CDF Overview

Joseph Kroll

Penn DOE Review

6 August 2007

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

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

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

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

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

Conference Presentations by Penn People

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.

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

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.

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

_

___

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.

_

_

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.

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.

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)