396 research outputs found
HEPCloud, a New Paradigm for HEP Facilities: CMS Amazon Web Services Investigation
Historically, high energy physics computing has been performed on large
purpose-built computing systems. These began as single-site compute facilities,
but have evolved into the distributed computing grids used today. Recently,
there has been an exponential increase in the capacity and capability of
commercial clouds. Cloud resources are highly virtualized and intended to be
able to be flexibly deployed for a variety of computing tasks. There is a
growing nterest among the cloud providers to demonstrate the capability to
perform large-scale scientific computing. In this paper, we discuss results
from the CMS experiment using the Fermilab HEPCloud facility, which utilized
both local Fermilab resources and virtual machines in the Amazon Web Services
Elastic Compute Cloud. We discuss the planning, technical challenges, and
lessons learned involved in performing physics workflows on a large-scale set
of virtualized resources. In addition, we will discuss the economics and
operational efficiencies when executing workflows both in the cloud and on
dedicated resources.Comment: 15 pages, 9 figure
Search for charged Higgs decays of the top quark using hadronic tau decays
We present the result of a search for charged Higgs decays of the top quark,
produced in collisions at 1.8 TeV. When the charged
Higgs is heavy and decays to a tau lepton, which subsequently decays
hadronically, the resulting events have a unique signature: large missing
transverse energy and the low-charged-multiplicity tau. Data collected in the
period 1992-1993 at the Collider Detector at Fermilab, corresponding to
18.70.7~pb, exclude new regions of combined top quark and charged
Higgs mass, in extensions to the standard model with two Higgs doublets.Comment: uuencoded, gzipped tar file of LaTeX and 6 Postscript figures; 11 pp;
submitted to Phys. Rev.
Inclusive jet cross section in collisions at TeV
The inclusive jet differential cross section has been measured for jet
transverse energies, , from 15 to 440 GeV, in the pseudorapidity region
0.10.7. The results are based on 19.5 pb of data
collected by the CDF collaboration at the Fermilab Tevatron collider. The data
are compared with QCD predictions for various sets of parton distribution
functions. The cross section for jets with GeV is significantly
higher than current predictions based on O() perturbative QCD
calculations. Various possible explanations for the high- excess are
discussed.Comment: 8 pages with 2 eps uu-encoded figures Submitted to Physical Review
Letter
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
Measurement of Dijet Angular Distributions at CDF
We have used 106 pb^-1 of data collected in proton-antiproton collisions at
sqrt(s)=1.8 TeV by the Collider Detector at Fermilab to measure jet angular
distributions in events with two jets in the final state. The angular
distributions agree with next to leading order (NLO) predictions of Quantum
Chromodynamics (QCD) in all dijet invariant mass regions. The data exclude at
95% confidence level (CL) a model of quark substructure in which only up and
down quarks are composite and the contact interaction scale is Lambda_ud(+) <
1.6 TeV or Lambda_ud(-) < 1.4 TeV. For a model in which all quarks are
composite the excluded regions are Lambda(+) < 1.8 TeV and Lambda(-) < 1. 6
TeV.Comment: 16 pages, 2 figures, 2 tables, LaTex, using epsf.sty. Submitted to
Physical Review Letters on September 17, 1996. Postscript file of full paper
available at http://www-cdf.fnal.gov/physics/pub96/cdf3773_dijet_angle_prl.p
Measurement of correlated jet cross sections in collisions at TeV
We report on measurements of differential cross sections,
where the muon is from a semi-leptonic decay and the is
identified using precision track reconstruction in jets. The semi-differential
correlated cross sections, d/d\Et^{{\bar b}}, d/d\pt^{{\bar
b}}, and d/d for \pt^{\mu}>~9 GeV/c,
~10 GeV, ~1.5, are
presented and compared to next-to-leading order QCD calculations.Comment: Uses Latex, Article 12 point, figures appended as uuencoded file The
full PostScript available via WWW at
http://www-cdf.fnal.gov/physics/pub95/cdf3164_mu_bbar_prd_final.p
Measurement of the Meson Differential Cross Section, , in Collisions at TeV
This paper presents the first direct measurement of the meson
differential cross section, , in collisions at
TeV using a sample of pb accumulated by
the Collider Detector at Fermilab (CDF). The cross section is measured in the
central rapidity region GeV/ by fully
reconstructing the meson decays and , where and .
A comparison is made to the theoretical QCD prediction calculated at
next-to-leading order.Comment: 14 pages. Submitted to Phys. Rev. Lett. The postscript file is at
http://www-cdf.fnal.gov/physics/pub95/cdf2893_bexcl_xsection.p
Search for New Particles Decaying to Dijets in p-pbar Collisions at sqrt(s)=1.8 TeV
We have used 19 pb**-1 of data collected with the Collider Detector at
Fermilab to search for new particles decaying to dijets. We exclude at 95%
confidence level models containing the following new particles: axigluons with
mass between 200 and 870 GeV, excited quarks with mass between 80 and 570 GeV,
and color octet technirhos with mass between 320 and 480 GeV.Comment: Submitted to Physical Review Letters in December 199
The Charge Asymmetry in W-Boson Decays Produced in p-pbar Collisions at sqrt(s) = 1.8 TeV
The charge asymmetry has been measured using decays recorded by
the CDF detector during the 1992-93 run of the Tevatron Collider. The asymmetry
is sensitive to the ratio of and quark distributions to at
, where nonperturbative effects are minimal. It is found
that of the two current sets of parton distributions, those of Martin, Roberts
and Stirling (MRS) are favored over the sets most recently produced by the CTEQ
collaboration. The asymmetry data provide a stronger constraints on
ratio than the recent measurements of which are
limited by uncertainties originating from deutron corrections.Comment: to be published in PR
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