Download presentation
Presentation is loading. Please wait.
1
Diffraction @ CDF The Future of QCD at the Tevatron Fermilab, 20-22 May 2004 Konstantin Goulianos The Rockefeller University
2
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos2 CDF Run I results
3
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos3 Run I Run #Datespb -1 Physics 1-01988-89~5 Elastic, Diffractive & Total x-sections 1-A,B1992-95~120 Rapidity Gaps 1-C1995-96~10Roman Pots
4
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos4 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 Results Total cross section tot ~ s Elastic cross section d /dt ~ exp[2 ’ ln s ] shrinking forward peak Single diffraction Breakdown of Regge factorization Additional Detectors Trackers up to | | = 7
5
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos5 Total & Elastic Cross Sections The exponential rise of T is a QCD aspect expected in the parton model (see E. Levin, An Introduction to Pomerons,Preprint DESY 98-120) y y (Run I-0)
6
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos6 Unitarity problem: With factorization and std pomeron flux SD exceeds T at Renormalization: normalize the pomeron flux to unity Soft Diffraction (Run I-0) KG, PLB 358 (1995) 379 ~10
7
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos7 M 2 -scaling KG&JM, PRD 59 (1999) 114017 Factorization breaks down in favor of M 2 -scaling renormalization 1
8
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos8 2 independent variables: Gap probability Renormalization removes the s-dependence M 2 -SCALING QCD Basis for Renormalization t color factor (KG, hep-ph/0205141)
9
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos9 and Experimentally: KG&JM, PRD 59 (114017) 1999 g =0.20 q =0.04 R =-0.5 f g =gluon fraction f q =quark fraction Color factor: Pomeron intercept:
10
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos10 CDF-I Run-ICRun-IA,B Forward Detectors BBC 3.2< <5.9 FCAL 2.4< <4.2
11
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos11 Double Diffraction Dissociation One central gap Double Pomeron Exchange Two forward gaps SDD: Single+Double Diffraction One forward + one central gap Soft Central and Double Gaps
12
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos12 Gap probabilitySub-energy cross section (for regions with particles) Generalized Renormalization Same suppression as for single gap! 5 independent variables color factors (KG, hep-ph/0205141)
13
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos13 One-gap cross sections are suppressed Two-gap/one-gap ratios are Central & Double-Gap Results Differential shapes agree with Regge predictions DDSDDDPE
14
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos14 Soft Gap Survival Probability S =
15
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos15 Soft Diffraction Conclusions M 2 – scaling Non-suppressed double-gap to single-gap ratios Experiment: Phenomenology: Generalized renormalization Obtain Pomeron intercept and tripe-Pomeron coupling from inclusive PDF’s and color factors Soft diffraction is understood ! (?)
16
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos16 Hard Diffraction Diffractive Fractions Diffractive Structure Function Factorization breakdown and restoration DSF from inclusive PDF’s Hard diffraction conclusions
17
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos17 Factorization OK @ Tevatron at 1800 GeV (single energy) All SD/ND fractions ~1% Gluon fraction Suppression by ~5 relative to HERA gap survival probability ~20% Diffractive Fractions 1.45 (0.25)J/ 0.62 (0.25)b 0.75 (0.10)JJ 1.15 (0.55)W Fraction(%) X SD/ND fraction at 1800 GeVDD/ND gap fraction at 1800 GeV
18
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos18 Diffractive Structure F‘n SD/ND Rates vs Measure ratio of SD/ND dijet rates as a f’n of In LO-QCD ratio of rates equals ratio of structure fn’s
19
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos19 Breakdown of QCD Factorization dN/d gap e ** HERA TEVATRON dN/d gap pp IP t CDF H1 pp IP p ??? The clue to understanding the Pomeron
20
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos20 Restoring Diffractive Factorization R(SD/ND)R(DPE/SD) DSF from double-gaps: Factorization restored! DSF from single-gaps
21
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos21 DSF from Inclusive pdf’s (KG) Power-law region max = 0.1 x max = 0.1 < 0.05 g =0.20 q =0. 04 R =-0.5 g =0.5 q =0.3
22
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos22 Pomeron Intercept from H1 RENORM 1+
23
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos23 -dependence: Inclusive vs Dijets g =0.5 q =0.3 Pomeron dominated Pomeron+Reggeon
24
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos24 Enery Dependence of F JJ D R 630/1800 = 1.3±0.2(stat)+0.4/-0.3(syst) 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). R 630/1800 (predicted) ~ 1.5 - 1.8
25
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos25 Hard Diffraction Conclusions Diffraction appears to be a low-x exchange subject to color constraints
26
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos26 Summary of Run I Results M 2 – scaling Non-suppressed double-gap to single-gap ratios Flavor-independent SD/ND ratios Factorization breakdown and restoration SOFT DIFFRACTION Universality of gap prob. across soft and hard diffraction HARD DIFFRACTION
27
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos27 Run II Diffractive Program Single Diffraction and Q 2 dependence of F jj D Process dependence of F D (W, b,J/ Double Diffraction Jet-Gap-Jet: gap for large fixed jet Double Pomeron Exchange F jj D on p-side vs -pbar Also: Exclusive central production Dijets, c, low mass states, Higgs(!)(?)… Other Open to suggestions
28
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos28 CDF-II Tag leading p-bar @ 0.02 < < 0.1 Reject (retain) 95% of ND (SD)events detect forward particles
29
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos29 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.
30
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos30 Artist’s View of MiniPlug 25 in 5.5 in 84 towers
31
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos31 Q 2 dependence of DSF ~ no Q 2 dependence ~ flat at HERA ~ 1/ x 0.5 at Tevatron Pomeron evolves similarly to proton except for for renormalizartion effects
32
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos32 Hard Double Diffraction Question Run I Results
33
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos33 Exclusive Dijets in DPE Interest in diffractive Higgs production Calibrate on exclusive dijets Upper limit for excl DPE-jj consistent with theory Dijet mass fraction no peak!
34
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos34 Search for Exclusive c @CDF Events are triggered on dimuons Select muons with P T >1.5 GeV, | |< 0.6 Reject cosmic rays using time of flight information Select events in J/ mass window 10 c candidates No positive identification of c events Cross section upper limit comparable to KMR prediction
35
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos35 Merits/Problems/Needs Merits of CDF Run II diffractive program Measuring with 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: -roman pot vs -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
36
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos36 CONCLUSION Run II CDF has a comprehensive Run II diffractive program Modest upgrades & special runs are desirable Full MiniPlug instrumentation Low luminosity (~10 30 ) 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
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.