CDF Results

Andrew Mehta

Liverpool Christmas Meeting 2008

2

Tevatron

Analyses in this talk use 0.9 - 2.7 fb-1 per experiment

•Tevatron is running really well:

Expect 6-8 fb-1 datasets by end of 2009 + possibly run in 2010

Andrew Mehta

Data analysed with 2 multipurpose detectors CDF and D0:

EM +had calorimeters for e +jet idMuon detectors

Silicon vertex detectors for b tagging

Lumi per experiment

3

The Challenge at to find new physics

Andrew Mehta

QCD jet production is huge. Must be understood before we can Investigate rare processes

4

QCD Z/γ+bjet

Photon

27/09/08 Andrew Mehta

Z

Photon agrees well with LO MCs. No NLO available yet. Publication soon (waiting forMC comparison for data at lower Et).

Z+bjet has NLO comparison. Better agreement obtained if we lower the scalein the calculation. Paper just submitted.

Sys. errors reducedIn publication

Tara Andy

5

Search for chargino-neutralino production in 3 lepton final states

Andrew Mehta

Paper published this year.

No signal found in this or other channels set limits e.g. for MSSM no-mix chargino mass<150

GeV is excluded

Giulia

6

Top /W Mass

Top mass is still a very active topic - 7 New results in 2008 from CDF

Andrew Mehta

172.4 ± 0.7(stat) ± 1.0(syst) GeV/c2

Summer CDF/D0 combination:

Already beat the Run II goal

Really want to improve W mass. No results yet but work going onVery difficult analysis!

7

Higgs Production at the Tevatron and DecayH

iggs

Pro

duct

ion C

ross

Sect

ion [

pb]

Hig

gs

Bra

nch

ing R

ati

o H

xx

WH lvbbZH llbb, vvbb

Main channels at low mH<140 GeV

Tevatron s=1.96 TeV

ttH

Andrew MehtaDominant gg H, H bb has massive background

Main channels at low mH>140 GeV

H WW

8

Higgs Tevatron Combination

Updated Tevatron Combination in progress!

- Status of April 9th 2008 -

Andrew Mehta

Summer 2008

Tevatron for the first time can exclude a Higgs at 95% CL,albeit with a tiny mass range.

Publication of channel we worked on (ZH, Z→ll,H→bb) this year+First use of H1 track+jet algorithm

Andy

9

Muon Event Paper

Andrew Mehta

CDF produced a paper investigating reconstructed muons with large impact parameters

Hint in paper is that these cannot be explained by SMprocesses.

Obvious SM explanations are in flight decays of K , Ks,π, punchthrough

These effects ‘account for half of the events but given the size of the uncertainty we cannot exclude that all events can be accounted for’ (paraphrased from paper)

Paper then looks at a sample of these ‘muons’ produced very close to an additional ‘muon’ (hadronic punchthrough?)

Study of multi-muon events produced in p-pbar collisions at sqrt(s)=1.96 TeV.By CDF Collaboration (T. Aaltonen et al.). FERMILAB-PUB-08-046-E, Oct 2008. 70pp. Submitted to Phys.Rev.D e-Print: arXiv:0810.5357 [hep-ex]

Liverpool and at least 1/3 of collaboration removed names from paper because:• We did not think analysis was complete. Many obvious checks not performed.

• Many internal results conflicted with results in paper.

• Many experts disagreed with statements in paper.

• Most calculations back of the envelope. No full simulation of jets comparison with data.

• Paper very badly written + organised in the chronological order of work done rather than in a logical order

• Paper has an undertone of new physics throughout, when most of us feel effects (if there are any) are due to detector, simulation or soft physics uncertainties

• Paper did not go through the usual CDF procedures

10

Muon Event Paper

Andrew Mehta

Will be interesting to see what external referee thinks

11

Summary

•Tevatron running well. Producing lots of data and lots of publications.

• Liverpool group is small but has still achieve a lot in the past year in QCD+ SUSY+Higgs searches

•Top mass now at very good precision. Hope for an improvement in the W mass soon

• Have excluded a SM Higgs mass for the first time

• Expect 2-3 times current analyzed lumi (more if we run in 2010)

Andrew Mehta

12

Summary of Analyses in low mass region

ChannelCDF

95% C.L. Limits BR/SM obs (exp)

D095% C.L. Limits BR /SM obs

(exp)

WHlbb (NN) 5.0 (5.8) 2.7fb-1 9.3 (8.5) 1.7fb-1

WHlbb (ME+BDT) 5.7 (5.6) 2.7fb-1

WHbb (NN) - 35.4 (42.1) 0.9fb-1

VHqqbb (ME) 37.0 (36.6) 2.0fb-1 -

ZHllbb (NN) 11.6 (11.8) 2.4fb-1 11.0 (12.3) 2.3fb-1

ZHllbb (ME) 14.2 (15.0) 2.0fb-1

ZHvv/WH (l) vbb (NN)

7.9 (6.3) 2.1fb-1 7.5 (8.4) 2.1fb-1

ttHlbbbbqq - 63.9 (45.3) 2.1fb-1

H - 30.8 (23.2) 2.7fb-1

H 30.5 (24.8) 2.2fb-1 -

Combined X.X (X.X) X.X (X.X)

mH=

115

GeV

/c2

(mH=120 GeV)

27/09/08 Andrew Mehta

Also WW contributes in the low mass region