Transcript Document

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!
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Physics in 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
• Presented as preliminary result in
Summer 2011:
• SM is safe on this front
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Physics in 2011
• 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 ET and 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)
Example: better c jet
identification to reduce
background
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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%
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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
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