Transcript Document

Measuring bremsstrahlung photons in pp
collisions (update)
Ali Hanks
Group Meeting
Oct. 16, 2006
Hard/Photon Analysis Fest
10/20/06
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Method
• Fragmentation photons are correlated with high pT jets
– Use h- correlations to select photons associated with jets
• Tagging method for estimating decay photon background
– Tag photons from 0 using invariant mass distribution
– Estimate tagging efficiency with fastmc
Hard/Photon Analysis Fest
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Method (cont’d)
• Associated 0-decay per trigger yield:
• Include contribution from other hadronic decays:
• Associated frag per trigger yield:
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h-inc per trigger yield
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h-tagged per trigger yield
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Tagging efficiency
• Simulation generates 0s in a
guassian distribution around a
“trigger” hadron

0
– distribution is pT dependant
trigger
– determined from real data
hadron- ∆f distribution
• Let these 0s decay and compare
resulting h- Df distribution for
single photon acceptance and pair
acceptance
two particle
acceptance
three particle
acceptance
∆f
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0 distribution from data
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0 distribution from data
•
Use sigma values from fit as input for distributions generated in same pT bins
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Tagging efficiency estimates
• Study tagging efficiency as a function of Df in same pT bins as data
• Still need to do this with input 0 spectrum from pp
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h-tagged per trigger yield
• With estimated tagging efficiency included
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h-subtracted per trigger yield
• h-inc – h-tagged with tagging efficiency included
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To Do
• Complete work on subtraction of h-decay
– Study tagging to check for possible over-tagging
– Check esitmate of tagging efficiency for errors
– contribution from other hadronic decays
• Still not clear if shape is same as for 0
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Hot tower Maps
•
hot towers for cluster with
pT from 1-2 GeV/c
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Hot tower Maps
• hot towers for cluster
with pT from 2-3
GeV/c
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Hot tower Maps
• hot towers for cluster
with pT from 3-20
GeV/c
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Tagging efficiency
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