DIFFRACTION NEWS FROM CDF DIFFRACTION 2010 International Workshop

DIFFRACTION NEWS FROM CDF DIFFRACTION 2010 International Workshop on Diffraction in High-Energy Physics Konstantin Goulianos The Rockefeller University http: //physics. rockefeller. edu/dino/myhtml/conference. html Otranto (Lecce), Italy Hotel Baia dei Turchi September 10 - 15, 2010 1

CONTENTS q Introduction q Diffractive W and Z production q Diffractive structure function in dijet production q Central gaps in min-bias and dijet events q Conclusions K. Goulianos 2

DIFFRACTIVE AND NON-DIFFRACTIVE INTERACTIONS Diffractive gaps v Colorless exchange with vacuum quantum numbers Non-diffractive no gaps v Color-exchange rapidity gap Incident hadrons acquire color and break apart Incident hadrons retain their quantum numbers remaining colorless p CONFINEMENT p p p P O M E R O N pseudo. DECONFINEMENT p Goal: understand the QCD nature of the diffractive exchange DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 3

Definitions p p p’ x, t M p p’ p M p’ d. N/dh gap Dh=-lnx particles 0 h ln M 2 ln s No radiation no price paid for increasing diffractive gap size DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 4

Diffraction at CDF in Run I http: //physics. rockefeller. edu/publications. html Elastic scattering f gap SD Single Diffraction dissociation (SD) h s. T=Im fel (t=0) OPTICAL THEOREM SD Double Diffraction dissociation (DD) Total cross section f h SD SDD Double Pomeron Exchange (DPE) Single + Double Diffraction (SDD) “nested” gap DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 5

s. TSD (pp & pp) p suppressed relative to Regge for √s>22 Ge. V mb √s=22 Ge. V 1800 Ge. V SD x, t M Factor of ~8 (~5) suppression at √s = 1800 (540) Ge. V 540 Ge. V s. T p p’ KG, PLB 358, 379 (1995) DIFFRACTION 2010, 09/10 -15 Otranto, ITALY CDF Run I results RENORMALIZATION MODEL Diffraction News from CDF K. Goulianos 6

Diffractive Structure Function (DSF) breakdown of QCD factorization Run I PRL 84, 5043 (2000) suppression factor is 2. 5 times larger than in soft diffraction ~ 20 This contradicted the RENORM prediction that it should be ~ 8 as in soft diffraction b momentum fraction of parton in “Pomeron” DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 7

Run I Hard diffractive fractions Fraction: SD/ND ratio @ 1800 Ge. V hard process d. N/dh h DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Fraction % JJ 0. 75 +/- 0. 10 W 1. 15 +/- 0. 55 b 0. 62 +/- 0. 25 J/y 1. 45 +/- 0. 25 All fractions ~ 1% (differences due to kinematics) Ø ~ FACTORIZATION ! ! Diffraction News from CDF K. Goulianos 8

Puzzles from run I diffraction at CDF q gap fractions are suppressed relative to theory predictions, both for soft (Regge) and hard diffraction …but factorization holds among processes at the same energy, just like at HERA q DSF at √s=1800 Ge. V suppressed by factor ~ 20 while Regge by factor ~8 contradicts RENORM prediction DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 9

Why Run II Diffraction at CDF? q Resolve question on soft vs. hard diffraction suppression – are they really different? q Make precise measurement of the DSF in dijets – sensitive to gluon pdf’s q Measure diffractive W/Z production – sensitive to quark pdf’s q Central gaps in soft and hard diffraction – BFKL, Mueller-Navelet, other q Aim to observe exclusive dijet production – important for diffractive Higgs searches DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 10

The CDF II Detector – plan view DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 11

The Mini. Plugs @ CDF DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 12

Measurements w/the Mini. Plugs MP TOWER STRUCTURE MULTIPLICITY @ POSITION ENERGY NIM A 430 (1999) NIM A 496 (2003) Multiplicity of SD and ND events DIFFRACTION 2010, 09/10 -15 Otranto, ITALY NIM A 518 (2004) ADC counts in Mini. Plug towers in a pbar-p event at 1960 Ge. V. • “jet” indicates an energy cluster and may be just a hadron. • 1000 counts ~ 1 Ge. V Diffraction News from CDF K. Goulianos 13

Dynamic Alignment of RPS Detectors Method: iteratively adjust the RPS X and Y offsets from the nominal beam axis until a maximum in the b-slope is obtained @ t=0. Limiting factors 1 -statistics 2 -beam size 3 -beam jitter @ CDF W/lowlum data DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 14

