6,624 research outputs found
Study of the electron trigger efficiency of the CMS Experiment using test beam data
A study of the electron identification and selection efficiency of the L1
Trigger algorithm has been performed using the combined ECAL/HCAL test beam
data. A detailed discussion of the electron isolation and its impact on the
selection efficiency is presented. The L1 electron algorithm is studied for
different beam energies and the results indicate that efficiencies of 98% or
more can be achieved for electrons with energies between 15 and 100 GeV. The
fraction of charged hadrons with energies from 3 up to 100 GeV rejected by the
L1 electron trigger algorithm is estimated to be larger than 93%.Comment: 22 pages, 14 figure
Central exclusive production of scalar \chi_c meson at the Tevatron, RHIC and LHC energies
We calculate several differential distributions for exclusive double
diffractive production in proton-antiproton collisions at the
Tevatron and in proton-proton collisions at RHIC and LHC in terms of
unintegrated gluon distributions (UGDFs) within the -factorisation
approach. The uncertainties of the Khoze-Martin-Ryskin approach are discussed
in detail. The transition vertex is calculated as
a function of gluon virtualities applying the standard pNRQCD technique. The
off-shell effects are discussed and quantified. They lead to a reduction of the
cross section by a factor 2--5, depending on the position in the phase space
and UGDFs. Different models of UGDFs are used and the results are shown and
discussed. The cross section for diffractive component depends strongly on
UGDFs. We calculate also the differential distributions for the fusion mechanism. The integrated cross section for
photon-photon fusion is much smaller than that of diffractive origin. The two
components have very different dependence on momentum transfers in
the nucleon lines as well as azimuthal-angle correlations between both outgoing
nucleons.Comment: 34 pages, 23 figures, 2 table
Data filtering in the readout of the CMS Electromagnetic Calorimeter
For an efficient data taking, the Electromagnetic Calorimeter (ECAL) data of the CMS experiment must be limited to 10\% of the full event size (1MB). Other requirements limit the average data size to 2kB per data acquisition link. These conditions imply a reduction factor of close to twenty on the data collected. The data filtering in the readout of the ECAL detector is discussed. Test beam data are used to study the digital filtering applied in the readout channels and a full detector simulation allows to estimate the energy thresholds to achieve the desired data suppression factor
The Microcalorimeter Arrays for a Rhenium Experiment (MARE): a next-generation calorimetric neutrino mass experiment
Neutrino oscillation experiments have proved that neutrinos are massive
particles, but can't determine their absolute mass scale. Therefore the
neutrino mass is still an open question in elementary particle physics. An
international collaboration is growing around the project of Microcalorimeter
Arrays for a Rhenium Experiment (MARE) for directly measuring the neutrino mass
with a sensitivity of about 0.2eV/c2. Many groups are joining their experiences
and technical expertise in a common effort towards this challenging experiment.
We discuss the different scenarios and the impact of MARE as a complement of
KATRIN.Comment: 3 pages, 1 figure Nucl. Instr. Meth. A, proceedings of LTD11
workshop, Tokyo 200
On the Early History of Current Algebra
The history of Current Algebra is reviewed up to the appearance of the
Adler-Weisberger sum rule. Particular emphasis is given to the role current
algebra played for the historical struggle in strong interaction physics of
elementary particles between the S-matrix approach based on dispersion
relations and field theory. The question whether there are fundamental
particles or all hadrons are bound or resonant states of one another played an
important role in this struggle and is thus also regarded.Comment: 17 page
Heavy Flavours in Collider Experiments
Current issues in the studies of Heavy Flavours in colliders are described
with particular emphasis on experiments in which the UK is involved. Results on
charm production at HERA are examined and compared to those at the Tevatron. B
production rates at the Tevatron as well as the status of B lifetimes and
mixing in the LEP collaborations and at the Tevatron are highlighted. The
measurement of sin2beta from CDF is described as well as the most recent
results on top physics at the Tevatron
Tevatron-for-LHC Report of the QCD Working Group
The experiments at Run 2 of the Tevatron have each accumulated over 1 inverse
femtobarn of high-transverse momentum data. Such a dataset allows for the first
precision (i.e. comparisons between theory and experiment at the few percent
level) tests of QCD at a hadron collider. While the Large Hadron Collider has
been designed as a discovery machine, basic QCD analyses will still need to be
performed to understand the working environment. The Tevatron-for-LHC workshop
was conceived as a communication link to pass on the expertise of the Tevatron
and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD
Working Group focussed on important aspects of QCD at hadron colliders: jet
definitions, extraction and use of Parton Distribution Functions, the
underlying event, Monte Carlo tunes, and diffractive physics. This report
summarizes some of the results achieved during this workshop.Comment: 156 pages, Tevatron-for-LHC Conference Report of the QCD Working
Grou
Measurement of J/Psi and Psi(2S) Polarization in ppbar Collisions at sqrt(s) = 1.8 TeV
We have measured the polarization of J/Psi and Psi(2S) mesons produced in
p\bar{p} collisions at \sqrt{s} = 1.8 TeV, using data collected at CDF during
1992-95.
The polarization of promptly produced J/Psi [Psi(2S)] mesons is isolated from
those produced in B-hadron decay, and measured over the kinematic range 4[5.5]
< P_T < 20 GeV/c and |y| < 0.6. For P_T \gessim 12 GeV/c we do not observe
significant polarization in the prompt component.Comment: Revised version, accepted for publication in Physical Review Letter
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