3,612 research outputs found
A Study of Inclusive Double-Pomeron-Exchange in p pbar -> p X pbar at root s = 630 GeV
We report measurements of the inclusive reaction, p pbar -> p X pbar, in
events where either or both the beam-like final-state baryons were detected in
Roman-pot spectrometers and the central system was detected in the UA2
calorimeter. A Double-Pomeron-Exchange (DPE) analysis of these data and single
diffractive data from the same experiment demonstrates that, for central masses
of a few GeV, the extracted Pomeron-Pomeron total cross section exhibits an
enhancement which exceeds factorization expectations by an order-of-magnitude.
This may be a signature for glueball production. The enhancement is shown to be
independent of uncertainties connected with possible non-universality of the
Pomeron flux factor. Based on our analysis, we present DPE cross section
predictions, for unit (1 mb) Pomeron-Pomeron total cross section, at the
Tevatron, LHC and the 920 GeV fixed-target experiment, HERA-B.Comment: 52 pages, 27 Encapsulated Postscript figures, 3 Tables, LaTex,
Revised version as it will appear in European Physics Journal
Cross Section Measurements of Hard Diffraction at the SPS-Collider
The UA8 experiment previously reported the observation of jets in diffractive
events containing leading protons (``hard diffraction''), which was interpreted
as evidence for the partonic structure of an exchanged Reggeon, believed to be
the Pomeron . In the present Letter, we report the final UA8 hard-diffractive
(jet) cross section results and their interpretation. After corrections, the
fraction of single diffractive events with mass from 118 to 189 GeV that have
two scattered partons, each with Et_jet > 8 GeV, is in the range 0.002 to 0.003
(depending on x_p). We determine the product, fK, of the fraction by which the
Pomeron's momentum sum rule is violated and the normalization constant of the
Pomeron-Flux-Factor of the proton. For a pure gluonic- or a pure qqbar-Pomeron
, respectively: fK = 0.30 +- 0.05 +- 0.09) and (0.56 +- 0.09 +- 0.17) GeV^-2.Comment: 20 pages, 5 Encapsulated Postscript figures, LaTex, Final Version,
Physics Letters B (in Pess 1998
Search for a Standard Model Higgs Boson in CMS via Vector Boson Fusion in the H->WW->l\nu l\nu Channel
We present the potential for discovering the Standard Model Higgs boson
produced by the vector-boson fusion mechanism. We considered the decay of Higgs
bosons into the W+W- final state, with both W-bosons subsequently decaying
leptonically. The main background is ttbar with one or more jets produced. This
study is based on a full simulation of the CMS detector, and up-to-date
reconstruction codes. The result is that a signal of 5 sigma significance can
be obtained with an integrated luminosity of 12-72 1/fb for Higgs boson masses
between 130-200 GeV. In addition, the major background can be measured directly
to 7% from the data with an integrated luminosity of 30 1/fb. In this study, we
also suggested a method to obtain information in Higgs mass using the
transverse mass distributions.Comment: 26 pages, 22 figure
Groundwater level assessment and prediction in the Nebraska Sand Hills using LIDAR-derived lake water level
The spatial variability of groundwater levels is often inferred from sparsely located hydraulic head observations in wells. The spatial correlation structure derived from sparse observations is associated with uncertainties that spread to estimates at unsampled locations. In areas where surface water represents the nearby groundwater level, remote sensing techniques can estimate and increase the number of hydraulic head measurements. This research uses light detection and ranging (LIDAR) to estimate lake surface water level to characterize the groundwater level in the Nebraska Sand Hills (NSH), an area with few observation wells. The LIDAR derived lake groundwater level accuracy was within 40 cm mean square error (MSE) of the nearest observation wells. The lake groundwater level estimates were used to predict the groundwater level at unsampled locations using universal kriging (UK) and kriging with an external drift (KED). The results indicate unbiased estimates of groundwater level in the NSH. UK showed the influence of regional trends in groundwater level while KED revealed the local variation present in the groundwater level. A 10-fold cross-validation demonstrated KED with better mean squared error (ME) [â0.003, 0.007], root mean square error (RMSE) [2.39, 4.46], residual prediction deviation (RPD) [1.32, 0.71] and mean squared deviation ratio (MSDR) [1.01, 1.49] than UK. The research highlights that the lake groundwater level provides an accurate and cost-effective approach to measure and monitor the subtle changes in groundwater level in the NSH. This methodology can be applied to other locations where surface water bodies represent the water level of the unconfined aquifer and the results can aid in groundwater management and modeling
The Semileptonic to Decays in QCD Sum Rules
We analyze the semileptonic rare decays of meson to and
axial vector mesons. The
decays are significant flavor changing neutral current decays of the meson.
These decays are sensitive to the new physics beyond SM, since these processes
are forbidden at tree level at SM. These decays occurring at the quark level
via transition, also provide new opportunities for
calculating the CKM matrix elements and . In this study, the
transition form factors of the decays
are calculated using three-point QCD sum rules approach. The resulting form
factors are used to estimate the branching fractions of these decays.Comment: 18 pages, 7 figures, version to appear in JP
Using a discourse bank and a lexicon for the automatic identification of discourse connectives
We describe two new resources that have been prepared for European Portuguese and how they are used for discourse parsing: the Portuguese subpart of the TED-MDB corpus, a multilingual corpus of TED Talks that has been annotated in the PDTB style, and the Lexicon of Discourse Markers for Portuguese (LDM-PT). Both lexicon and corpus are used in a preliminary experiment for discourse connective identification in texts. This includes, in many cases, the difficult task of disambiguating between connective and non-connective uses. We annotated the PT-TED-MDB corpus with POS, lemma and syntactic constituency and focus on the 10 most frequent connectives in the corpus. The best approach considers word-form+POS+syntactic annotation and leads to 85% precision.info:eu-repo/semantics/publishedVersio
Leading order analysis of neutrino induced dimuon events in the CHORUS experiment
We present a leading order QCD analysis of a sample of neutrino induced
charged-current events with two muons in the final state originating in the
lead-scintillating fibre calorimeter of the CHORUS detector. The results are
based on a sample of 8910 neutrino and 430 antineutrino induced opposite-sign
dimuon events collected during the exposure of the detector to the CERN Wide
Band Neutrino Beam between 1995 and 1998. % with GeV
and GeV collected %between 1995 and 1998. The analysis yields a
value of the charm quark mass of \mc = (1.26\pm 0.16 \pm 0.09) \GeVcc and a
value of the ratio of the strange to non-strange sea in the nucleon of , improving the results obtained in similar analyses
by previous experiments.Comment: Submitted to Nuclear Physics
The trigger system of the CHORUS experiment
A new apparatus for detection of oscillation has been successfully constructed and operated by the CHORUS Collaboration for the CERN-WA95 experiment. The design , implementation and performance of the electronic trigger system is described. A trigger efficiency of 99 was measured for charged current events and 90 for neutral current e vents
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
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