Christina Mesropian The Rockefeller University

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1 Christina Mesroian The Rockefeller University

$Introduction Definition of diffractive rocesses Single Diffraction Hard Single Diffraction Soft Single diffraction Double Diffraction$

2 Introduction Definition of diffractive rocesses Single Diffraction Hard Single Diffraction Soft Single diffraction Double Diffraction Hard Double Diffraction Soft Double Diffraction Exclusive Central Production May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 2

$Diffractive reactions at hadron colliders are defined as reactions in which no quantum numbers are exchanged between colliding$

3 Diffractive reactions at hadron colliders are defined as reactions in which no quantum numbers are exchanged between colliding articles Diffractive: vacuum exchange Non-diffractive: color exchange May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 3

4 Goals of Diffractive Program at CDF: To understand the nature of colorless exchange To test the feasibility of diffraction as a tool to search for new hysics at the LHC Non- Diffractive (ND) Single Diffraction (SD) Double Diffraction (DD) _ Identified by resence of: intact leading article large raidity ga _ or Higgs, dijets, }, c Double Pomeron Exchange (DPE) May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 4

5 Tevatron Collider May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 5 _ 3 center-of-mass energies Run I ( ) s=1.8 TeV (~120 b -1 ) Tevatron Run IC ( ) s=630 GeV Run II (2001- current ) s= 1.96 TeV

1 0 < t < 2 GeV 2 BSC Beam Shower Counters 5.4 < < 7.

6 Tracking Tracking Detectors < 2.0 CCAL, PCAL Calorimeters < 3.6 RPS Roman Pot Sectrometers 0.02 < < < t < 2 GeV 2 BSC Beam Shower Counters 5.4 < < 7.4 MPCAL MiniPlug Calorimeters 3.5 < < 5.1 May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 6

7 Fiber Tracker 3 stations 57 meters from IP 3 trigger counters 240 channels MIPs ( >1000 counts) May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 7

8 BSCs are located along beam ie used for triggering events with forward raidity gas BSC-2,3,4 BSC-1 May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 8

electromagnetic and hadronic showers towerless geometry no dead

9 Nucl. Instrum. Meth. A518 (2004) 42. Nucl. Instrum. Meth. A496 (2003) 333. designed to measure the energy and lateral osition of both electromagnetic and hadronic showers towerless geometry no dead regions May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 9

$Diffractive signature: recoil bar or large raidity ga Soft Diffraction Single Diffraction PRD 50, 5355 (1994) Hard Diffraction Raidity Ga$ $8 TeV PRL 84, 5043 (2000) 630 GeV PRL 88, 151802 (2002) t - four-momentum transfer squared - fractional momentum loss of bar β fraction of$

10 Diffractive signature: recoil bar or large raidity ga Soft Diffraction Single Diffraction PRD 50, 5355 (1994) Hard Diffraction Raidity Ga Tag W PRL 78, 2698 (1997) Dijets PRL 79, 2636 (1997) b-quark PRL 84, 232 (2000) J/ PRL 87, (2001) Roman Pot Tag Dijets: 1.8 TeV PRL 84, 5043 (2000) 630 GeV PRL 88, (2002) t - four-momentum transfer squared - fractional momentum loss of bar β fraction of P momentum carried by arton M X - mass of system X =M X2 /s x= May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 10 ra-ga =-ln 0 ξ _ M X dn/d

$multile interactions soiling diffractive signatures use cal < 0.$

11 Results are mostly MC free Determine using Roman Pots tracking Also can determine from E T in calorimeters imortant to have MiniPlugs cal towers E T s e Main challenge: multile interactions soiling diffractive signatures use cal < 0.1 to reject overla events non-diffractive contributions May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 11

12 Diffractive dijet cross section D ( X ) Fjj Fjj ˆ( ab jj) Study the diffractive structure function D F D F ( x, Q 2, t, ) jj jj Exerimentally determine diffractive structure function D F jj ZEUS _ H1 at LO R SD ND D 2 ( SDjj ) Fjj ( x, Q, ( x, ) 2 ( ND ) F ( x, Q ) Data jj jj known PDF ) CDF Factorization breakdown ga survival May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 12

$1 e b2 t no diffractive dis no Q 2 deendence in sloe from inclusive to Q 2 ~ 10 4 GeV 2 May 15, 2010 Christina Mesroian$

13 Good agreement with Run I results Fit to double exonential function: d /dt 0.9 e b1 t e b2 t no diffractive dis no Q 2 deendence in sloe from inclusive to Q 2 ~ 10 4 GeV 2 May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 13

