting this type of measurement is presented: detector resolution for
leptons and jets, luminosity and beamstrahlung energy dependence, initial and
final radiation of the involved leptons.Comment: Work presented at the International Collider Physics and Detector,
ECFA Workshop, Valencia, Spain, November 7-10, 200
Efficient High-Dimensional Importance Sampling
The paper describes a simple, generic and yet highly accurate Efficient Importance Sampling (EIS) Monte Carlo (MC) procedure for the evaluation of high-dimensional numerical integrals. EIS is based upon a sequence of auxiliary weighted regressions which actually are linear under appropriate conditions. It can be used to evaluate likelihood functions and byproducts thereof, such as ML estimators, for models which depend upon unobservable variables. A dynamic stochastic volatility model and a logit panel data model with unobserved heterogeneity (random effects) in both dimensions are used to provide illustrations of EIS high numerical accuracy, even under small number of MC draws. MC simulations are used to characterize the finite sample numerical and statistical properties of EIS-based ML estimators.
Two-fluid magnetic island dynamics in slab geometry: II - Islands interacting with resistive walls or static external resonant magnetic perturbations
The dynamics of a propagating magnetic island interacting with a resistive
wall or a static external magnetic perturbation is investigated using
two-fluid, drift-MHD theory in slab geometry. In both cases, the island
equation of motion is found to take exactly the same form as that predicted by
single-fluid MHD theory. Three separate ion polarization terms are found in the
Rutherford island width evolution equation. The first is the drift-MHD
polarization term for an isolated island, and is completely unaffected by
interaction with a wall or magnetic perturbation. Next, there is the
polarization term due to interaction with a wall or magnetic perturbation which
is predicted by single-fluid MHD theory. Finally, there is a hybrid of the
other two polarization terms. The sign of this term depends on many factors.
However, under normal conditions, it is stabilizing if the unperturbed island
propagates in the ion diamagnetic direction (in the lab. frame), and
destabilizing if it propagates in the electron diamagnetic direction
Classical and Bayesian Analysis of Univariate and Multivariate Stochastic Volatility Models
In this paper, Efficient Importance Sampling (EIS) is used to perform a classical and Bayesian analysis of univariate and multivariate Stochastic Volatility (SV) models for financial return series. EIS provides a highly generic and very accurate procedure for the Monte Carlo (MC) evaluation of high-dimensional interdependent integrals. It can be used to carry out ML-estimation of SV models as well as simulation smoothing where the latent volatilities are sampled at once. Based on this EIS simulation smoother a Bayesian Markov Chain Monte Carlo (MCDC) posterior analysis of the parameters of SV models can be performed.
Learning to automatically detect features for mobile robots using second-order Hidden Markov Models
In this paper, we propose a new method based on Hidden Markov Models to
interpret temporal sequences of sensor data from mobile robots to automatically
detect features. Hidden Markov Models have been used for a long time in pattern
recognition, especially in speech recognition. Their main advantages over other
methods (such as neural networks) are their ability to model noisy temporal
signals of variable length. We show in this paper that this approach is well
suited for interpretation of temporal sequences of mobile-robot sensor data. We
present two distinct experiments and results: the first one in an indoor
environment where a mobile robot learns to detect features like open doors or
T-intersections, the second one in an outdoor environment where a different
mobile robot has to identify situations like climbing a hill or crossing a
rock.Comment: 200
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