2011 analysis :2011 analysis :Plans for Wgamma and Plans for Wgamma and ZgammaZgamma  

Zhijun Liang

Introduction 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)

Possible Roadmap to PLHC 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

Reminder of anomalous Reminder of anomalous triple gauge coupling(ATGC) 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.

Reminder of anomalous Reminder of anomalous triple gauge coupling (ATGC) triple gauge coupling (ATGC)

Assume all CP odd quantity is zero for nowShould 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 ?

ATGC in Zgamma channel 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

Radiation zero 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.

MC generation plan 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 ?)

Man power issue 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