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2011 analysis : Plans for Wgamma and Zgamma

2011 analysis : Plans for Wgamma and Zgamma. Zhijun Liang. Introduction. Possible plan for this summer for SM W/Z+gamma: PLHC workshop (about 50~100pb-1): Update on SM W/Z+gamma cross section first TGC limit measurement on both W/Z+gamma EPS conference:

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2011 analysis : Plans for Wgamma and Zgamma

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  1. 2011 analysis :Plans for Wgamma and Zgamma Zhijun Liang

  2. Introduction • Possible plan for this summer for SM W/Z+gamma: • PLHC workshop (about 50~100pb-1): • Update on SM W/Z+gamma cross section • first TGC limit measurement on both W/Z+gamma • EPS conference: • As We discussed with SM EW convener that we should aim for EPS conference this summer ( about 100~200pb-1). • Topic: • Update on Cross section measurement with 5% level precision. • Observation of Radiation zero in W+gamma • First limit on ATGC coupling • Lepton/Photon conference: • Depend on how far we can go for EPS conference • Mainly focus on “Observation of Radiation zero in W+gamma” , hopefully we can reach 5 sigma in August with (500 pb-1)

  3. Possible Roadmap to PLHC • April 11~April 17: • complete the MC request for rel 16.6 • Develop and agree on the details on ATGC measurement • April 18~April 24 : • MC closure test for the method for ATGC limit measurement • Test the method on data 2010 • April 25~April 30 : • Complete the cutflow for 2011 data. • Complete photon efficiency background estimation on 2011 data • May 1~May 8 : • Final check on cross section measurement • Expect efficiency scale factor from performance • Set limit on ATGC coupling parameter using 2011 data. • May 8~May 15 : • Write up the COM/CONF note, SM approval

  4. Reminder of anomalous triple gauge coupling(ATGC) • ATGC is Related to W-W-gamma coupling vertex. • Any deviation from SM model end up with longer tails in photon pT spectrum.

  5. Reminder of anomalous triple gauge coupling (ATGC) • Assume all CP odd quantity is zero for now • Should we consider CP odd coupling limit for the late summer analysis, by constructing some CP odd observable? • Since any deviation from SM model breaks unitarity in high mass region, need to choice a form factor to converse unitarity in limit setting. • Which form factor function and parameter should we use ?

  6. ATGC in Zgamma channel • Similar to Wgamma TGC measurement, but one special channel need to be taken care. • Zγ->ννγ channel should have the best sensitivity. • Need to take care the photon trigger efficiency and MET/jet clean up cuts

  7. Radiation zero • Expect a dip angular distribution between lepton and photon in SM LO prediction. • And this cancellation between s,t,u channel of Wgamma is not straight forward to see according to gauge structure of SM model. • No 5 sigma confirmation from experiment before. • Latest D0 result reported 2.6 sigma significance to observe radiation zero effect.

  8. MC generation plan • Signal MC: • W/Z+gamma + 0jet/1jet/2jet/3jet • Madgraph, pT(gamma)>10GeV. • Signal MC with ATGC coupling: • W/Z+gamma+ 0jet • Baur generator, pT(gamma)>10GeV • Discussion : • 6% acceptance for previous analysis • Is that too low , shall we generate events with harder cuts ? • What is photon pT threshold ? • How many events do we need ?(500k enough ?)

  9. Man power issue • Need more help from all analysis group members, especially from new comers. • Open fields: • Develop and finalize the method for ATGC coupling measurement • Develop and optimize the cuts for radiation zero discovery. • Study jet multiplicities in W/Z+gamma events, optimize the jet veto cut for ATGC and RAZ study. • Photon identification efficiency and isolation efficiency in each pt/eta bins( possible to have 3 people to work on that ?) • Fudge MC methods • Electron extraploation • using pure photon from Z->μμγ • Photon trigger efficiency for Zγ ATGC study

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