Two Issues on Resolution

Bertrand, LiwenDec.16 ,2010

• Some problem of fitting invariant mass still exists

• Some results on special mc production with single photons

Selection of photon candidates

• ph_pt (leading) > 40 GeV, ph_pt (sub-leading) > 25 GeV• Robust tight photons (for both leading and subleading photon)

• ph_trackIsol < 4 GeV (for both leading and subleading photon)

• ph_EtCone40_corrected < 3GeV

Use: mc09_7TeV.106384.PythiaH120gamgam.merge.AOD.e505_s765_s767_r1430_r1429

Correction on photon energy

Comparison of invariant mass reslution

The default one after smearingare not fitted well

Comparison of invariant mass reslution

• Divided into three cases: unconverted photon + unconverted photon unconverted photon + converted photon converted photon + converted photon

unconverted photon + unconverted photon

With smearing

frac : the ratio of crystal ballAlpha, cbmean, cbsigma, n : parameters of crystal ballSigmean, sigwidth : parameters of gaussin

The plots of unconverted +unconverted before smearingis not well fittedDouble guassian

unconverted photon + converted photon

With smearing

frac : the ratio of crystal ballAlpha, cbmean, cbsigma, n : parameters of crystal ballSigmean, sigwidth : parameters of gaussin

converted photon + converted photon

With smearing

frac : the ratio of crystal ballAlpha, cbmean, cbsigma, n : parameters of crystal ballSigmean, sigwidth : parameters of gaussin

Some results on special mc production with single photons

MC:mc10_7TeV.107549.singlepart_gamma_E59p5_eta0p3.recon.AOD.e643_s933_s946_r1657mc10_7TeV.107581.singlepart_gamma_E60p0_eta1p7.merge.AOD.e643_s933_s946_r1657_r1700

dE distribution after some correctiondE=Erec - Etruth

(fixed eta=0.3 and E=59.5GeV)

Correlation among ID variables

eta=0.3 E = 59.5GeV

eta=1.7 E = 60 GeV

Next to do

• Correlation among ID variables• Define new ID variables• Work on more ready MC (fixed eta and E at different value)

• dE = dE(E,eta,Xi)

Better energy resolution better invmass resolution