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trigger efficiencies for GMSB

trigger efficiencies for GMSB

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trigger efficiencies for GMSB

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  1. trigger efficiencies for GMSB Andrea Bangert Santa Cruz Institute for Particle Physics April 19th, 2010

  2. sample and selection cuts • sample: • GMSB1, sample 105410 • 10 TeV collisions (mc08) • reconstructed in 15.3.1.6 • ATLAS-GEO-02-01-00 • software: • svnweb.cern.ch/trac/atlasusr/browser/abangert/diphotonGMSB • run in athena 15.6.0 • selection cuts: • MET > 60 GeV • HT > 550 GeV, • two reconstructed photons • pT > 20 GeV • eta < 2.5 • isEM is tight • ET(ΔR < 0.2) / ET < 0.1

  3. cut flow • number of events remaining after each selection cut • no trigger • EF_g20_loose • requires one photon • pT > 20 GeV • EF_2g20_loose • requires two photons • pT > 20 GeV • initial efficiency of g20_loose is 97.8% • Efficiency after all cuts is 100% • initial efficiency of 2g20_loose is 78.5% • efficiency after all cuts is 99.6%

  4. pT of gravitino vs MET • every GMSB1 event produces two neutralini • each neutralino decays to produce gravitino and photon (or Z) • left: gravitino with highest pT, right: gravitino with lowest pT • gravitino with highest pT determines MET • subleading gravitino has less impact on MET

  5. pT of gravitino vs pT of photon • left: gravitino associated with photon with highest pT • right: gravitino associated with subleading photon • photon with highest pT is likely to be associated with subleading gravitino • gravitino with highest pT is likely to be associated with subleading photon

  6. trigger efficiency as function of photon pT • left: 2g20_loose (requires 2 photons), right: g20_loose (requires 1 photon) • caveat: no matching was done • between true photon from neutralino decay and object which fired trigger • one can see how the trigger turns on at pT = 20 GeV

  7. trigger efficiency vs photon pseudorapidity • left: 2g20_loose (requires 2 photons), right: g20_loose (requires 1 photon) • cut: pT > 20 GeV • caveat: no matching was done • one can see how the trigger turns on at η = 2.5

  8. trigger efficiency vs MET • Large MET indicates high pT for leading gravitino. • High pT for leading gravitino indicates lower pT for subleading photon. • Is this why efficiency of two photon trigger drops slightly as MET increases?

  9. trigger efficiency vs sum of ET sum of ET weak production strong production sum of ET in calorimeter clusters

  10. conclusion • good news • EF_g20_loose and EF_2g20_loose almost 100% efficient • for events which pass selection cuts • no prescale at L = 1031 1/cm2 s • 2g20 has no prescale at L = 1032 1/cm2 s • not so good: g20 has prescale of 10 at L = 1032 1/cm2 s • twiki.cern.ch/twiki/bin/view/Atlas/TriggerPhysicsMenu • caveat • model represents single point in GMSB phase space • goal • run over MC09 sample • in athena 15.6.7 • problem • trigger configuration dysfunctional in 15.6.7