ISMD 2004

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ISMD 2004
DIFFRACTION FROM THE DEEP SEA
Konstantin Goulianos The Rockefeller University
26 July 1 August 2004 Sonoma County,
California, USA
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Introduction
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Four Decades of Diffraction

• 1960s Good and Walker
• BNL first observation
• 1970s Fermilab fixed target, ISR, SPS
• Regge factorization works
• KG, Phys. Rep. 101, 169 (1983)
• 1980s UA8 diff. dijets a hard diffraction
• 1990s Tevatron Regge factorization
  breakdown
• TeV, HERA QCD factorization breakdown

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Soft Diffraction
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Total Elastic Cross Sections
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Renormalization

• Unitarity problem
• With factorization
• and std pomeron flux
• sSD exceeds sT at
• Renormalization
• normalize the Pomeron
• flux to unity

KG, PLB 358 (1995) 379
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A Scaling Law in Diffraction
KGJM, PRD 59 (1999) 114017
Factorization breaks down in favor of M2-scaling
renormalization
1
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Partonic Basis of Renormalization
(KG, hep-ph/0205141)
t
2 independent variables
Gap probability
Renormalization removes the s-dependence
SCALING
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The Factors k and e
Experimentally
KGJM, PRD 59 (114017) 1999
CTEQ5L
fggluon fraction fqquark fraction
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Central and Double Gaps

• Double Diffraction Dissociation
• One central gap

• Double Pomeron Exchange
  
• Two forward gaps

• SDD SingleDouble Diffraction
• One forward one central gap

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Generalized Renormalization
(KG, hep-ph/0205141)
Same suppression as for single gap!
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Central Double-Gap Results
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Soft Gap Survival Probability
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Soft Diffraction Conclusions
Experiment

• M2 scaling
• Non-suppressed double-gap to single-gap ratios

Phenomenology

• Generalized renormalization
• Obtain Pomeron intercept and tripe-Pomeron
• coupling from inclusive PDFs and color
  factors

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Soft vs Hard Diffraction

• SOFT DIFFRACTION

• HARD DIFFRACTION

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CDF-I
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Diffractive Fractions _at_ CDF
SD/ND fraction at 1800 GeV
DD/ND gap fraction at 1800 GeV

• All SD/ND fractions 1
• Gluon fraction
• Suppression by 5 relative to HERA
• ? gap survival probability 20

Factorization OK _at_ Tevatron at 1800 GeV (single
energy) ?
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Difftactive Structure Fn _at_CDF
SD/ND Rates vs

• Measure ratio of SD/ND dijet rates as a fn of
  
• In LO-QCD ratio of rates
• equals ratio of structure fns

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Breakdown of QCD Factorization
The clue to understanding the Pomeron
HERA
TEVATRON
p
x,t
IP
g
H1
e
CDF
gap
gap
dN/dh
dN/dh
h
h
???
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Restoring Diffractive Factorization
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Q2 dependence of DSF
Pomeron evolves similarly to proton except for
for renormalizartion effects
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Diffractive Structure Functionfrom the Deep Sea
eg0.20
Power-law region xmax 0.1 xmax 0.1 b eq0. 04
eR-0.5
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Pomeron Intercept from H1
1l
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x-dependence Inclusive vs Dijets
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Gap Between Jets
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Summary
SOFT DIFFRACTION

• M2 scaling
• Non-suppressed double-gap to single-gap ratios
• Flavor-independent SD/ND ratio
• Little or no Q2-dependence in SD/ND ratio

HARD DIFFRACTION

• Universality of gap probability in soft and hard
  diffraction
• Pomeron evolves similarly to proton

Diffraction appears to be a low-x partonic
exchange subject to color constraints