CDF UK Aidan Robson PPGP: 22 April 2009 Glasgow Liverpool Oxford UCL

CDF UK

Aidan RobsonPPGP: 22 April 2009

GlasgowLiverpool

OxfordUCL

2/18CDF UK, PPGP 2009

Tevatron Performance

6 fb-1

delivered

5 fb-1 good datarecorded by CDF

3.6 fb-1 included in winter conferenceanalyses

2010 running is confirmed

2011 runningis being bid for

With 2 more years running: double delivered luminosity treble amount of good data currently analysed


Detector

CDF

– 2007 silicon cooling problems fixed– Expect to deplete silicon for life of experiment– Successful trigger upgrades addressed high trigger deadtimes at high instantaneous luminosity

Trigger coordination

Level3 trigger software

Calibration coordination

Calorimeter reconstructionTrack reconstruction

Offline infrastructureData-handlingGrid computing

L1 Trigger

L2 Trigger

L3 Trigger

OfflineReconstruction

DataHandling

SimulationSilicon L00

Detector performing well

UK involvement


UK Roles in CDF

OperationalAssociate Head of Detector OperationsCo-Head of OfflineLevel3 trigger software coordinationOffline calibration database coordinationCalorimeter reconstruction leaderTracking reconstruction leaderTrigger operations coordination (2007-8)Trigger and Dataset group leader (2006-7)Offline Operations manager (2006)

Roles since 2006. All current unless noted.

PhysicsElectroweak Physics co-convener x3Exotic Physics co-convener (2007-8)Subgroup conveners: W mass and width x3 W/Z analysis H->WW analysis (2006-8) Diboson analysis B mixing and lifetimes

CollaborationInternational finance committeeChair, Spokespersons election committeeSpokespersons’ paper reading groupStatistics committeeSpeakers committee (2006-7)

Student training9 PhD theses submitted in last 3 years


CDF UK Physics landscape

s(W+jets)PRD77(2008)052002s(W+charm)PRL100(2008)091803s(tt) (soft lepton tag)PRD-RC in review

s(g+b)s(Z+b)PRD79(2009)052008

mW

PRL99(2007)151801PRD77(2008)112001 GW

PRL100(2008)071801

mt (soft lepton tag)PRD-RC in review

mt (matrix element)PRD-RC in prep.

Bs oscillationPRL97(2006)062003B lifetimes

s(exclusive gg)PRL99(2007)242002s(exclusive ee)PRL98(2007)112001s(exclusive Z)PRL submitted

H->WWPRL102(2009)021802ZH->llbbPRL101(2008)251803Z'->eePRL99(2007)171802Z'->mmPRL102(2009)091805Z'->ggPRL99(2007)171801excited muonsPRL97(2006)191802trileptonsPRL99(2007)191806

rare decaysPRD79(2009)011104(R)

Benchmark measurements

Precision measurements

Flavour physics

Searches

Advanced tools building on earlier fundamentals Soft lepton tagging H1 jet algorithm

Unbiased B lifetime method from displaced vertex triggers

UK topicssince 2006

Total CDF PRLs/PRDs2006: 42 2008: 532007: 40 2009 so far: 29


mW, GW

Detector calibration: few 1/10000 in pT and ET

Detailed description of hadronic W production, decay and interaction with detector

Mass extracted from fits to mT, pT and ET from W->en and W->mn

Tevatron mW average now better than LEP average

mW = 80413 ± 48 MeV/c2

GW = 2032 ± 73 (stat+sys) MeV/c2

mmm / GeV E/p (W e➝ n)

200 pb–1

mT / GeV


mt

(1) Matrix element method, lepton + jets channel.PDF per event using signal (tt) and bck (W+jets) MEslikelihood function maximised wrt top mass, JES correction , and signal fraction mt = 172.4 ± 1.4 (stat+JES) ± 1.3 (sys) GeV/c2

= 172.4 ± 1.9 (total) GeV/c2

(2) Partially reconstructed invariant mass in soft muon b-tagged events (soft muon plus lepton from W decay)Minimal dependence on precision jet-energy calibration or precision vertex tracking. mt=181.3 ± 12.4(stat) ± 3.5(sys) GeV/c2

Current CDF combination:mt=172.6 ± 0.9(stat) ± 1.2(sys) GeV/c2


Exclusive processes

Require no (extra) tracks and empty calorimeters and bunch shower countersObserve 3 candidate pp->pggp events in 0.5pb-1 Observe 8 candidate pp->pllp events in 2fb-1 (0 pass the Z selection) (pppllp) = 0.24+0.13-0.10 pb [mll>40 GeV, |l|<4]

