Study of pp γ +N Jets Channel in CMS S. Bhattacharya, B.C. Choudhary, Pooja Gupta University of...

Study of pp γ +N Jets Channel in

CMSS. Bhattacharya, B.C. Choudhary, Pooja Gupta

University of Delhi, India

Poona Gupta India-CMS Meeting BARC, Mumbai 2

OUTLINE Updates on Gamma + Jet work Gamma + N jets Work done at CERN Progress Future plans


Updates on Gamma + Jet work Presented as poster in

XXVII Physics in Collisions held at Annecy, France from 26th June 2007 to 29th June 2007.

Selected for Oral talk. A 15 minute presentation was given at the conference.

The poster was also selected for a prize.

This work has been accepted for poster presentation in Lepton-Photon 2007 to be held at Daegu, Korea.


Gamma + N jetsMotivation In Continuation of previous work - Gamma + Jet using Pythia MC

and OSCAR and ORCA for simulation & reconstruction – CMS NOTE 2007/004.

Measurement of differential cross-section from the first data collection at the LHC.

Event Generation Use Alpgen version 2.12 a Leading Order Generator for Event

Generation. We are planning to generate Gamma + 1 jet, Gamma+ 2 jet,

Gamma + 3 jet exclusive (i.e, Jet-parton matching) and Gamma + 4 jet inclusive samples.

The proposal for Gamma + N jets events has been approved. Poona Gupta is responsible for providing the .cfg files and .grid2

files to the generator group.


Work done at CERN

Dear colleagues,

Poona was so kind to dig into the Alpgen production of photon+jets samples andafter consulting with M. Mangano, Filip and me has put together the following proposal. If anyone else is interested in similar samples: Please have a look at the parameters and let us knowwether or not they are fine for you. Filip, Poona and Klaus

Here are the few points regarding the proposal. Please have a look. We are interested in generating Gamma + N jets sample where N =1, 2, 3 , 4.1. The Gamma + 1 jet, 2jet and 3 jet would be exclusive samples and gamma + 4 jet would be inclusive sample.2. We are planning to modify the user routine in Phjetwork directory to do the Pt gamma binning as per the suggestions of M. Mangano. We are currently modifying the code and checking it.3. The kinematical parameters for the input file would be :nph 1njets 1 (1, 2, 3, 4 for different samples)ptjmin 20 (Default is 20 GeV)ptphmin 60 (Default is 20 GeV)etajmax 5.0etaphmax 2.7drjmin 0.7drphjmin 0.7

We are interested in HLT photons hence the ptphmin is taken as 60 GeV.4. The Pt gamma bins for each gamma + n jet sample would be : 60-120, 120-180, 180-240, 240-300, 300upHence there would be 20 bins in total.5. A minimum of 100 K events in each bin is required. That would sum upto 2-2.5 million events in total.

Proposal for Event Generation


Work done at CERN Develop Skims which would be a part of QCDAnalysis Package:

*** Discussion title: QCD Physics

Hello Olga, Natalia and Filippo,

you have all been added now as well as Poona Gupta andSushil Chauhan. Concerning photon skims it would be a good idea to establish contact to Vladimir and Toyoka resp. Poona and Sushil if not done yet.

Ciao, Klaus


Gamma + 1 Jet

PTγ

Min (Gev)

PTjet

min (GeV)

PTγ

bin(GeV)

No. of weighted events

Weighting efficiency

Cross-sec (pb)

No. of unweighted

events

Unweighting

Efficiency

Matching Efficiency

20 20 20 - 60 4229320 0.423 9.42E+04 1016765 0.240 0.680

60 20 60 - 120 4909948 0.491 2.75E+03 1078733 0.220 0.583

120 20 120 - 180 4248094 0.425 2.16E+02 1014495 0.239 0.449

180 20 180 - 240 4600044 0.460 4.18E+01 1031182 0.224 0.393

240 20 240 - 300 5467754 0.547 1.20E+01 979540 0.179 0.328

300 20 300up 5434798 0.543 7.81E+00 1332108 0.245 0.276

Gamma + 1 Jet Exclusive

N warm up : 8M Iterations : 6

N Events : 10M


Gamma + 2 Jets

PTγ

Min (GeV)