RPS acceptance From PRD (submitted) DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 15

Diffractive W/Z production status: submitted to PRD Ø In LO QCD W probes the quark content of diffractive exchange DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Ø Production by gluons is suppressed by a factor of a. S, and can be distinguished from quark production by an associated jet Diffraction News from CDF K. Goulianos 16

Diffractive W/Z analysis Using RPS information: q No background from gaps due to multiplicity fluctuations q No gap survival probability problem q The RPS provides accurate event-by-event x measurement q Determine the full kinematics of diffractive W production by obtaining hn using the equation: where This allows determination of: Ø W mass and potentially (not enough range in present case) § x. Bj distribution § Diffractive structure function DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 17

Data and event selection 0. 6 fb-1 of integrated luminosity data W Z DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 18

Reconstructed MWdiff q. Reconstructed W mass using the 352 diffractive events fitted with a Gaussian. DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 19

MW from inclusive W e/m+v Method: compare transverse MW data with MC DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 20

xcal distribution data DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 21

Diffractive W/Z fractions ~80% 68 -80% ~87% f 1 -int =(25. 6± 1. 2)% RW (0. 03 < x < 0. 10, |t|<1)= [0. 97 ± 0. 05(stat. ) ± 0. 10(syst. )]% Run I: RW =1. 15± 0. 55 % for xmin<x<0. 1 [0. 97± 0. 47 (stat and syst) % within 0. 03 < x < 0. 10 & |t|<1 RZ (0. 03 < x < 0. 10, |t|<1)= [0. 85 ± 0. 20(stat. ) ± 0. 08(syst. )]% DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 22

DSF from Dijets in Run II R(x Bj ) º Rate SD jj (x Bj ) Rate ND jj x. Bj - distribution (x Bj ) Þ Fjj. SD (x Bj ) Fjj. ND (x Bj ) b - slope of t-distribution CDF Run II Preliminary t - distribution CDF Run II Preliminary ? • The x. Bj-distribution of the SD/ND ratio has no strong Q 2 dependence • the slope of the t-distribution is independent of Q 2 ? ? ? a diffraction minimum at |t|? ? ? • the t-distribution displays ~ 2. 5 (Ge. V/c)2 (? ) Ø all three results “first DIFFRACTION 2010, 09/10 -15 Otranto, ITALY observation” Diffraction News from CDF K. Goulianos 23

Diffractive structure function – Run II Q 2 - dependence ETjet ~ 100 Ge. V ! Ø Small Q 2 dependence in region 100<Q 2<10 000 Ge. V 2 where ds. SD/d. ET & ds. ND/d. ET vary by a factor of ~104 ! The Pomeron evolves as the proton ! DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 24

Diffractive structure function – Run II t - dependence Fit ds/dt to a double exponential: Ø No diffraction dips Ø No Q 2 dependence in slope from inclusive to Q 2~104 Ge. V 2 DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Ø Same slope over entire region of 0 < Q 2 < ~ 10 000 Ge. V 2! Diffraction News from CDF K. Goulianos 25

Dijet ET distributions similar for SD and ND over 4 orders of magnitude DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF Kinematics K. Goulianos 26

p p s. TSD and dijets soft e p g* p dijet p ZEUS and H 1 vs. CDF s. Tsd ~8 ZEUS H 1 ~8 KG, PLB 358 (1995) 379 CDF b Magnitude: same suppression factor in soft and hard diffraction! Shape of b distribution: ZEUS, H 1, and Tevatron – why different slapes? DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 27

CENTRAL GAPS Jet DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF gap Jet K. Goulianos 28

SUMMARY q Results were presented for diffractive W and Z fractions based on Run II CDF data using a Roman Pot Spectrometer (RPS) to measure the recoil pbar momentum. q The W fraction is in good agreement with the fraction measured in Run I based on a rapidity gap analysis. q. The Z fraction is about 10% smaller than the W fraction, just as in non-diffractive events q A progress report was presented on the diffractive structure function in dijet production and on an analysis on central rapidity gaps in min-bias and very forward dijet events. thank you for your DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 29

BACKUP DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 30

… use for last minute results DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 31

x & b dependence of FDjj – Run I Pomeron dominated DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 32

D/ND dijet ratio vs. x. Bj@ CDF Run I 0. 035 < x < 0. 095 Flat x dependence for b < 0. 5 DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 33

FDJJ(x, b, Q 2) @ Tevatron DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 34

Diffractive dijets @ Tevatron jet p jet reorganize DIFFRACTION 2010, 09/10 -15 Otranto, ITALY Diffraction News from CDF K. Goulianos 35