5,380 research outputs found
The First Year of the Large Hadron Collider: A Brief Review
The first year of LHC data taking provided an integrated luminosity of about
35/pb in proton-proton collisions at sqrt(s)=7 TeV. The accelerator and the
experiments have demonstrated an excellent performance. The experiments have
obtained important physics results in many areas, ranging from tests of the
Standard Model to searches for new particles. Among other results the physics
highlights have been the measurements of the W-, Z-boson and t t-bar production
cross-sections, improved limits on supersymmetric and other hypothetical
particles and the observation of jet-quenching, elliptical flow and J/Psi
suppression in lead-lead collisions at sqrt(sNN) = 2.76 TeV.Comment: 11 pages, 9 figures, invited brief review for Mod. Phys. Lett.
Exploring singlet deflection of gauge mediation
We embed the Next-to Minimal Supersymmetric Standard Model into gauge
mediation of supersymmetry breaking and study the phenomenology of scenarios
where the gauge-mediation contributions to soft parameters are deflected by
superpotential interactions of the gauge singlet with the messenger fields and
the Higgs doublets. This kind of models provide a satisfactory solution to the
mu-b_mu problem of gauge mediation, compatible with the adequate pattern of
electroweak symmetry breaking and a realistic spectrum with supersymmetric
partners at the TeV scale without requiring a significant fine tuning.Comment: Latex 18 pages, 4 eps figures. Minor corrections, version published
in Phys. Rev.
Search for W′ → tb in proton-proton collisions at s√=8 TeV
A search is performed for the production of a massive W′ boson decaying to a top and a bottom quark. The data analysed correspond to an integrated luminosity of 19.7 fb−1 collected with the CMS detector at the LHC in proton-proton collisions at s √ =8
s=8
TeV. The hadronic decay products of the top quark with high Lorentz boost from the W′ boson decay are detected as a single top flavoured jet. The use of jet substructure algorithms allows the top quark jet to be distinguished from standard model QCD background. Limits on the production cross section of a right-handed W′ boson are obtained, together with constraints on the left-handed and right-handed couplings of the W′ boson to quarks. The production of a right-handed W′ boson with a mass below 2.02 TeV decaying to a hadronic final state is excluded at 95% confidence level. This mass limit increases to 2.15 TeV when both hadronic and leptonic decays are considered, and is the most stringent lower mass limit to date in the tb decay mode
Measurement of inclusive W and Z cross sections in pp collisions at √s = 7 TeV
Journal of High Energy Physics 2011.1 (2011): 080 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)Measurements of inclusive W and Z boson production cross sections in pp collisions at √s = 7 TeV are presented, based on 2.9 pb-1 of data recorded by the CMS detector at the LHC. The measurements, performed in the electron and muon decay channels, are combined to give σ(pp → WX) × B(W → lʋ) = 9.95 ± 0.07 (stat.) ± 0.28 (syst.) ± 1.09 (lumi.) nb and σ(pp → ZX) × B(Z → l +l-) = 0.931 ± 0.026 (stat.) ± 0.023 (syst.) ± 0.102 (lumi.) nb, where ℓ stands for either e or μ. Theoretical predictions, calculated at the next-to-next-to-leading order in QCD using recent parton distribution functions, are in agreement with the measured cross sections. Ratios of cross sections, which incur an experimental systematic uncertainty of less than 4%, are also reporte
The estimation of neutrino fluxes produced by proton-proton collisions at TeV of the LHC
Intense and collimated neutrino beams are produced by charm and beauty
particle decays from proton-proton collisions at the LHC. A neutrino experiment
would be run parasitically without interrupting the LHC physics program during
the collider run. We estimate the neutrino fluxes from proton-proton collisions
at TeV of the LHC with the designed luminosity, 10^{34} \lumi.
By mounting about 200 tons of fiducial volume of a neutrino detector at 300
\m away from the interaction point, about 150,000 of charged current neutrino
events per year can be observable.Comment: 8 pages, Accepted in JHE
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