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Diffraction at CDF 12th International Conference on Elastic and Diffractive Scattering Forward Physics and QCD – Blois2007 Hamburg, Germany, 21-25 May 2007 K. Goulianos The Rockefeller University (for the CDF collaboration)
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos2 Contents Introduction Diffractive structure function Exclusive Production
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos3 p-p Interactions Diffractive: Colorless exchange with vacuum quantum numbers Non-diffractive: Color-exchange Incident hadrons retain their quantum numbers remaining colorless Incident hadrons acquire color and break apart POMERONPOMERON Goal: understand the QCD nature of the diffractive exchange rapidity gap
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos4 Definitions pp MXMX dN/d ,t,t p MXMX p p’ rapgap =-ln
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos5 Diffraction at CDF Elastic scatteringTotal cross section SD DDDPESDD=SD+DD T =Im f el (t=0) OPTICAL THEOREM GAP
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos6 Rapidity Gaps in Fireworks
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos7 CDF Run-I0 (1988-89) Elastic, diffractive, and total cross sections @ 546 and 1800 GeV Roman Pot Spectrometers Roman Pot Detectors Scintillation trigger counters Wire chamber Double-sided silicon strip detector Roman Pots with Trackers up to | | = 7 CDF-I
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos8 Regge theory SD exceeds T at Renormalization Pomeron flux integral (re)normalized to unity Total SD x-section KG, PLB 358 (1995) 379 Pomeron flux Factorization
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos9 A Scaling Law in Diffraction KG&JM, PRD 59 (1999) 114017 Factorization breaks down so as to ensure M 2 -scaling! renormalization 1 Independent of S over 6 orders of magnitude in M 2 !
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos10 CDF Run-I Run-ICRun-IA,B Forward Detectors BBC 3.2< <5.9 FCAL 2.4< <4.2 beam
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos11 Double Diffraction Dissociation One central gap Double Pomeron Exchange Two forward gaps SDD: Single+Double Diffraction One forward gap+ one central gap Central and Multigap Diffraction Rate for second diffractive gap is not suppressed!
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos12 All ratios ~ 1% ~ uniform suppression ~ FACTORIZATION ! Diffractive Fractions 1.45 (0.25)J/ 0.62 (0.25)b 0.75 (0.10)JJ 1.15 (0.55)W Fraction(%) Fraction: SD/ND ratio at 1800 GeV
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos13 Diffractive non /Factorization R(SD/ND) R(DPE/SD) DSF from two/one gap: factorization restored! The diffractive structure function measured on the proton side in events with a leading antiproton is NOT suppressed relative to predictions based on DDIS =momentum fraction of parton in Pomeron =x Bj /
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos14 Run II results CDF-II detectors Diffractive structure function Exclusive Production
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos15 CD-II Detectors ROMAN POT DETECTORS BEAM SHOWER COUNTERS: Used to reject ND events MINIPLUG CALORIMETER
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos16 The MiniPlugs @ CDF
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos17 DIFFRACTIVE STRUCTURE FUNCTION Systematic uncertainties due to energy scale and resolution cancel out in the ratio
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos18 Diffractive Dijet Signal Overlap events: mainly ND dijets plus SD low RPS trigger - Bulk of data taken with RPS trigger but no RPS tracking - Extract from calorimeter information - Calibrate calorimetric using limited sample of RPS tracking data - Subtract overlap background using a rescaled dijet event sample - Verify diffractive range by comparing RPS with CAL
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos19 Alignment of RPS using Data maximize the |t|-slope determine X and Y offsets
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos20 CAL Calibration overlap events signal region cal distribution for slice of RPS / mean ~ 30%
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos21 Dijet Properties SD boosted opposite to pbar p p jet
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos22 E T distributions 120 GeV
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos23 Diffractive Structure Function: Q 2 dependence E T jet ~ 100 GeV ! Small Q 2 dependence in region 100 < Q 2 < 10,000 GeV 2 Pomeron evolves as the proton!
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos24 Diffractive Structure Function: t- dependence No diffraction dips No Q2 dependence in slope from inclusive to Q 2 ~10 4 GeV 2 Fit d /dt to a double exponential: Same slope over entire region of 0 < Q 2 < 4,500 GeV 2 across soft and hard diffraction!
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos25 valence quarks antiproton x=x= Hard Diffraction in QCD proton deep sea Derive diffractive from inclusive PDFs and color factors antiproton valence quarks p p
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos26 EXCLUSIVE PRODUCTION H Measure exclusive jj & Calibrate predictions for H production rates @ LHC Bialas, Landshoff, Phys.Lett. B 256,540 (1991) Khoze, Martin, Ryskin, Eur. Phys. J. C23, 311 (2002); C25,391 (2002);C26,229 (2002) C. Royon, hep-ph/0308283 B. Cox, A. Pilkington, PRD 72, 094024 (2005) OTHER………………………… Search for exclusive dijets: Measure dijet mass fraction Look for signal as R jj 1 Search for exclusive 3 candidate events found 1 (+2/-1) predicted from ExHuME MC estimated ~1 bgd event from 0 0, KMR: H (LHC) ~ 3 fb S/B ~ 1 if M ~ 1 GeV Discovery channel
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos27 Exclusive e + e - Production PRL 98, 112001 (2007) First observation in hadron colliders
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos28 Exclusive Dijet Signal b-tagged dijet fraction Dijet fraction – all jets Exclusive b-jets are suppressed by J Z = 0 selection rule Excess over MC predictions at large dijet mass fraction DIJETSDIJETS
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos29 R JJ (excl): Data vs MC Shape of excess of events at high R jj is well described by both models ExHuME (KMR): gg gg process uses LO pQCD Exclusive DPE (DPEMC) non-pQCD based on Regge theory
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos30 jj excl : Exclusive Dijet Signal COMPARISON Inclusive data vs MC @ b/c-jet data vs inclusive
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos31 JJ excl : x-section vs E T (min) Comparison with hadron level predictions ExHuME (red) Exclusive DPE in DPEMC (blue)
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos32 JJ excl : cross section predictions ExHuME Hadron-Level Differential Exclusive Dijet Cross Section vs Dijet Mass (dotted/red): Default ExHuME prediction (points): Derived from CDF Run II Preliminary excl. dijet cross sections Statistical and systematic errors are propagated from measured cross section uncertainties using ExHuME M jj distribution shapes.
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Blois Workshop 2007 DESY, Hamburg, Germany May 21-25 Diffraction at CDF K. Goulianos33 Summary CDF - what we have learnt M 2 – scaling d /M 2 not a function of s multigap diffraction restoration of factorization! flavor independence of diffractive fractions small Q2 dependence of SD/ND x BJ -distributions t-distributions independent of Q2 exclusive dijet cross sections favor the perturbative QCD over the DPE approach LHC - what to do Elastic and total cross sections & -value High mass ( 4 TeV) and multi-gap diffraction Exclusive production (FP420 project) For a QCD perspective, see Tuesday’s talk on: “Pomerom Intercept and Slope: the QCD connection”
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