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DØ and Hunting the Higgs at Arizona. Faculty: Erich Varnes Postdocs: Amitabha Das (departing in January for postdoc at SMU), Xiaowen Lei (joined in Summer 2011), Ruchika Nayyar (joined January 3) Students: Fionbarr O’Grady (half-time, joined in summer 2011)
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DØ and Hunting the Higgs at Arizona • Faculty: Erich Varnes • Postdocs: Amitabha Das (departing in January for postdoc at SMU), Xiaowen Lei (joined in Summer 2011), Ruchika Nayyar (joined January 3) • Students: Fionbarr O’Grady (half-time, joined in summer 2011) • Thanks to DOE for continued strong support of the DØ program!
Physics in 2011 • Presented as preliminary result in Summer 2011: • Completed top quark analyses • Measurement of W helicity fractions in top quark decays published in PRD • Working with CDF on Tevatron combination • Paper has been ~ready to go for some time, waiting for final approval from CDF • SM is safe on this front
Physics in 2011 Example: better c jet identification to reduce background • Transitioned to Higgs boson search (Varnes, Lei, O’Grady) • Looking in ZH nnbb channel, which is complementary to LHC search (and sensitive at low mass) • Contributions include: • Increasing signal acceptance (for WH) by improving sensitivity to spurious missing ETand expanding trigger menu • Updating analysis software to use newer data and Monte Carlo • Studies of optimal use of b ID information (both in terms of statistical and systematic uncertainty)
Physics in 2011 • Limit on Higgs production cross section from DØ in ZH nnbb shown at EPS’11: • Aiming for update at Moriond, followed by publication • Additional data + analysis improvements should increase sensitivity by ~30%
Service in 2011 • Varnes: DØ algorithms/physics coordinator • Preparation of new data reconstruction and MC versions • Coordinating selection of subset of data that is being reprocessed for “final” DØ results in summer 2012 • One of three nominees for spokesperson in 2011 election • Das: shifts, L1MU trigger expert, refined version of fake track discriminant • Lei: contributing to b ID studies • Focusing on introducing additional information into boosted decision tree used to classify jets • Preliminary estimate is ~5% improvement in b ID efficiency for the same background rejection • Nayyar: EM ID convener • Will oversee measurements of EM ID efficiency on reprocessed data