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The Future of QCD: Diffraction at CDFK

The study at CDFK focused on diffraction in QCD, exploring factors like color fractions, pomeron properties, and structure functions. Results suggest a need for generalized renormalization to address unitarity and factorization breakdowns. Findings indicate M2-scaling may replace traditional factorization. The experiment also examines single, double, and central gaps, offering insights into hard and soft diffraction phenomena. The research provides valuable conclusions on diffractive fractions, restoration of factorization, and the energy dependence of diffractive processes.

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The Future of QCD: Diffraction at CDFK

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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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