4,591 research outputs found
A uniform law of large numbers for functions of i.i.d. random variables that are translated by a consistent estimator
We develop a new law of large numbers where the -th summand is given
by a function evaluated at , and where is an estimator converging in probability
to some parameter . Under broad technical conditions, the
convergence is shown to hold uniformly in the set of estimators interpolating
between and another consistent estimator . Our main
contribution is the treatment of the case where blows up at , which is
not covered by standard uniform laws of large numbers.Comment: 10 pages, 1 figur
The Hellinger Correlation
In this paper, the defining properties of a valid measure of the dependence
between two random variables are reviewed and complemented with two original
ones, shown to be more fundamental than other usual postulates. While other
popular choices are proved to violate some of these requirements, a class of
dependence measures satisfying all of them is identified. One particular
measure, that we call the Hellinger correlation, appears as a natural choice
within that class due to both its theoretical and intuitive appeal. A simple
and efficient nonparametric estimator for that quantity is proposed. Synthetic
and real-data examples finally illustrate the descriptive ability of the
measure, which can also be used as test statistic for exact independence
testing
SUSY parameter determination
The impact of the LHC, SLHC and the ILC on the precision of the determination
of supersymmetric parameters is investigated. In particular, in the point SPS1a
the measurements performed at the ILC will improve by an order of magnitude the
precision obtained by the LHC alone. The SLHC with respect to the LHC has the
potential to reduce the errors by a factor two.Comment: Invited talk at 2005 International Linear Collider Physics and
Detector Workshop and Second ILC Accelerator Workshop, Snowmass,
CO(Snowmass05) 3 pages, LaTe
SFITTER: SUSY Parameter Analysis at LHC and LC
SFITTER is a new analysis tool to determine supersymmetric model parameters
from collider measurements. Using the set of supersymmetric mass measurements
at the LC and at the LHC we show how both colliders probe different sectors of
the MSSM Lagrangian. This observation is a strong motivation to move from a
parameter fit assuming a certain model to the unconstrained weak-scale MSSM
Lagrangian. We argue how the technical challenges can be dealt with in a
combined fit/grid approach with full correlations.Comment: contribution to LHC-LC Study Group, G.Weiglein et a
SFitter: Reconstructing the MSSM Lagrangian from LHC data
Once supersymmetry is found at the LHC, the question arises what are the
fundamental parameters of the Lagrangian. The answer to this question should
thereby not be biased by assumptions on high-scale models. SFitter is a tool
designed for this task. Taking LHC (and possibly ILC) data as input it scans
the TeV-scale MSSM parameter space using its new weighted Markov chain
technique. Using this scan it determines a list of best-fitting parameter
points. Additionally a log-likelihood map is calculated, which can be reduced
to lower-dimensional Frequentist's profile likelihoods or Bayesian probability
maps.Comment: Submitted for the SUSY07 proceedings, 4 pages, LaTeX, 4 eps figure
Double Higgs production at TeV Colliders in the Minimal Supersymmetric Standard Model
The reconstruction of the Higgs potential in the Minimal Supersymmetric
Standard Model (MSSM) requires the measurement of the trilinear Higgs
self-couplings. The `double Higgs production' subgroup has been investigating
the possibility of detecting signatures of processes carrying a dependence on
these vertices at the Large Hadron Collider (LHC) and future Linear Colliders
(LCs). As reference reactions, we have chosen and ,
respectively, where is the lightest of the MSSM Higgs bosons. In both
cases, the interaction is involved. For , the two reactions are
resonant in the mode, providing cross sections which are detectable
at both accelerators and strongly sensitive to the strength of the trilinear
coupling involved. We explore this mass regime of the MSSM in the decay channel, also accounting for irreducible background effects.Comment: LaTeX, 23 pages, 13 PostScript figures (contribution to the Summary
Report of the Higgs WG, Workshop `Physics at TeV Colliders', Les Houches,
France, 8-18 June 1999): some modifications to the bibliograph
Measuring Higgs Couplings from LHC Data
Following recent ATLAS and CMS publications we interpret the results of their
Higgs searches in terms of Standard Model operators. For a Higgs mass of 125
GeV we determine several Higgs couplings from 2011 data and extrapolate the
results towards different scenarios of LHC running. Even though our analysis is
limited by low statistics we already derive meaningful constraints on modified
Higgs sectors.Comment: 5 pages, 4 figure
ATLAS electromagnetic barrel calorimeter performance in recent testbeams
During the combined testbeam in summer 2004 a slice of the ATLAS barrel detectorâincluding all detector sub systems from the inner tracker, the calorimetry to the muon systemâwas exposed to particle beams (electrons, pions, photons, muons) with different energies (1â350 GeV). The aim was to study the combined performance of the different detector sub systems in ATLAS-like conditions. We will present studies with different amounts of material in front of the calorimeter, representing various regions in the ATLAS detector, performance results from the electromagnetic calorimetry, including uniformity, resolution, and linearity as well as a discussion of the calibration scheme. The performance in the combined ATLAS-like set-up will be compared to the one obtained in stand-alone testbeams
Photon Production at the LHC
We review the last results on photon production at LHC by the ATLAS and CMS experiments obtained in proton-proton collisions with a center of mass energy of 7 TeV. We discuss the impact of prompt photon and photon-jet differential cross-sections, on the parton distribution function of the proton. Di-photon differential cross-sections are also presented as a function of the di-photon invariant mass, transverse momentum, azimuthal separation, and cos theta*
Measuring Supersymmetry with Heavy Scalars
Supersymmetry with heavy scalars is a model where at the LHC we have to rely
on rate measurements to determine the parameters of the underlying new physics.
For this example we show how to properly combine rate measurements with
kinematic endpoints, taking into account statistical, systematic and theory
uncertainties. Provided we observe a sizeable number of events the LHC should
be able to determine many model parameters with small enough error bars to for
example test unification patterns.Comment: 13 pages, 8 table
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