Professor Todd Huffman

Abstract:

We report a measurement of the time-dependent ratio of D0→K +π- to D0→K-π+ decay rates in D*+-tagged events using 1.0 fb-1 of integrated luminosity recorded by the LHCb experiment. We measure the mixing parameters x′2=(-0.9±1.3)×10-4, y′=(7.2±2.4)×10-3, and the ratio of doubly-Cabibbo-suppressed to Cabibbo-favored decay rates RD=(3. 52±0.15)×10-3, where the uncertainties include statistical and systematic sources. The result excludes the no-mixing hypothesis with a probability corresponding to 9.1 standard deviations and represents the first observation of D0-D̄0 oscillations from a single measurement. © 2013 CERN.

Abstract:

The fibres used for the readout of the upgraded LHC detectors for the High Luminosity Large Hadron Collider (HL-LHC) will be exposed to very high radiation doses of up to ∼ 500 kGy(Si). From DC measurements of the radiation induced absorption, several singlemode (SM) and multimode (MM) fibres have been qualified. The effect of radiation damage on fibres is also expected to have an adverse impact on the fibre bandwidth. This paper explains the theoretical reasons for this and presents results of extensive tests to determine the significance of this effect for one of the previously qualified radiation-hard multi-mode fibres. © 2012 IOP Publishing Ltd and Sissa Medialab srl.

Abstract:

© 2012 CERN. Published by Elsevier B.V. A search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector at the LHC is presented. The datasets used correspond to integrated luminosities of approximately 4.8 fb -1 collected at √s = 7 TeV in 2011 and 5.8 fb -1 at √s = 8 TeV in 2012. Individual searches in the channels H → ZZ(*) → 4l, H → γγ and H → WW(*) eνμν in the 8 TeV data are combined with previously published results of searches for H → ZZ (*) , WW (*) , bb and τ + τ - in the 7 TeV data and results from improved analyses of the H → ZZ(*) →4l and H → γγ channels in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of 126.0±0.4 (stat)±0.4 (sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7×10 -9 , is compatible with the production and decay of the Standard Model Higgs boson.