1,902 research outputs found
Luminosity Spectrum Reconstruction at Linear Colliders
A good knowledge of the luminosity spectrum is mandatory for many
measurements at future e+e- colliders. As the beam-parameters determining the
luminosity spectrum cannot be measured precisely, the luminosity spectrum has
to be measured through a gauge process with the detector. The measured
distributions, used to reconstruct the spectrum, depend on Initial State
Radiation, cross-section, and Final State Radiation. To extract the basic
luminosity spectrum, a parametric model of the luminosity spectrum is created,
in this case the spectrum at the 3 TeV Compact Linear Collider (CLIC). The
model is used within a reweighting technique to extract the luminosity spectrum
from measured Bhabha event observables, taking all relevant effects into
account. The centre-of-mass energy spectrum is reconstructed within 5% over the
full validity range of the model. The reconstructed spectrum does not result in
a significant bias or systematic uncertainty in the exemplary physics benchmark
process of smuon pair production.Comment: Version accepted by EPJC. Minor change
On frequency and time domain models of traveling wave tubes
We discuss the envelope modulation assumption of frequency-domain models of
traveling wave tubes (TWTs) and test its consistency with the Maxwell
equations. We compare the predictions of usual frequency-domain models with
those of a new time domain model of the TWT
Collisional Energy Loss of a Fast Muon in a Hot QED Plasma
We calculate the collisional energy loss of a muon of high energy in a
hot QED plasma beyond logarithmic accuracy, i.e., we determine the constant
terms of order O(1) in . Considering first the
-channel contribution to , we show that the terms are
sensitive to the full kinematic region for the momentum exchange in elastic
scattering, including large values . We thus redress a previous
calculation by Braaten and Thoma, which assumed and could not find the
correct constant (in the large limit). The relevance of 'very hard'
momentum transfers then requires, for consistency, that and -channel
contributions from Compton scattering must be included, bringing a second
modification to the Braaten-Thoma result. Most importantly, Compton scattering
yields an additional large logarithm in . Our results might have
implications in the QCD case of parton collisional energy loss in a quark gluon
plasma.Comment: 26 pages, 3 figures, JHEP styl
Quantitative ergodicity for some switched dynamical systems
We provide quantitative bounds for the long time behavior of a class of
Piecewise Deterministic Markov Processes with state space Rd \times E where E
is a finite set. The continuous component evolves according to a smooth vector
field that switches at the jump times of the discrete coordinate. The jump
rates may depend on the whole position of the process. Under regularity
assumptions on the jump rates and stability conditions for the vector fields we
provide explicit exponential upper bounds for the convergence to equilibrium in
terms of Wasserstein distances. As an example, we obtain convergence results
for a stochastic version of the Morris-Lecar model of neurobiology
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