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Diffraction @ CDF

Diffraction @ CDF. Konstantin Goulianos The Rockefeller University. The Future of QCD at the Tevatron Fermilab, 20-22 May 2004. CDF Run I results. Run I. Run 1-0 (1988-89). Elastic, single diffractive, and total cross sections @ 546 and 1800 GeV. Roman Pot Spectrometers.

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Diffraction @ CDF

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  1. Diffraction @ CDF Konstantin Goulianos The Rockefeller University The Future of QCD at the TevatronFermilab, 20-22 May 2004

  2. CDF Run I results The Future of QCD: Diffraction @CDFK. Goulianos

  3. Run I The Future of QCD: Diffraction @CDFK. Goulianos

  4. Run 1-0 (1988-89) Elastic, single 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 Additional Detectors Trackers up to |h| = 7 • Results • Total cross section stot ~ se • Elastic cross section ds/dt ~ exp[2a’ lns]  shrinking forward peak • Single diffraction Breakdown of Regge factorization The Future of QCD: Diffraction @CDFK. Goulianos

  5. f y f y Total & Elastic Cross Sections (Run I-0) The exponential rise of sT is a QCD aspect expected in the parton model (see E. Levin, An Introduction to Pomerons,Preprint DESY 98-120) The Future of QCD: Diffraction @CDFK. Goulianos

  6. Soft Diffraction (Run I-0) • Unitarity problem: With factorization and std pomeron flux sSD exceeds sT at • Renormalization: normalize the pomeron flux to unity ~10 KG, PLB 358 (1995) 379 The Future of QCD: Diffraction @CDFK. Goulianos

  7. M2-scaling KG&JM, PRD 59 (1999) 114017 Factorization breaks down in favor of M2-scaling renormalization 1 The Future of QCD: Diffraction @CDFK. Goulianos

  8. color factor QCD Basis for Renormalization (KG, hep-ph/0205141) t 2 independent variables: Gap probability Renormalization removes the s-dependence M2-SCALING The Future of QCD: Diffraction @CDFK. Goulianos

  9. Color factor: Pomeron intercept: lg=0.20 lq=0.04 fg=gluon fraction fq=quark fraction lR=-0.5 k and e Experimentally: KG&JM, PRD 59 (114017) 1999 The Future of QCD: Diffraction @CDFK. Goulianos

  10. Run-IC Run-IA,B Forward Detectors BBC 3.2<h<5.9 FCAL 2.4<h<4.2 CDF-I The Future of QCD: Diffraction @CDFK. Goulianos

  11. Soft Central and Double Gaps • Double Diffraction Dissociation • One central gap • Double Pomeron Exchange • Two forward gaps • SDD: Single+Double Diffraction • One forward + one central gap The Future of QCD: Diffraction @CDFK. Goulianos

  12. 5 independent variables color factors Gap probability Sub-energy cross section (for regions with particles) Generalized Renormalization (KG, hep-ph/0205141) Same suppression as for single gap! The Future of QCD: Diffraction @CDFK. Goulianos

  13. Differential shapes agree with Regge predictions DD SDD DPE • One-gap cross sections are suppressed • Two-gap/one-gap ratios are Central & Double-Gap Results The Future of QCD: Diffraction @CDFK. Goulianos

  14. S = Soft Gap Survival Probability The Future of QCD: Diffraction @CDFK. Goulianos

  15. 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 PDF’s and color factors Soft diffraction is understood ! (?) The Future of QCD: Diffraction @CDFK. Goulianos

  16. Hard Diffraction • Diffractive Fractions • Diffractive Structure Function • Factorization breakdown and restoration • DSF from inclusive PDF’s • Hard diffraction conclusions The Future of QCD: Diffraction @CDFK. Goulianos

  17. X Fraction(%) W 1.15 (0.55) JJ 0.75 (0.10) b 0.62 (0.25) J/y 1.45 (0.25) Diffractive Fractions 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 @ Tevatron at 1800 GeV (single energy) The Future of QCD: Diffraction @CDFK. Goulianos

  18. Diffractive Structure F‘n • Measure ratio of SD/ND dijet rates as a f’n of • In LO-QCD ratio of rates equals ratio of structure fn’s SD/ND Rates vs The Future of QCD: Diffraction @CDFK. Goulianos

  19. IP IP p p p p 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 ??? The Future of QCD: Diffraction @CDFK. Goulianos

  20. R(SD/ND) R(DPE/SD) DSF from double-gaps: Factorization restored! DSF from single-gaps Restoring Diffractive Factorization The Future of QCD: Diffraction @CDFK. Goulianos

