Report of our of Physics activities (update on status)

1. Report of our of Physics activities(update on status) Supreet Pal Singh Sunil Bansal (P.U.Chandigarh) (P.U.Chandigarh) Jasbir Singh Kajari Mazumdar (P.U.Chandigarh) (TIFR,Mumbai) India_CMS meeting, Delhi28.9.7

2. Our Channels • pp -> Z -> tt-> e+m+X. Priority item at present, though in all cases we need to learn how to pick up Electrons, muons, jets, MET, put proper corrections and so on. • Invisible Higgs in qq -> qqH. • Bs -> mmg • Joint effort by team members since various fronts have to tackled continuously to be in pace with developments at CERN. • Need to be continuously in touch with concerned people at CMS. • Regular presentations in meetings (slides in indico): ElectroWeak tau: …. , 6.7.7, 17.7.7, 27.8.7, 14.9.7, 28.9.7 Similarly in Higgs and B-physics

3. Preparation for CSA07 • Prepared cfg files for production of various signal and background events we are interested in. Needed to supply also various parameters, like efficiency of generation. • Alpgen events for W/Z +2,3 jets need special effort, generation of various files for each type done satisfactorily within deadline. • Twiki page edited accordingly. • Prepared skim (and other necessary) files for relevant channels, edited and tested many times according to changing whimzes of CMS management !!!! • Estimated skim sizes at various level, AOD, RECOSIM files etc. (including background events expected in concerned primary datasets). Sometimes it meant running jobs over Billions of events very quickly!

4. Update on Z -->tt-->e m • https://twiki.cern.ch/twiki/bin/view/CMS/EWKSkimAndAnalysesDuringCSA07 Typical info: • Data used: Spring07/preCSA07 Z  tt inclusive • Trigger eff. of L1 +HLT e+mu ( in CMSSW_160 = 0.42 %) • Event size (AODSIM or RECOSIM) • Configuration, skim files etc. linked. • To be updated continuously with recent developments, results. • We are responsible for editing relevant section. • For CSA07 each physics group could have a maximum of 5 or 6 skims • We use Xchannel trigger (both e & m).  our skimming has been shunted few times between electron and muon primary datasets!

5. Near Future of Z ->tt-->e m • 9 packages for EWK analysis: code for CSA07/2007/2008 EW analysis. • ElectroWeakAnalysis/ZTauTau_EMu code being put in CVS • Skeleton of analysis note: CMS AN 2007/xxx, October, 2007 (already exists in CVS!) Tau production from Z and W decays in pp collision at √s = 14 TeV KM (among total 13) responsible for writing relevant section of the note. • Our analysis will have to be reasonably finalised by early-October! (Analysis note will be submitted to CMS collaboration by mid-October) • Access of most files from CASTOR has been a main deterrant recently. • CMS will allow use of any available data processed with 131 or 152 and higher, mainly the note is to describe “how” we shall do things  created some confusion and causing delay in analysis due to switching of CMSSW versions.

6. Signal data is produced as inclusive decays of t s Backgrounds considered: W- W+e + m + X ( from inclusive W decays) tt  e + m + X (from inclusive top decays) QCD jetse + m + X (split into about 25 pt bins) Used mostly CRAB to access data. Analysed Spring07 data with CMSSW_131_patch after rereco (correction for electron). Recently available signal data in large statistics with CMSSW_160, under study. Local analysis on resulting root files. Final set of selection and plots yet to be made. CSA07 skimmed data is likely to be hosted in T2, Bari . Update on Z tt e + m + Xanalysis

7. New Development: Fast Simulation Studies • Full simulation plots match with fast simulation in CMSSW160 (FAMOS). • FAMOS has been used successfully to simulate large statistics and devise selection criteria. • Estimation of M(tt) with approximation for neutrinoscollinear with visible leptons. (requires event by event solution of two equations). • Preliminary study  Loss of statistics for sensible solutions . (requires leptons not to be back to back). • Visible mass (constructed from MET, P_m, P_e) is more efficient though peak is shifted on lower side.

