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Diffraction for all: from Tevatron to LHC and Beyond

Diffraction for all: from Tevatron to LHC and Beyond. Konstantin Goulianos The Rockefeller University. HEP 2006, December 11-15, Valparaiso, Chile. Recent references Diffraction at the Tevatron: CDF results http://pos.sissa.it//archive/conferences/035/016/DIFF2006_016.pdf

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Diffraction for all: from Tevatron to LHC and Beyond

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  1. Diffraction for all:from Tevatron to LHC and Beyond Konstantin Goulianos The Rockefeller University HEP 2006, December 11-15, Valparaiso, Chile Recent references Diffraction at the Tevatron: CDF results http://pos.sissa.it//archive/conferences/035/016/DIFF2006_016.pdf Renormalized diffractive parton densities http://pos.sissa.it//archive/conferences/035/044/DIFF2006_044.pdf

  2. Contents • Introduction • Elastic and Total Cross Sections • Diffraction • Exclusive Production Diffraction for allK. Goulianos

  3. Incident hadrons acquire color and break apart POMERON CONFINEMENT p-p Interactions Non-diffractive: Color-exchange Diffractive: Colorless exchange with vacuum quantum numbers rapidity gap Incident hadrons retain their quantum numbers remaining colorless pseudo- DECONFINEMENT Goal: understand the QCD nature of the diffractive exchange Diffraction for allK. Goulianos

  4. Elastic Scattering Diffraction for allK. Goulianos

  5. COHERENCE CONDITION Diffraction Dissociation Momentum loss fraction x< 0.1 Tevatron M  0.6 TeV LHC  4.4 TeV Diffraction for allK. Goulianos

  6. xp p p p X X ln s f Particle production Rapidity gap ln MX2 -ln x h Rapidity Gaps Diffraction for allK. Goulianos

  7. Diffractive pp Processes sT=Im fel (t=0) Elastic scattering Total cross section f f OPTICAL THEOREM GAP h h DD DPE SDD=SD+DD SD Diffraction for allK. Goulianos

  8. Rapidity Gaps in Fireworks Diffraction for allK. Goulianos

  9. The Physics • Elastic and Total Cross Sections:……….pppp and ppX • Fundamental Quantum Mechanics • Froissart Unitarity Bound……….sT < C ln2s • Optical theorem………………………..sT ~Im f(t=0) • Dispersion relations………………....Re f(t=0)~Im f(t=0) • Is space-time discrete?  Measure sT and r-value at LHC! • Diffraction Dissociation:………………pppX, XgX, pXp, pXgX, … • Non-perturbative QCD • Soft & hard diffraction • Factorization • Multi-gap diffraction • Diffraction in QCD:…….……what is the Pomeron? • Dark energy? • Exclusive Production:………………….…..pppp+H (jet+jet, g+g, …, H0) • Discovery channel • Diffractive Higgs production at the LHC (?) Diffraction for allK. Goulianos

  10. Tevatron Experiments Diffraction for allK. Goulianos

  11. CDF Run 1-0 (1988-89) Elastic, diffractive, and total cross section @ 546 and 1800 GeV Roman Pot Spectrometers CDF-I • Roman Pot Detectors • Scintillation trigger counters • Wire chamber • Double-sided silicon strip detector Roman Pots with Trackers up to |h| = 7 Diffraction for allK. Goulianos

  12. Run-IC CDF-I Run-IA,B beam Forward Detectors BBC 3.2<h<5.9 FCAL 2.4<h<4.2 Diffraction for allK. Goulianos

  13. ROMAN POT DETECTORS BEAM SHOWER COUNTERS: Used to reject ND events MINIPLUG CALORIMETER CDF-II Diffraction for allK. Goulianos

  14. The MiniPlugs @ CDF Diffraction for allK. Goulianos

  15. p S S CDF & D0 - Run II p CDF RP2 BSC4 BSC3 BSC2 BSC2 BSC3 D Q4 Q3 Q2 Q2 Q3 Q4 Z(m) RP3 RP1 MP 3.5<η<5.5 BSC1 5.5<η<7.5 0 57 23 32 23 32 CDF & D0: COMPLIMENTARY COVERAGE D0 P1U P2O Q4 Q3 Q2 Q2 S D Q3 Q4 S A1 D1 A2 D2 P1D P2I Z(m) LM 2.5<η<4.4 VC 5.2<η<5.9 57 0 59 23 33 23 33 From Barreto’s talk in small-x Diffraction for allK. Goulianos

