GSIM studies of DVCS

1
GSIM studies of DVCS
H. Avakian
e1DVCS meeting 9/30/05

1. GSIM update
2. Comparison with e1-DVCS data
3. Low momentum protons

2
GSIM update
New field map from SACLAY group
GSIM code updated using IC/SOL code by Hyon-Suk
and F.-X
Example of the new ffread file
Example of how to run the new DVCS gsim available
from
3
Simulation Generated events
DVCS/p0 generator used for the event sample,

• The updated GSIM allow input in the LUND format.
• p0-generator includes also etta and ee-g decays

example
Data e1-DVCS preliminary data
4
Data/MC comparison neutrals
MC
data
5
Data/MC comparison protons
DC off for few runs
6
Data/MC comparison electrons
7
Data/MC comparison
Cut on qgXlt0.15
Difference between measured and calculated angles
for photons and pi0s
8
MC studies proton momentum
with multiple scattering
no multiple scattering
qPgt59o
9
MC studies p0 contamination
p0
10
MC studies proton momentum correction
no multiple scattering
Measured momentum
11
MC studies
with multiple scattering
12
MC studies electron energy correction
with multiple scattering
13
MC studies missing mass distributions
no target field
with target field
14
MC studies missing mass distributions
no multiple scattering
no target field
with target field
15
MC studies proton angular shift
no target field
with target field
16
MC studies proton angular shift
e1-DVCS data
17
Summary

1. GSIM simulation consistent with data
2. GSIM used for momentum corrections
3. Contamination of pi0 extracted
4. Shift observed in angular distributions of protons

Use GSIM for angular correction and data analysis