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AZIMUTHAL DISTRIBUTIONOF
DIJETSIN
DIFFRACTIVE DIS
David Šálek
December 8, 2005
Diffractive Meeting, Antwerpen
BOSON GLUON FUSION & TWO GLUON EXCHANGE MODEL
AZIMUTHAL ANGLE
definition of the azimuthal angle in gamma-p CMS
CUTS
Kinematical cuts: 8 < Q2 < 100
-35 < zvertex < 35
0.05 < yBjorken < 0.7
35 < E - pz < 70
Scattered electron cuts: Espacal > 8
Rspacal > 9.1
Jet cuts: pT > 3.5
-3 < etagamma-p < 0
Diffractive cuts: etamax < 3.2
PRT 0, 1, 2, 3, 4 < 1
FMD 0+1, 2 < 2
xPomeron < 0.04
DATA
99-00 data
sub-trigger 61
prescale < 15
1223 events
MONTE CARLO
RAPGAP inclusive diffraction for F2D(3) at medium Q2
generator: RAPGAP 2.08/18
files from Tinne Anthonis for 99-00
pomeron uds N = 5000000
L = 205.39 pb-1
pomeron c N = 500000
L = 179.16 pb-1
meson N = 4489194
L = 95.36 pb-1
Boson Gluon Fusion4344 events QCD Compton
MONTE CARLO
QUARK & GENERATED JET CORELATION
LEADING JET
QUARK & GENERATED JET CORELATION
SECOND JET
GENERATED & RECONSTRUCTED JET CORELATION
LEADING JET
GENERATED & RECONSTRUCTED JET CORELATION
SECOND JET
AZIMUTHAL ANGLE
Problemat
generator level:
no W-shape
Problemat
reconstructed level:
Lorentz transformation
PROBLEM AT GENERATOR LEVEL
azimuthal distribution is not smooth
LORENTZ TRANSFORMATION
gamma-p CMS:
4-vector of incoming proton4-vector of exchanged gamma q = k – k’
k’ not correctly reconstructed
it results in deviation of azimuthal distribution at reconstructed level
GENERATED & RECONSTRUCTED ELECTRON
CORELATION BETWEEN GENERATOR & RECONSTRUCTED LEVEL
SCATTERED ELECTRONENERGY
xPomeron & etamax
CORELATION BETWEEN GENERATOR & RECONSTRUCTED LEVEL
COMPARISON OF DATA & MONTE CARLO
dead spacal region
problem with final state radiation:
electron properties
basic kinematic variables
Lorentz transformation
temporary solution:take only those events wherethere is only the scattered electron in spacal
etaLab > -1
zvertex & BASIC KINEMATICAL VARIABLES
SCATTERED ELECTRON
xgamma & E - pz
DIFFRACTIVE VARIABLES
FORWARD MUON DETECTORSPROTON REMNANT TAGGER
way to improve agreement between data and MC:
FMD noise
good agreement needed only to calculate luminosity correctly
adding FMD noise decreases MC statistics
JET CHARACTERISTICS
LEADING JET
SECOND JET
HFS CALIBRATION ???
SUMMARY & OUTLOOK
retrieve W-shaped azimuthal distribution for BGF at parton level
reconstruct electron properties better in order to reveal generated azimuthal distribution at reconstructed level
increase statistics by including events with final state radiation with proper corrections to radiated gammas
generate Monte Carlo files with two gluon exchange
unfolding