8. Charactersitics of Z tt e + m + X events • Leptons in signal are not very hard  low trigger efficiency. • Signal has low hadronic activity in central region No. of jets in the event with Et > 20 GeV, |h| < 5 is much lower than backgrounds. • Missing Transverse energy is reasonably low in signal and QCD events compared to ttbar and WW processes. • Electron and Muon are mostly back to back in transverse plane. (affects reconstruction of Z-peak with collinear approximation of ns. • Visible mass is more efficient, but not peaked at Z resonance. • Invariant mass of e-m peaked at a lower value for signal.

9. Update on Invisible Higgs • CSA07 preparation: signal cfg, Alpgen activities, skim etc. • Total 6 skims in Higgs group, involving 10 people (including KM). • HLT study showed modification of VBF parameter threshold in dedicated trigger path increases signal efficiency significantly but does not increase background rate too much. • Modification went into CMSSW_160+. • Analysis of Signal samples hampered due to unavailability in Spring 07 sample. • Private production of large statitistics sample is neither practical and nor encouraged within Higgs group. • ttbar and QCD backgrounds are under study. • For CSA07, Signal data will be hosted by Wisconsin T2, courtesy S.Dasu. • Estimated skimmed data size (from QCD, ttbar,.. events) is acceptable.

10. Example of Alpgen paraphernalia! • https://twiki.cern.ch/twiki/bin/view/Main/AlpgenSummer07 Contains informations like: • W+Jets For VBFHiggsToInvisible • Jet Multiplicity : 2Jets exclusive (inclusive for 3 jets, MLM matching different) • x-section: 148.22 pb • UnweightingxMatching Efficiency: 2.5e-4 x 0.19 • Number of Events to request: 3065 Million • Number of Events expected in Output : 148k=1fb-1 (limit put by production group) • PS grid2 File : w2j.grid2 (links to actual locations) • input file: w2j_VBFHiggsToInv.input • cmsGenw2jet_VBFHiggsToInv_alpgen.cfg • cmsRunCSA07Higgs_w2jet_VBFHiggsToInv.cfg • User Source Codew2j_vbf_inv.f • Similarly for W + 3 jets, Z + 2 jets, Z+ 3jets and edited twiki page acc.ly.

11. Status of Bs →mmg Analysis • Help from Arun Nayak highly appreciated during initial months. • Prepared 4 cfg files (out of total 20) for productions in Spring07 and CSA07 . • Prepared and tested skim (team of 5 including KM) files for B-physics group. • New HLT condition and SKIM cannot be tested with signal at present. • Private production of Signal sample is going on. • Analysis in 160 to be improved to include muon id, (tracker muon), converted photons. • Code HLT selection to be integrated. • Can be tested mainly with QCD samples at present. • For low energy muons, muon-id is needed in CMSSW

12. Preliminary analysis in CMSSW160pre9, without HLT We would like to see the Bs peak above QCD background. We are palnning to study other control channels (decays of B-mesons with m and g in final state.) Eta distribution of all reconstructed photons (no matching) found skewed, reported, told to be known in CMS. This distribution is only from a subsample of QCD dijets with pt bin 170-230 GeV

13. Conclusions • CSA07: lot of uncertainties for many things, plans are evolving still. • 7 Primary Datasets, based on combination of HLT paths. 46+ physics skims, to be run at Tier1 s. • Analysis from Tier2. • Details physics streaming /skimming plans during CSA07 are fn.s of time! • Deadlines have been met for preparation of CSA07. Hope we shall be able to do physics with relevant datasets: • EWK Dielectron :150 GB • Bphysics onia: 1000 GB • Higgs vbf_jets + MET: 100 GB • We badly needed our T2. Analysis note on Tau should come up in time.

14. Back up Electron pT Z tt e +m +X FAMOS tte + m + X QCD jets e + m + X

15. Z e m ttbar  e m WW  e m ttbar  e m