Accelerator Neutrinos

Abstract:

We present a search for a new heavy charged vector boson W′ decaying to an electron-neutrino pair in pp̄ collisions at a center-of-mass energy of 1.96 TeV. The data were collected with the CDF II detector and correspond to an integrated luminosity of 5.3fb-1. No significant excess above the standard model expectation is observed and we set upper limits on σ•B(W′→eν). Assuming standard model couplings to fermions and the neutrino from the W′ boson decay to be light, we exclude a W′ boson with mass less than 1.12TeV/c2 at the 95% confidence level. © 2011 American Physical Society.

Abstract:

We report on a search for new particles in the diphoton channel using a data sample of pp̄ collisions at √s=1.96TeV collected by the CDF II detector at the Fermilab Tevatron, with an integrated luminosity of 5.4fb⊃-1. The diphoton invariant mass spectrum of the data agrees well with the standard model expectation. We set upper limits on the production cross section times branching ratio for the Randall-Sundrum graviton, as a function of diphoton mass. We subsequently derive lower limits on the graviton mass of 459GeV/c2 and 963GeV/c2, at the 95% confidence level, for coupling parameters (k/M̄Pl) of 0.01 and 0.1, respectively. © 2011 American Physical Society.

Abstract:

Dijet angular distributions from the first LHC pp collisions at center-of-mass energy s=7 TeV have been measured with the ATLAS detector. The dataset used for this analysis represents an integrated luminosity of 3.1 pb-1. Dijet Χ distributions and centrality ratios have been measured up to dijet masses of 2.8 TeV, and found to be in good agreement with Standard Model predictions. Analysis of the λ distributions excludes quark contact interactions with a compositeness scale Χ below 3.4 TeV, at 95% confidence level, significantly exceeding previous limits. © 2010 CERN.

Abstract:

A search for new interactions and resonances produced in LHC proton-proton (pp) collisions at a centre-of-mass energy √s = 7 TeV was performed with the ATLAS detector. Using a dataset with an integrated luminosity of 36 pb -1, dijet mass and angular distributions were measured up to dijet masses of ∼3.5TeV and were found to be in good agreement with Standard Model predictions. This analysis sets limits at 95% CL on various models for new physics: an excited quark is excluded for mass between 0.60 and 2.64 TeV, an axigluon hypothesis is excluded for axigluon masses between 0.60 and 2.10 TeV and quantum black holes are excluded in models with six extra space-time dimensions for quantum gravity scales between 0.75 and 3.67 TeV. Production cross section limits as a function of dijet mass are set using a simplified Gaussian signal model to facilitate comparisons with other hypotheses. Analysis of the dijet angular distribution using a novel technique simultaneously employing the dijet mass excludes quark contact interactions with a compositeness scale A below 9.5 TeV. © 2011 CERN for the benefit of the ATLAS Collaboration.

Abstract:

A search for the Standard Model Higgs boson at the Large Hadron Collider (LHC) running at a centre-of-mass energy of 7 TeV is reported, based on a total integrated luminosity of up to 40 pb-1 collected by the ATLAS detector in 2010. Several Higgs boson decay channels: H→γγ, H→ZZ(*)→ℓℓℓℓ, H→ZZ→ℓℓνν, H→ZZ→ℓℓqq, H→WW(*)→ℓνℓν and H→WW→ℓνqq (ℓ is e, μ) are combined in a mass range from 110 GeV to 600 GeV. The highest sensitivity is achieved in the mass range between 160 GeV and 170 GeV, where the expected 95% CL exclusion sensitivity is at Higgs boson production cross sections 2. 3 times the Standard Model prediction. Upper limits on the cross section for its production are determined. Models with a fourth generation of heavy leptons and quarks with Standard Model-like couplings to the Higgs boson are also investigated and are excluded at 95% CL for a Higgs boson mass in the range from 140 GeV to 185 GeV. © 2011 CERN for the benefit of the ATLAS collaboration.