  21. lg=0.5 lq=0.3 DSF from Inclusive pdf’s (KG) eg=0.20 Power-law region xmax = 0.1 xmax = 0.1 b < 0.05x eq=0. 04 eR=-0.5 The Future of QCD: Diffraction @CDFK. Goulianos

  22. RENORM Pomeron Intercept from H1 1+l The Future of QCD: Diffraction @CDFK. Goulianos

  23. lg=0.5 lq=0.3 Pomeron+Reggeon Pomeron dominated x-dependence: Inclusive vs Dijets The Future of QCD: Diffraction @CDFK. Goulianos

  24. Enery Dependence of FJJD Phenomenological Models: • Renormalization Phys. Lett. B 358, 379 (1995). • Gap survival probability, e.g. Eur.Phys. J. C 21, 521 (2001). • Soft color interactions Phys. Rev. D 64, 114015 (2001). R630/1800(predicted) ~ 1.5 - 1.8 R630/1800 = 1.3±0.2(stat)+0.4/-0.3(syst) The Future of QCD: Diffraction @CDFK. Goulianos

  25. Hard Diffraction Conclusions Diffraction appears to be a low-x exchange subject to color constraints The Future of QCD: Diffraction @CDFK. Goulianos

  26. Summary of Run I Results SOFT DIFFRACTION • M2– scaling • Non-suppressed double-gap to single-gap ratios • Flavor-independent SD/ND ratios • Factorization breakdown and restoration HARD DIFFRACTION • Universality of gap prob. across soft and hard diffraction The Future of QCD: Diffraction @CDFK. Goulianos

  27. Run II Diffractive Program • Single Diffraction • x and Q2 dependence of FjjD • Process dependence of FD (W, b,J/y,...) • Double Diffraction • Jet-Gap-Jet: Dhgap for large fixed Dhjet • Double Pomeron Exchange • FjjD on p-side vs x-pbar Also: Exclusive central production • Dijets, cc, low mass states, Higgs(!)(?)… Other • Open to suggestions The Future of QCD: Diffraction @CDFK. Goulianos

  28. Tag leading p-bar @ 0.02 < x< 0.1 Reject (retain) 95% of ND (SD)events detect forward particles CDF-II The Future of QCD: Diffraction @CDFK. Goulianos

  29. MiniPlug Calorimeter About 1500 wavelength shifting fibers of 1 mm dia. are ‘strung’ through holes drilled in 36x¼” lead plates sandwiched between reflective Al sheets and guided into bunches to be viewed individually by multi-channel photomultipliers. The Future of QCD: Diffraction @CDFK. Goulianos

  30. 84 towers 5.5 in 25 in Artist’s View of MiniPlug The Future of QCD: Diffraction @CDFK. Goulianos

  31. ~ no Q2 dependence ~ flat at HERA ~ 1/x0.5 at Tevatron Q2 dependence of DSF Pomeron evolves similarly to proton except for for renormalizartion effects The Future of QCD: Diffraction @CDFK. Goulianos

  32. Question Hard Double Diffraction Run I Results The Future of QCD: Diffraction @CDFK. Goulianos

  33. Interest indiffractive Higgs production Calibrate on exclusive dijets Dijet mass fraction no peak! Upper limit for excl DPE-jj consistent with theory Exclusive Dijets in DPE The Future of QCD: Diffraction @CDFK. Goulianos

  34. 10 cc candidates Search for Exclusive cc @CDF • Events are triggered on dimuons • Select muons with PT>1.5 GeV, |h|< 0.6 • Reject cosmic rays using time of flight information • Select events in J/y mass window No positive identification of cc events Cross section upper limit comparable to KMR prediction The Future of QCD: Diffraction @CDFK. Goulianos

  35. Merits/Problems/Needs Merits of CDF Run II diffractive program • Measuring xwith calorimeters  full acceptance  overlap rejection • BSC gap triggers  can take data at high luminosities But: • BSC gap rejects some diffractive events from MP spillover • Useful rates too low for many processes, e. g. exclusive b-bbar Need: • Low luminosity runs for calibrations: • x-roman pot vs x-calorimeter • BSC gap trigger vs roman pot trigger Also need: • $$$ to instrument MPs from current 84 to all 256 channels for EM/hadron discrimination and better jet definition The Future of QCD: Diffraction @CDFK. Goulianos

  36. CONCLUSION Run II • CDF has a comprehensive Run II diffractive program • Modest upgrades & special runs are desirable • Full MiniPlug instrumentation • Low luminosity (~1030) runs for calibrations • Data run at 630 GeV Beyond Run II • Can think of improvements, but of no compelling diffractive physics that cannot be done in Run II The Future of QCD: Diffraction @CDFK. Goulianos

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