(Zexcl) < 0.96 pb at 95% CL

s ~ 0.3 fb; signal would be BSM

[cf LPAIR = 0.256 pb](pppggp) = 0.014+0.14-0.03 (stat) ± 0.03 (sys) pb

[ET>5 GeV, ||<1]theor: 0.04-0.2pb (Durham)


Rare decaysB+ -> mmK+

B0 -> mmK*Bs -> mmf

s

b

s

s

m+ m-

s

b

s

s

m+ m-

Never seen in a hadron collider

Never seen before

predicted BR(Bs->mmf) = 16.1x10-7

BRs measured relative to normalisation modes:

Penguin or box processes in the Standard ModelNew physics can exist in the loops (BR, kinematics)

relative efficiency from MC

)/()/(

)( /

/

−+Ψ

Ψ

−+

→=→→ μμψ

εε

ψμμ

μμ

μμ JBRNN

hJBBRhBBR

totalh

totalhJ

hJ

h

Count rare mode candidatesCount control mode candidates

B+mmK+ Abs BR (0.60±0.15±0.04)x10-6

4.5s observation

B0mmK* Abs BR

(0.82±0.31±0.10)x10-6

Bsmmf Rel BR 95% CL Limit

< 2.61x10-3

2m(mmK*) / GeV/c2 m(mmf) / GeV/c2


Z’ and RS searches

high mass mmm dominated by track curvature resolutionsignal templates constructed for 1/mmm distribution

search for excess using p-value scan of mass spectrum

mZ’(SM) > 1030 GeV/c2 at 95% CL

mZ’ / TeV/c2m–1mm / c2/TeV

mee / GeV/c2 mee / GeV/c2


Higgs searches

(1) ZH->llbbFind Z->ll + >=2 jets with >=1 b-tag2D Neural Net discriminant

q

q’

W,Z

H

(2) H->WW->lnln using neural networkssplit into 0,1,2+ jet binslow and high s/b dilepton combinations

CDF H->WW analysis only All CDF+D0 Higgs analyses

s < 1.45sSM at 95%CL (mH=165GeV/c2)

95%

CL

/ s SM

mH (GeV/c2)

NN outputCode to LHC!


CDF UK plans

The Standard ModelSearch

forH->WW

Precisionmeasurement

of mW

Confirmationof anomalous

bs


CP violation in Bs->J/y f

Bs mixing frequency well-measuredPhase of mixing amplitude also required to constrain NP

Large bs unequivocal sign of new physicsCDF and D0 see ~2s effects; CDF favours bs~0.8B factories see ~5s effects in b->s transitions

We are working on particle ID to improve measurement8 fb–1 would enable 5s observation of SM-violating bs

bs ~ 0.02 (SM)


mWCurrent CDF mW = 80413 ± 48 MeV/c2. Working on measurement with x12 data.

published (200pb-1)

expected (2.3fb-1)

DmWstat

(m)54 MeV 16 MeV

DmWstat (e) 48 MeV 14 MeV

DmWscale 20 MeV 6 MeV

Aiming for 25 MeV/c2 measurement

contains blinded offset

Measurement well underway;Requires years of work by dedicated team

Inst. L < 70x1030 s–1cm–2

c2/dof = 62/50

Inst. L > 70x1030 s–1cm–2

c2/dof = 41/50

DmZstat = 12 MeV/c2

c2/dof = 27/29


Higgs

Mar 07

Aug 07Feb 08

Oct 05

Jan 07

1.45

Aug 08

Expected limits

Developmentof sensitivity

in H->WW

Feb 09


Higgs

2s 3s

’

H->WW already most sensitive channel down to ~125 GeV/c2.Work on optimising at low mass.

Better harness characteristic VBF Higgs kinematics to improve sensitivity, and look for VBF W and Z production

Prob

abili

ty o

f 2 s

Exce

ss

Prob

abili

ty o

f 3 s

Evid

ence

With 10fb–1 have good chance of 2s evidence (or conversely 95% CL exclusion)of SM Higgs over the whole mass range – before LHC experiments have results

95%

CL

Lim

it /

SM

L=10 fb–1

w/ improvements

L=5 fb–1

w/ improvements


Request

We request minimal funding to complete exploitation: – common fund and M&O (~£100k) – travel funding (~£100k)

70% of CDF-UK effort dedicated to physics exploitationMost effort is from academics, plus Royal Society / STFC fellowship awardsCurrently only 0.5FTE committed RA rolling grant effort for CDF – Request for ½ an additional RA for Higgs search


Summary

The Tevatron is performing extremely well

UK physicists have produced a raft of world-leading physics results at CDF

Our ongoing analyses will remain competitive until the LHC experiments have collected substantial good data

We should make the most of our investment in CDF by completing our measurement of mW and continuing to improve our Higgs search.