  16. ELASTIC AND TOTAL CROSS SECTIONS @ Tevatron: CDF and E710/811  use luminosity independent method  Optical theorem optical theorem • Alert: • background Ninel yields small sT • undetected Ninel yields large sT Diffraction for allK. Goulianos

  17. sT and r-values from PDG r = ratio of real/imaginary parts of elastic scattering amplitude at t=0 CDF CDF and E710/811 disagree E710 E811 sT optical theorem Im fel(t=0) dispersion relations Re fel(t=0) CDF & UA4 E811 N. Khuri and A. Martin: measuring r at the LHC tests discreteness of space-time Diffraction for allK. Goulianos

  18. Total Cross Sections: Regge fit CDF E710 CMG: Covolan, Montagna, and G PLB 389 (1995) 176 Born level Simultaneous Regge fit to pp, pp, and Kp x-sections using the eikonal approach to ensure unitarity s  Se e = 1.104 +/- 0.002  sLHC= 115 mb @14 TeV DL Diffraction for allK. Goulianos

  19. Recall CMG Regge fit: 115 mb Other Approaches eg, M. Block, arXiv:hep-ph/0601210(2006)  fit data using analyticity constraints M. Block and F. Halzen, Phys. Rev. D 72, 036006 • sT (LHC) = 107.3 ± 1.2 mb Diffraction for allK. Goulianos

  20. TOTEM experiment @ LHC Total Cross Section, Elastic Scattering, and Diffraction Dissociation Aim at 1% accuracy on sT RP stations CMS RP stations CMS/TOTEM LOI: Prospects for Diffractive and Forward Physics at the LHC Diffraction for allK. Goulianos

  21. SOFT DIFFRACTION Key words: renormalization scaling QCD multi-gap • Dark energy ??? Diffraction for allK. Goulianos

  22. Renormalization Factorization  Pomeron flux • Regge theory sSD exceeds sT at • Renormalization Pomeron flux integral (re)normalized to unity KG, PLB 358 (1995) 379 Diffraction for allK. Goulianos

  23. renormalization 1 A Scaling Law in Diffraction KG&JM, PRD 59 (1999) 114017  Independent of S over 6 orders of magnitude in M2 ! Factorization breaks down so as to ensure M2-scaling! Diffraction for allK. Goulianos

  24. f y The QCD Connection f Total cross section: power law increase versus s y ~1/as The exponential rise of sT(Dy’) is due to the increase of wee partons with Dy’ (E. Levin, An Introduction to Pomerons,Preprint DESY 98-120) Elastic cross section: forward scattering amplitude Diffraction for allK. Goulianos

  25. Single Diffraction in QCD (KG, hep-ph/0205141) t 2 independent variables: color factor Gap probability Renormalization removes the s-dependence SCALING Diffraction for allK. Goulianos

  26. 5 independent variables color factors Gap probability Sub-energy cross section (for regions with particles) Same suppression as for single gap! Multi-gap Renormalization (KG, hep-ph/0205141) Diffraction for allK. Goulianos

  27. Central and Double Gaps @ CDF • Double Diffraction Dissociation • One central gap • Double Pomeron Exchange • Two forward gaps • SDD: Single+Double Diffraction • One forward + one central gap Diffraction for allK. Goulianos

  28. Differential shapes agree with Regge predictions DD SDD DPE • One-gap cross sections are suppressed • Two-gap/one-gap ratios are Central & Double-Gap CDF Results Diffraction for allK. Goulianos

  29. Non-diffractive interactions Diffractive interactions Rapidity gaps are formed by multiplicity fluctuations: Rapidity gaps at t=0 grow with Dy: 2e: negative particle density! P(Dy) is exponentially suppressed Gravitational repulsion? Dark Energy Diffraction for allK. Goulianos

  30. dN/dh h HARD DIFFRACTION • Diffractive fractions • Diffractive structure function  factorization breakdown • Restoring factorization • Q2 dependence • t dependence • Hard diffraction in QCD JJ, W, b, J/y Diffraction for allK. Goulianos

