erjet Energy Flow . Patrick Ryan, Univ. of Wisconsin QCD Meeting , April 7, 2005 - 1 Patrick Ryan University of Wisconsin Claire Gwenlan Oxford University April 18, 2005 Interjet Energy Flow Interjet Energy Flow Monday Meeting http://www-zeus.desy.de/~pryan/ rap_gap
Interjet Energy Flow. Patrick Ryan University of Wisconsin Claire Gwenlan Oxford University April 18, 2005. Monday Meeting http://www-zeus.desy.de/~pryan/rap_gap. Hard Diffractive g p. Use pQCD to study diffraction Hard Diffractive Photoproduction Hard: High E T Jets (E T > 5 GeV) - PowerPoint PPT Presentation
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Interjet Energy Flow . Patrick Ryan, Univ. of Wisconsin QCD Meeting , April 7, 2005 - 1
Patrick Ryan University of Wisconsin
Claire GwenlanOxford University
April 18, 2005
Interjet Energy FlowInterjet Energy FlowInterjet Energy FlowInterjet Energy Flow
Monday Meeting
http://www-zeus.desy.de/~pryan/rap_gap
Rapidity Gaps. Patrick Ryan. Univ. of Wisconsin Collaboration Meeting , Oct.. 15, 2003 - 2
Hard Diffractive Hard Diffractive ppHard Diffractive Hard Diffractive pp
• Use pQCD to study diffraction• Hard Diffractive Photoproduction
• Hard: High ET Jets (ET > 5 GeV)• Diffractive: Gap between jets • Photoproduction: Q2 ~ 0
t
q
Standard DiffractionHard Diffractive p
Rapidity Gap
Rapidity Gaps. Patrick Ryan. Univ. of Wisconsin Collaboration Meeting , Oct.. 15, 2003 - 3
Topology of Rapidity GapsTopology of Rapidity GapsTopology of Rapidity GapsTopology of Rapidity Gaps
Distance between jet centers: •ET
Gap = Total ET between leading and trailing jets
•Gap Event: ETGap < ET
Cut
•Gap indicates color singlet exchange
Jet
Jet
Gap
Remnant
p Remnant0
2
-2.4 2.4
Trailing
LeadingLeading Jet
Trailing Jet
Remnant
-3
3
0
2
Rapidity Gaps. Patrick Ryan. Univ. of Wisconsin Collaboration Meeting , Oct.. 15, 2003 - 4
The Gap FractionThe Gap FractionThe Gap FractionThe Gap Fraction
Expectation for Behavior of Gap Fraction (J.D. Bjorken, V.Del Durca, W.-K. Tung)*
2 3 4
fGap
fGapSinglet fGap
n-s
dd
ddf Gap
/
/)(
Singletgap
SingletNongapGap
All Dijet Events with large Rapidity separationDijet Events with large Rapidity separation and ET
Gap < ETCut
•Non-Singlet• f() decreases exponentially with • Particle production fluctuations Gap• Non diffractive exchange
•Singlet• f() constant in
*Phys. Rev. D47 (1992) 101
Phys Lett. B312 (1993) 225
Rapidity Gaps. Patrick Ryan. Univ. of Wisconsin Collaboration Meeting , Oct.. 15, 2003 - 5
Simulation of Simulation of p Eventsp EventsZEUS - AMADEUSZEUS - AMADEUS
Simulation of Simulation of p Eventsp EventsZEUS - AMADEUSZEUS - AMADEUS
• PYTHIA 6.1 and HERWIG 6.1 MC
• Direct and Resolved MC generated separately• Resolved MC includes Multi Parton Interactions
• Dir and Res combined by fitting xdistributions to data (next slide)
• PDFs• PDF(p): GRV-LO
• PDF(): WHIT 2
• Color Singlet Exchange MC• PYTHIA: High-t
• Purpose is simply to match the data
• Note: Rapidity Gap not due to photon exchange
• HERWIG: BFKL
• Uses BFKL Pomeron as exchange object in Rapidity Gap events
Interjet Energy Flow . Patrick Ryan, Univ. of Wisconsin QCD Meeting , April 7, 2005 - 6
Event Selection and xEvent Selection and x Fitting FittingZEUS - AMADEUSZEUS - AMADEUS
Event Selection and xEvent Selection and x Fitting FittingZEUS - AMADEUSZEUS - AMADEUS
•ZEUS 96-97 Data• Luminosity: 38 pb-1
•Offline Cleaning Cuts• |zvtx| < 40 cm• No Sinistra95 e+ with
• Pe > 0.9, Ee > 5 GeV, ye < 0.85• 0.2 < yjb < 0.85