Backup


CDF UK Personnel


A physics programme

During last 18 months

Heading towards Higgs

s (ppZZ) 3 s (ppH)(mH=160)

UK authors (pre-2006)


e+

e–

Z

H

Z b

bmH>114GeV mH<154GeV

Higgs mass ‘bounds’


EWK fits

Higgs mass from individual measurements pulls


q

q’

W,Z

H ’

Br

mH/GeV

BrWW

Production

Decays / fb

mH/GeV

ggH

qqWH

qqqqH

qqZHbbH

gg,qqttH


H0W+

l+

n

W–l–

n

ee, em, mm ; ET

Isolation

mll > 16

Z and topsuppression

Dilepton sample composition

Drel

l-Yan

dom

inat

edW

W d

omin

ated

Higg

s enh

ance

d

B

Z Z

tt ttWW WW WW WW

H H HH

signalseparation

H0W+

l+

n

W–l–

n

W+

W–

q

q’

q

q’

90%

10%

HWW


H

W–

W+

l –

l+

nn

NNscore

0 1

var1

var2var n

Spin structure WW vs HWW lepton Df

Cut-based analysis

Neural net approach

Looking for single final distinguishing distribution to which to fit templates for signal and background

extend sensitivity

Background Higgs

Analysis technique


NNscore

0 1

var1

var2var n Background Higgs

¨ Use Monte Carlo simulation ¨ Apply preselection (eg ET to remove Z/γ* )¨ Train on backgrounds against Higgs mH=110,120…160…200 { variations: can separate ee,em, }mm

one for each mH

¨ Pass signal/all backgrounds through net¨ Form templates for each background, add up

NN0 1

Pass templates and data to fitter

ET

SET

mll

Elep1

Elep2

ETsig

Probabilities from leading-order matrixelements

DataHWW

WWDY

WgWZZZt t

fakes

ETjet1

DRleptons

Dfleptons

Df ET lep or jet

ETjet2

Njets

Neural net method

0 10 10 1

0 10 1

Summed in proportion

…


Matrix element method

Use LO matrix element (MCFM) to compute event probability

HWWlnlnWWlnlnZZllnnW+partonln+jetWgln+g

ET modellepton energy resn

px

py

pz

lep1

LO |M|2 :px

py

pz

lep2

Ex , Eyparton lepton fake rateg conversion rate

xobs:

(with true values y)

Compute likelihood ratio discriminator

R =Ps

Ps + SkbiPb

i

i

kb is relative fraction of expected background contrib.Ps computed for each mH

Fit templates (separately for high S/B and low S/B dilepton types)


Limit setting

Aidan Robson Glasgow University

Isolation

mll > 16 or 25Z and topsuppressionsignalseparation

Background

Higgs signal x 10

even

ts

XX = some observable

H1=SM+Higgs (of mass mH)H0=SM only

Construct test statistic Q = P(data|H1)/P(data|H0) –2lnQ = c2(data|H1) – c2(data|H0) , marginalized over nuisance params except s H

Find 95th percentile of resulting s H distribution – this is 95% CL upper limit.

When computed with collider data this is the “observed limit”

Repeat for pseudoexperiments drawn from expected distributions to build up expected outcomes

Median of expected outcomes is “expected limit”E

xpec

ted

outc

omes

95% CL Limit/SM

Median = expected limit

sH (pb)

95%

sH/sSM

95%

0 20 1 2

rescalePDF


Background

Higgs signal x 10

even

ts

NN output scoresH (pb)

95%

0 1 2

PDF

sH/sSM

95%

0 2

rescale

Q = P(data|H1)/P(data|H0)

H1=SM+Higgs (of mass mH)H0=SM only

95%

CL

Lim

it /

SM

mH / GeV

median1s2s

illustrative

mH=160

Expe

cted

Out

com

es

Limit setting

expected limits

median


95%

CL

Lim

it /

SM

mH / GeV mH / GeV

expected limitobserved limit

illustrative

expected limitobserved limit

illustrative

Deficit Excess

Interpretation


CDF

h = 1.0

h = 0.6

h = 2.0muonchambersh =

2h = 3

0 1 2 3 m

2

1

0

tracker had cal

hadronic calEM cal

had cal

solenoid

pre-radiator shower max

silicon

EM cal

h = 1

Drift chamber to |h|<1Further tracking from SiCalorimeter to |h|<3Muon system to |h|<1.5

Documents

CDF UK Aidan Robson PPGP: 22 April 2009 Glasgow Liverpool Oxford UCL