  31. Diffractive Fractions @ CDF Fraction(%) Fraction: SD/ND ratio at 1800 GeV All ratios ~ 1% ~ uniform suppression ~ FACTORIZATION ! W 1.15 (0.55) JJ 0.75 (0.10) b 0.62 (0.25) J/y 1.45 (0.25) Diffraction for allK. Goulianos

  32. Diffractive Structure Function:Breakdown of QCD Factorization b = momentum fraction of parton in Pomeron The diffractive structure function at the Tevatron is suppressed by a factor of ~10 relative to expectation from pdf’s measured by H1 at HERA Similar suppression factor as in soft diffraction relative to Regge expectations! H1 CDF Using preliminary pdf’s from Diffraction for allK. Goulianos

  33. R(SD/ND) R(DPE/SD) DSF from two/one gap: factorization restored! Restoring QCD Factorization The diffractive structure function measured on the proton side in events with a leading antiproton is NOT suppressed relative to predictions based on DDIS Diffraction for allK. Goulianos

  34. Diffractive Structure Function:Q2 dependence ETjet ~ 100 GeV ! • Small Q2 dependence in region 100 < Q2 < 10,000 GeV2 • Pomeron evolves as the proton! Diffraction for allK. Goulianos

  35. Diffractive Structure Function:t- dependence Fit ds/dt to a double exponential: • No diffraction dips • No Q2 dependence in slope from inclusive to Q2~104 GeV2 • Same slope over entire region of 0 < Q2 < 4,500 GeV2 across soft and hard diffraction! Diffraction for allK. Goulianos

  36. p p valence quarks antiproton antiproton Hard Diffraction in QCD deep sea valence quarks Derive diffractive from inclusive PDFs and color factors x=x proton Diffraction for allK. Goulianos

  37. H EXCLUSIVE PRODUCTION Measure exclusive jj & gg  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………………………… KMR: sH(LHC) ~ 3 fb S/B ~ 1 if DM ~ 1 GeV Clean discovery channel • Search for exclusive gg • 3 candidate events found • 1 (+2/-1) predicted from ExHuME MC* • background under study * See talk by V. Khoze Search for exclusive dijets: Measure dijet mass fraction Look for signal as Mjj 1 Diffraction for allK. Goulianos

  38. Exclusive Dijet Signal Dijet fraction – all jets b-tagged dijet fraction DIJETS Exclusive b-jets are suppressed by JZ= 0 selection rule Excess over MC predictions at large dijet mass fraction Diffraction for allK. Goulianos

  39. RJJ(excl): Data vs MC Exclusive DPE (DPEMC)  non-pQCD based on Regge theory ExHuME (KMR): gggg process  uses LO pQCD Shape of excess of events at high Rjj is well described by both models Diffraction for allK. Goulianos

  40. jjexcl: Exclusive Dijet Signal COMPARISON Inclusive data vs MC @ b/c-jet data vs inclusive Diffraction for allK. Goulianos

  41. JJexcl : x-section vs ET(min) Comparison with hadron level predictions ExHuME (red) Exclusive DPE in DPEMC (blue) Diffraction for allK. Goulianos

  42. JJexcl : 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 Mjj distribution shapes. Diffraction for allK. Goulianos

  43. Looking forward@ LHC TOTEM/CMS ATLAS • FP420 project: http://www.fp420.com/ • Measure protons at 420 m from the IP during normal high luminosity running to be used in conjunction with CMS and ATLAS • Feasibility study and R&D for Roman Pot detector development • Physics aim :pp  p+ X + p (Higgs, New physics, QCD studies) • Status: Project funded by the UK Diffraction for allK. Goulianos

  44. Summary TEVATRON – what we have learnt • M2 – scaling • Non-suppressed double-gap to single-gap ratios • Pomeron: composite object made up from underlying pdf’s subject to color constraints LHC - what to do • Elastic and total cross sections & r-value • High mass (4 TeV)and multi-gap diffraction • Exclusive production (FP420 project)  Reduced bgnd for std Higgs to study properties  Discovery channel for certain Higgs scenarios Diffraction for allK. Goulianos

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