13,800 research outputs found
Exclusive processes in pp collisions in CMS
We report the results on the searches of exclusive production of low- and
high-mass pairs with the Compact Muon Solenoid (CMS) detector in proton-proton
collisions at = 7 TeV. The analyses comprise the central exclusive
production, the exclusive two-photon production of dileptons,
and , and the exclusive two-photon production of
pairs in the asymmetric decay channel. No diphotons
candidates are observed in data and an upper limit on the cross section is set
to 1.18 pb with 95% confidence level for 5.5 GeV and
2.5. In the measurement of exclusive dilepton production,
seventeen candidates are observed in data with 5.5 GeV
and 2.5, and the cross section for the exclusive dimuon production
is set to (stat.)
0.16 (syst.) 0.14 (lumi.) pb for 11.5 GeV,
4 GeV and 2.1, both in agreement with the
theoretical predictions. For high-mass systems, two events are observed in data
for the exclusive two-photon production of pairs for
4 GeV, 20 GeV. Moreover, the
study of the tail of the dilepton transverse momentum distribution resulted in
model-independent upper limits for the anomalous quartic gauge couplings, which
are of the order of 10.Comment: 7 pages, 6 figures, presented at the XXI International Workshop on
Deep-Inelastic Scattering and Related Subjects, April 2013, Marseille, Franc
Diffractive Higgs boson photoproduction in peripheral collisions
An alternative process is proposed for the diffractive Higgs boson production
in peripheral collisions, exploring it through the photon-proton
interaction by Double Pomeron Exchange. It is estimated the event rate of the
diffractive Higgs production in central rapidity for Tevatron and LHC energies,
being of the order of 1 fb, in agreement to the predictions from other
diffractive processes. The results are confronted with those obtained from a
similar approach of the Durham group.Comment: 4 pages, 7 figures, contribution to the proceedings of II Latin
American Workshop on High Energy Physics [IILAWHEP], 3-7 Dec. 2007, Sao
Miguel das Missoes, Brazi
Single and Central Diffractive Higgs Production at the LHC
The single and central diffractive production of the Standard Model Higgs
boson is computed using the diffractive factorization formalism, taking into
account a parametrization for the Pomeron structure function provided by the H1
Collaboration. We compute the cross sections at NLO accuracy for the gluon
fusion process, since it is the leading mechanism for the Higgs boson
production. The gap survival probability is also introduced to include the
rescattering corrections due to spectator particles present in the interaction.
The diffractive ratios are predicted for proton-proton collisions at the LHC,
since the beam luminosity is favorable to the Higgs boson detection. These
results provide updated estimations for the fraction of single and central
diffractive events in the LHC kinematical regime.Comment: To appear in the proceedings of Diffraction 2010: International
Workshop on Diffraction in High Energy Physics, Otranto, Italy, 10-15 Sep
201
Local vs. long-range infection in unidimensional epidemics
We study the effects of local and distance interactions in the unidimensional
contact process (CP). In the model, each site of a lattice is occupied by an
individual, which can be healthy or infected. As in the standard CP, each
infected individual spreads the disease to one of its first-neighbors with rate
, and with unitary rate, it becomes healthy. However, in our model, an
infected individual can transmit the disease to an individual at a distance
apart. This step mimics a vector-mediated transmission. We observe the
host-host interactions do not alter the critical exponents significantly in
comparison to a process with only L\'evy-type interactions. Our results
confirm, numerically, early field-theoretic predictions.Comment: 8 pages, 6 figures, to appear on Frontiers in Physic
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