arXiv subjects

Douglas Orbaker

Publications and source records attributed to Douglas Orbaker.

3 recordsLinked to original sources

arXiv2015

Reconstructing top quark-antiquark events with one lost jet

We present a technique for reconstructing the kinematics of pair-produced top quarks that decay to a charged lepton, a neutrino and four final state quarks in the subset of events where only three jets are reconstructed. We present a figure of merit that allows for a fair comparison of reconstruction algorithms without requiring their calibration. The new reconstruction of events with only three jets is fully competitive with the full reconstruction typically used for four jet events.

hep-ex↗

arXiv2011

Measurement of the forward-backward asymmetry in top-antitop quark production in proton-antiproton collisions

We present a new measurement of the forward-backward asymmetry in ttbar production in ppbar collisions in the lepton+jets channel at D0. We measure asymmetries from two different observables and unfold the data to allow the results to be compared to standard model predictions. For the unfolded asymmetry based on the Delta-y variable, we measure (19.6 +/- 6.5)%, compared with an MC@NLO-based prediction of (5.0 +/- 0.1)%. We also discuss the correlation between the asymmetry and the transverse momentum of the ttbar system.

hep-ex↗

arXiv2010

Czochralski Silicon as a Detector Material for S-LHC Tracker Volumes

With an expected ten-fold increase in luminosity in S-LHC, the radiation environment in the tracker volumes will be considerably harsher for silicon-based detectors than the already harsh LHC environment. Since 2006, a group of CMS institutes, using a modified CMS DAQ system, has been exploring the use of Magnetic Czochralski silicon as a detector element for the strip tracker layers in S-LHC experiments. Both p+/n-/n+ and n+/p-/p+ sensors have been characterized, irradiated with proton and neutron sources, assembled into modules, and tested in a CERN beamline. There have been three beam studies to date and results from these suggest that both p+/n-/n+ and n+/p-/p+ Magnetic Czochralski silicon are sufficiently radiation hard for the $R>25$ cm regions of S-LHC tracker volumes. The group has also explored the use of forward biasing for heavily irradiated detectors, and although this mode requires sensor temperatures less than -50\,$^\circ$C, the charge collection efficiency appears to be promising.

physics.ins-det↗