274 research outputs found
Massively Parallel Computing at the Large Hadron Collider up to the HL-LHC
As the Large Hadron Collider (LHC) continues its upward progression in energy
and luminosity towards the planned High-Luminosity LHC (HL-LHC) in 2025, the
challenges of the experiments in processing increasingly complex events will
also continue to increase. Improvements in computing technologies and
algorithms will be a key part of the advances necessary to meet this challenge.
Parallel computing techniques, especially those using massively parallel
computing (MPC), promise to be a significant part of this effort. In these
proceedings, we discuss these algorithms in the specific context of a
particularly important problem: the reconstruction of charged particle tracks
in the trigger algorithms in an experiment, in which high computing performance
is critical for executing the track reconstruction in the available time. We
discuss some areas where parallel computing has already shown benefits to the
LHC experiments, and also demonstrate how a MPC-based trigger at the CMS
experiment could not only improve performance, but also extend the reach of the
CMS trigger system to capture events which are currently not practical to
reconstruct at the trigger level.Comment: 14 pages, 6 figures. Proceedings of 2nd International Summer School
on Intelligent Signal Processing for Frontier Research and Industry
(INFIERI2014), to appear in JINST. Revised version in response to referee
comment
Data Driven Search in the Displaced Pair Channel for a Higgs Boson Decaying to Long-Lived Neutral Particles
This article presents a proposal for a new search channel for the Higgs boson
decaying to two long-lived neutral particles, each of which decays to
at a displaced vertex. The decay length considered is such that the decay takes
place within the LHC beampipe. We present a new data-driven analysis using jet
substructure and properties of the tracks from the highly-displaced vertices.
We consider a model with a 125 GeV Higgs boson with a significant branching
fraction to decay via this mode, with the long-lived neutral particle having a
mass in the range of 15--40 GeV and a decay length commensurate with the beam
pipe radius.
Such a signal can be readily observed with an integrated luminosity of 19.5
fb at 8TeV at the LHC.Comment: 16 pages, 8 figures, Submitted to JHE
Evaluation of the Theoretical Uncertainties in the W to Lepton and Neutrino Cross Sections at the LHC
We study the sources of systematic errors in the measurement of the W to
lepton and neutrino cross-sections at the LHC. We consider the systematic
errors in both the total cross-section and acceptance for anticipated
experimental cuts. We include the best available analysis of QCD effects at
NNLO in assessing the effect of higher order corrections and PDF and scale
uncertainties on the theoretical acceptance. In addition, we evaluate the error
due to missing NLO electroweak corrections and propose which MC generators and
computational schemes should be implemented to best simulate the events.Comment: 33 pages, 109 eps figures, uses JHEP3.cls, rotating.sty Version 2
corrects an error in Table 1, adds some references, and updates an author
addres
Dilaton Supersymmetry Breaking
We argue that dilaton supersymmetry breaking in string derived supergravity
requires an effective superpotential which is not separable as a function of
the dilaton times a function of the moduli. We show that in a simple model with
hidden sector matter condensation and a dilaton independent term one can easily
obtain . For a wide range of realistic model parameters
and supersymmetry is mainly broken in the dilaton direction.Comment: 11 pages, uses phyzzx.te
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