PTjet

min (GeV)

PTγ

Bin (GeV) No. of

weighted events


Cross-sec (pb)

No. of unweighted

events

Unweighting

Efficiency

MatchingEfficiency

20 20 20 - 60 84568 0.008 2.39E+04 36913 0.436 0.474

60 20 60 - 120 265898 0.027 2.77E+03 31942 0.120 0.400

120 20 120 - 180 113829 0.011 3.04E+02 34320 0.302 0.323

180 20 180 - 240 158237 0.016 6.76E+01 103625 0.655 0.282

240 20 240 - 300 187083 0.019 2.11E+01 89251 0.477 0.227

300 20 300up 167177 0.017 1.52E+01 24895 0.149 0.208



N Events : 10M


Gamma + 3 Jets

PTγ

Min (GeV)

PTjet

min (GeV)

PTγ

Bin (GeV) No. of

weighted events


Cross-sec (pb)

No. of unweighted

events

Unweighting

Efficiency

MatchingEfficiency

20 20 20 - 60 154812 0.015 1.00E+04 15429 0.100 0.293

60 20 60 - 120 228044 0.023 1.67E+03 27747 0.122 0.253

120 20 120 - 180 250887 0.025 2.64E+02 27234 0.109 0.229

180 20 180 - 240 106677 0.011 6.85E+01 23225 0.218 0.193

240 20 240 - 300 145555 0.015 2.32E+01 21259 0.146 0.171

300 20 300up 119386 0.012 1.85E+01 23991 0.201 0.149



N Events : 10M


Gamma + 4 Jets

PTγ

Min (GeV)

PTjet

min (GeV)

PTγ

Bin (GeV) No. of

weighted events


Cross-sec (pb)

No. of unweighted events

Unweighting

Efficiency

MatchingEfficiency

20 20 20 - 60 102495 0.007 1.70E+03 11840 0.116 1.000

60 20 60 - 120 152786 0.010 3.40E+02 18117 0.119 1.000

120 20 120 - 180 190279 0.013 6.11E+01 22161 0.116 1.000

180 20 180 - 240 157723 0.011 1.66E+01 21921 0.139 1.000

240 20 240 - 300 159525 0.011 5.75E+00 22803 0.143 1.000

300 20 300up 73668 0.005 4.50E+00 21687 0.294 1.000

Gamma + 4 Jet Inclusive


N Events : 15M


Matched Cross-sections

Matched Cross-sections (pb)

Pt Gamma BinGamma + 1 jet

(Exclusive)Gamma + 2 jets

(Exclusive)Gamma + 3jets

(Exclusive)Gamma + 4 jets

(Inclusive)

20 - 60 64061.9 11354.2 2939.2 1700.9

60 - 120 1603.0 1109.9 423.4 340.0

120 - 180 96.7 98.2 60.3 61.1

180 - 240 16.4 19.1 13.2 16.6

240 - 300 3.9 4.8 4.0 5.7

300up 2.2 3.2 2.8 4.5

This information is also available on the twiki page:

https://twiki.cern.ch/twiki/bin/view/CMS/Alpgen-photon-nJets


Summary and Future Plans Develop expertise in CMSSW.

The analysis script is being written. Prepare Skims and check them. Wait for the simulated data. Request for EM enriched multi-jet background events has

been made. Waiting for the approval.

Backup Slides


Why Jet Parton Matching?

Michelangelo Mangano, Lund University, Oct 7 2004

Study of pp γ +N Jets Channel in CMS S. Bhattacharya, B.C. Choudhary, Pooja Gupta University of...

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