Accelerator Neutrinos

Abstract:

In early 2010, the Long-Baseline Neutrino Experiment (LBNE) science collaboration initiated a study to investigate the physics potential of the experiment with a broad set of different beam, near- and far-detector configurations. Nine initial topics were identified as scientific areas that motivate construction of a long-baseline neutrino experiment with a very large far detector. We summarize the scientific justification for each topic and the estimated performance for a set of far detector reference configurations. We report also on a study of optimized beam parameters and the physics capability of proposed Near Detector configurations. This document was presented to the collaboration in fall 2010 and updated with minor modifications in early 2011.

Abstract:

We present a search for new physics in events with two high pT leptons of the same electric charge, using data with an integrated luminosity of 6.1fb-1. The observed data are consistent with standard model predictions. We set 95% C.L. lower limits on the mass of doubly charged scalars decaying to like-sign dileptons, mH±±>190-245GeV/ c2, assuming 100% BR to ee, μμ or eμ. © 2011 American Physical Society.

Abstract:

A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy √s=1.96TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of tt̄ pairs that decay into the lepton+jets channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parametrized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and a correction to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction (ΔJES) amounts to an additional in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using the data sample of 578 lepton+jets candidate events, corresponding to 3.2fb-1 of integrated luminosity, the top-quark mass is measured to be mt=172.4±1.4(stat+ΔJES)±1. 3(syst)GeV/c2. © 2011 American Physical Society.

Abstract:

This paper reports a search for nonstandard model topquark resonances, Z′, decaying to tt̄→W+bW -b̄, where both W decay to quarks. We examine the top-antitop quark invariant mass spectrum for the presence of narrow resonant states. The search uses a data sample of pp̄ collisions at a center of mass energy of 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron, with an integrated luminosity of 2.8fb-1. No evidence for top-antitop quark resonant production is found. We place upper limits on the production cross section times branching ratio for a specific topcolor assisted technicolor model in which the Z′ has a width of Γ Z′=0.012MZ′. Within this model, we exclude a Z′ boson with masses below 805GeV/c2 at the 95% confidence level. © 2011 American Physical Society.

Abstract:

We report constraints on antineutrino oscillation parameters that were obtained by using the two MINOS detectors to measure the 7% muon antineutrino component of the NuMI neutrino beam. In the Far Detector, we select 130 events in the charged-current muon antineutrino sample, compared to a prediction of 136.4±11.7(stat)-8.9+10.2(syst) events under the assumption |Δm̄2|=2.32×10-3eV2, sin2(2θ̄)=1.0. Assuming no oscillations occur at the Near Detector baseline, a fit to the two-flavor oscillation approximation constrains |Δm̄2|<3.37×10-3eV2 at the 90% confidence level with sin2(2θ̄)=1.0. © 2011 American Physical Society.