cdf overview
DESCRIPTION
CDF Overview. Joseph Kroll Penn DOE Review 6 August 2007. TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: A A A A A A A. Faculty Joseph Kroll Nigel Lockyer (adjunct, not DOE) Evelyn Thomson Brig Williams Post-docs Anadi Canepa (not DOE) - PowerPoint PPT PresentationTRANSCRIPT
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CDF Overview
Joseph Kroll
Penn DOE Review
6 August 2007
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Personnel
• Faculty– Joseph Kroll
– Nigel Lockyer (adjunct, not DOE)
– Evelyn Thomson
– Brig Williams
• Post-docs– Anadi Canepa (not DOE)
– Aart Heijboer
– Chris Neu
• Graduate Students– Justin Keung (20% DOE)
– Elizabetta Pianori
– Tatiana Rodriguez
– Yanjun Tu
• Instrumentation Group– Joel Heinrich
– Walter Kononenko
Advances in people’s careers:Kristian Hahn: MIT post-docAafke Kraan: Marie Curie EU FellowshipDaniel Whiteson: Assistant Professor UC Irvine
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Contributions to CDF Experiment/Operations
• Major contributions of the past***– COT front end electronics - ASDQ ASIC & daughter board (Lockyer)
– TOF signal electronics (Jones, Oldeman, Chen, Usynin, Kroll)• Still carry TOF pager (Heijboer)
• Trigger Level 2 upgrade– Run IIa upgrade (Hahn, Neu, Whiteson, Kroll, Wittich)***
– Run IIb Calorimeter + general expertise (Canepa – see talk today)
• Calibration constants– 1st organized systematic calibration effort (Kraan)
– Set up automatic calibration procedure for production (Whiteson)
• Silicon tracking detector alignment (Heijboer)
***Critical contributions from Penn Instrumentation Specialists
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Physics
• B Physics (this talk)– Primary participants in B0
s flavor oscillations
• Top Physics (see talk by E. Thomson)– Top cross-section
– Top mass
– Top decay properties (W helicity measurement)
• SUSY (see talk by A. Canepa)– High mass dilepton pairs (e¹, e¿, ¹¿)
• Standard Model Higgs (this talk & Thomson, Canepa)– Contributions in several areas – see details later in this presentation
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Publications
Authors of 12 publications from CDF Run II in PRL or PRD including• 1st Tevatron Run II PRL (Charm cross-section, C. Chen thesis)• 1st Tevatron Run II High-pT PRL (top dilepton cross-section)
This past year we authored 5 publications
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Observation of B0s Oscillations
• Penn played major leadership role• Began in Run I
– Development of flavor tagging– B0 oscillation measurements– Sin2¯ analysis– TOF prototype
• Run II Highlights– TOF critical for observation– Co-leader of analysis (Kroll)– 1st measurement of excess of kaons
around B0s (Usynin)
– Proposed & executed method to determine significance (Heijboer)
– Critical innovations to sped up likelihood fit (Heijboer)
– Primary authors of both PRLs
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Conference Presentations by Penn People
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Plans for the Coming Year
Tevatron CDF and
are both running extremely well
The most exciting results are still to come from these data
CDF: > 2.6 fb-1
80% eff.
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Search for SM Higgs at Tevatron
Largest production cross-section
But QCD backgroundoverwhelms at low mass
H ! b¹b Instead search for
H ! W W (ZZ)
For low mass HiggsUse associated productionLeptonic W & Z easily identified
H ! b¹b
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Penn Contributions to Higgs Search
• New trigger capabilities (see talk by A. Canepa)– L2 upgrade – Studies of trigger algorithms (Higgs trigger task force, ¿ triggers)– Increase trigger efficiency – especially as inst. L increases
• Understand backgrounds (see talk by E. Thomson)– Measure Wbb cross-section (see talk by E. Thomson)– Measure WZ, ZZ production
• Increase signal sensitivity (see talk by E. Thomson)– Z! bb for b-jet energy calibration– b tagging studies
• Add new signal paths– Build on ¿ id developed for dilepton SUSY search (A. Canepa talk)
• Add W!¿º¿ to WH channel• Use W!¿º in H! WW
– Use W,Z! qq0 in WH, ZH (discussed here)• Exploit experience with Matrix Element tech. used in top mass meas.
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Motivation
V (= W or Z)
H
q
q
_
b
b_
All-hadronic channel has largest signalyield of all channels (Br W/Z ! qq ≈ 68%)Challenge: Large QCD bbqq backgroundRun I result was comparable with leptonicchannels: as good as Wl and Zl+l-
Not yet investigated in Tevatron Run II. Will add new events to ongoing searches.Data collected with multi-jet trigger originallyintended for all-hadronic ttbar.
CDF Run I PRL 95, 051801(2005)
Initiated by A. Heijboer + D. Whiteson. Joined upwith parallel initiative by group from AcademiaSinica (Taiwan).
qq=68%
ee
W decay modes
_qq=70%
ee
Z decay modes
_
___
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Modeling the QCD background
idea: look in background-enriched 1-b tagsample to estimate the number of 2-b tag signal events. Determine the Tag Rate Fraction (TRF) in a region without VH signal.Backgrounds with real Z/W (e.g. ttbar) will be modeled by MC
Mbb
Mqq
VHsignal
'signal' region
qq sideband: useto measure TRF
qq sideband: useto measure TRF
Mbb (GeV)
TRF predictiondata
Tag rate functionpredicts #eventsin signal region.
_
_
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Separating signal and background
particular for this analysis: O(100k) events to analyze. Execution speed had to be drastically improved (from 15 min ! 10 sec).S/B separation compares favorably to alternatives (NN, DBT)
data (QCD)Higgs signal MC
Discriminate between data and background using Likelihood computedusing Matrix Elements. The probability of seeing event x is:
matrix elementdescribes parton
level physics
integrate over unknown parton momenta
jet transfer functionsdescribes the detectorresponse to partons
QCD normalizedto signal MC
P(x|WH) + P(x|ZH)P(x|WH) + P(x|ZH) + P(x|QCD)
( )log
Likelihood ratio to discriminate signal and bg.
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Separating signal and background
particular for this analysis: O(100k) events to analyze. Execution speed had to be drastically improved (from 15 min ! 10 sec).S/B separation compares favorably to alternatives (NN, DBT)
Discriminate between data and background using Likelihood computedusing Matrix Elements. The probability of seeing event x is:
matrix elementdescribes parton
level physics
integrate over unknown parton momenta
jet transfer functionsdescribes the detectorresponse to partons
P(x|WH) + P(x|ZH)P(x|WH) + P(x|ZH) + P(x|QCD)
( )log
Likelihood ratio to discriminate signal and bg.
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Plan
First estimate of expected sensitivity expect limit around
sm=15 for low M
H
Comparable to other analysesGood prospect for adding significantlyto combined Tevatron limit.
Goal: Complete a ~2 fb-1 analysis by the end of the year.
Possible improvements:Add other trigger paths potentially factor ~2 more dataAnalyze events with 1 b-tagequivalent to adding ~50% statisticsUse advances b-tagging algorithmsAdd Vector Boson Fusion channel(initial studies being done by P. Methala, Univ. Helsinki).
exluded by LEP
sensitivity estimate for 1.7 fb-1
(no systematics included)