Helen F Heath

Search for resonant t t-bar production in lepton+jets events in pp collisions at sqrt(s) = 7 TeV

A bstractA model-independent search for the production of heavy resonances decaying into top-antitop quark pairs is presented. The search is based on events containing one lepton (muon or electron) and at least two jets selected from data samples corresponding to an integrated luminosity of 4.4-5.0 fb−1 collected in pp collisions at

Search for resonance decays to an anti-neutrino plus jet in E + P scattering at DESY HERA

\sqrt{s}=7

Measurement of the Inclusive

TeV. Results are presented from the combination of two dedicated searches optimized for boosted production and production at threshold. No excess of events is observed over the expected yield from the standard model processes. Topcolor Z′ bosons with narrow (wide) width are excluded at 95% confidence level for masses below 1.49 (2.04) TeV and an upper limit of 0.3 (1.3) pb or lower is set on the production cross section times branching fraction for resonance masses above 1 TeV. Kaluza-Klein excitations of a gluon with masses below 1.82 TeV (at 95% confidence level) in the Randall-Sundrum model are also excluded, and an upper limit of 0.7 pb or lower is set on the production cross section times branching fraction for resonance masses above 1 TeV.

W

A study of the {anti {nu}}-jet mass spectrum in e{sup +}p{yields}{anti {nu}} X events at a center-of-mass energy 300 GeV has been performed with the ZEUS detector at the HERA collider at DESY using an integrated luminosity of 47.7 pb{sup -1}. The mass spectrum is in good agreement with that expected from standard model processes over the {anti {nu}}-jet mass range studied. No significant excess attributable to the decay of a narrow resonance is observed. By using both e{sup +}p {yields} e{sup +}X and e{sup +}p {yields} {anti {nu}} X data, mass-dependent limits are set on the s-channel production of scalar and vector resonant states. Couplings to first-generation quarks are considered and limits are presented as a function of the e{sup +}q and {anti {nu}} q branching ratios. These limts are used to constrain the production of leptoquarks and R-parity violating squarks.

and

A measurement of inclusive W and Z production cross sections in pp collisions at √ s = 7 TeV is presented. The electron and muon decay channels are analyzed in a data sample collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 36 pb−1. The measured inclusive cross sections are σ(pp → WX) × B(W → `ν) = 10.30 ± 0.02 (stat.) ± 0.10 (syst.) ± 0.10 (th.) ± 0.41 (lumi.) nb and σ(pp → ZX) × B(Z → `+`−) = 0.974 ± 0.007 (stat.) ± 0.007 (syst.) ± 0.018 (th.) ± 0.039 (lumi.) nb, limited to the dilepton invariant mass range 60 to 120 GeV. The luminosity-independent cross section ratios are (σ(pp→WX)×B(W→ `ν)) / (σ(pp→ ZX)×B(Z→ `+`−)) = 10.54± 0.07 (stat.)± 0.08 (syst.)± 0.16 (th.) and (σ(pp→W+X)×B(W+ → `+ν)) / (σ(pp→W−X)×B(W− → `−ν)) = 1.421± 0.006 (stat.)± 0.014 (syst.)± 0.029 (th.). The measured values agree with next-to-next-to-leading order QCD cross section calculations based on recent parton distribution functions. Submitted to the Journal of High Energy Physics ∗See Appendix A for the list of collaboration members ar X iv :1 10 7. 47 89 v1 [ he pex ] 2 4 Ju l 2 01 176 paginas, 29 figuras, 20 tablas.-- Open Access: This article is distributed under the terms of the Creative Commons Attribution Noncommercial License.-- CMS Collaboration: et al.

Z

A bstractThe

Production Cross Sections in

\mathrm{t}\overline{\mathrm{t}}

pp

production cross section

Collisions at

\left( {{\sigma_{{\mathrm{t}\overline{\mathrm{t}}}}}} \right)

s=7

is measured in proton-proton collisions at