CDF Results Andrew Mehta Liverpool Christmas Meeting 2008.
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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 id Muon 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 for MC comparison for data at lower Et). Z+bjet has NLO comparison. Better agreement obtained if we lower the scale in the calculation. Paper just submitted. Sys. errors reduced In 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/c 2 Summer CDF/D0 combination: Already beat the Run II goal Really want to improve W mass. No results yet but work going on Very difficult analysis!
7 Higgs Production at the Tevatron and Decay Higgs Production Cross Section [pb] Higgs Branching Ratio H xx WH lvbb ZH llbb, vvbb Main channels at low m H <140 GeV Tevatron s=1.96 TeV ttH Andrew Mehta Dominant gg H, H bb has massive background Main channels at low m H >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 SM processes. Obvious SM explanations are in flight decays of K, K s, 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]T. Aaltonen et al.
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 Channel CDF 95% C.L. Limits BR/SM obs (exp) D0 95% C.L. Limits BR /SM obs (exp) WH l bb (NN) 5.0 (5.8) 2.7fb -1 9.3 (8.5) 1.7fb -1 WH l bb (ME+BDT) 5.7 (5.6) 2.7fb -1 WH bb (NN) -35.4 (42.1) 0.9fb -1 VH qqbb (ME) 37.0 (36.6) 2.0fb -1 - ZH llbb (NN) 11.6 (11.8) 2.4fb -1 11.0 (12.3) 2.3fb -1 ZH llbb (ME) 14.2 (15.0) 2.0fb -1 ZH vv/WH (l) vbb (NN) 7.9 (6.3) 2.1fb -1 7.5 (8.4) 2.1fb -1 ttH l bbbbqq -63.9 (45.3) 2.1fb -1 H -30.8 (23.2) 2.7fb -1 H 30.5 (24.8) 2.2fb -1 - CombinedX.X (X.X) m H =115 GeV/c 2 (m H =120 GeV) 27/09/08 Andrew Mehta Also WW contributes in the low mass region