14 _ Diffractive signature: large raidity ga slightly different ga definitions Fraction: R SD/ND 1800 GeV Hard comonent Fraction ( R ) % Dijet W b J/ 1.45 v 0.25 All fractions ~ 1% (differences due to kinematics) ~ uniform suression May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 14

$Diffractive W/Z roduction robes the quark content of the Pomeron to Leading Order the W/Z are roduced by a quark in the Pomeron roduction by gluons is$

15 Diffractive W/Z roduction robes the quark content of the Pomeron to Leading Order the W/Z are roduced by a quark in the Pomeron roduction by gluons is suressed by a factor of S and can be distinguished by an associated jet IP IP W, Z W, Z May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 15

16 Raidity gas method CDF Phys Rev Lett 78, 2698 (1997) Fraction of W events due to SD [1.15±0.51(stat) ± 0.20(syst) ]% DØ Phys Lett B 574, 169 (2003) Fraction of events with raidity ga (uncorrected for ga survival) W: [ ]% Z: [ ]% May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 16

17 Identify diffractive events using Roman Pots: accurate event-by-event ξ measurement no ga accetance correction needed can still calculate ξ cal E cal T towers s e In W roduction, the difference between ξ cal and ξ RP is related to missing E T and η ν RP cal allows to determine: neutrino and W kinematics E T s e reconstructed diffractive W mass May 15, 2010 x bj Christina Mesroian "RHIC Sin: The Next Decade" 17

$of diffractive W R W (0.03< <0.10, t <1)= [0.97 ±0.05(stat) ±0.$

18 cal < RP requirement removes most events with multile bar- interactions 50 < M W < 120 GeV/c 2 requirement on the reconstructe W mass cleans u ossible mis-reconstructed events Fraction of diffractive W R W (0.03< <0.10, t <1)= [0.97 ±0.05(stat) ±0.10(syst)]% consistent with Run I result, extraolated to all May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 18

$37 diffractive Z ee/ candidates (RP track, cal <0.$

19 37 diffractive Z ee/ candidates (RP track, cal <0.1) estimate 11 overla ND+SD background events based on ND cal distribution Fraction of diffractive Z R Z (0.03< <0.10, t <1)= [0.85±0.20(stat) ±0.08(syst)]% May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 19

$Diffractive signature: large central raidity ga slightly different ga definitions Soft Diffraction Double Diffraction PRL 87, 141802 (2001) Hard Diffraction Jet-Ga_Jet 1.$

20 Diffractive signature: large central raidity ga slightly different ga definitions Soft Diffraction Double Diffraction PRL 87, (2001) Hard Diffraction Jet-Ga_Jet 1.8 TeV PRL 74, 855 (1995) 1.8 TeV PRL 80, 1156 (1998) 630 GeV PRL 81, 5278 (1998) tracks only _ floating ga fixed ga May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 20

21 R=[ (stat) 1800 GeV R=[ (stat) 630 GeV floating jets fixed central ga fixed central ga R is estimated using OS jets as signal and SS jets as a control samle look for events with raidity ga in <1 when jets are at 1.8< <3.5 both track and tower multilicities roduce similar results May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 21

$Soft Double-Diffraction (DD) _ PRL floating 87, (2001) ga 141803$ max η min η max (η min )- article closest to η=0 in the ()

22 Soft Double-Diffraction (DD) _ PRL floating 87, (2001) ga Strategy of analysis: look for exerimental gas defined as Δη η max η min η max (η min )- article closest to η=0 in the () direction May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 22

23 _ jet _ M 1 jet To comare ga robability in soft and hard DD dissociation: reconstruct in both cases require events to have ga in CCAL <1.1 => => significant DD contribution require oosite side MP jets for hard DD, with E T >2 GeV Direct comarison of the results is relatively free of systematic uncertainties. May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 23 M 2 For this analysis we use floating not-necessarily central ga

MP CCAL and PCAL MP bar Run 211073 events 85601 Gas: what is under the caret?

24 MP CCAL and PCAL MP bar Run events Gas: what is under the caret? - detector noise etc May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 24

PRL 87, (2001) 141803 fixed jets floating ga soft DD comare with jet jet hard DD Fraction of events with gas: ~10% in soft DD events and

25 PRL 87, (2001) fixed jets floating ga soft DD comare with jet jet hard DD Fraction of events with gas: ~10% in soft DD events and ~1% in jet events The distributions are similar in shae within the uncertainties May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 25

$Diffractive signature: recoil bar /large raidity ga AND large raidity ga on roton side _ Soft Diffraction Double Pomeron Exc.$

26 Diffractive signature: recoil bar /large raidity ga AND large raidity ga on roton side _ Soft Diffraction Double Pomeron Exc. PRL 93, (2004) Multi-Ga Diffraction PRL 91, (2003) Hard Diffraction Dijets: 1.8 TeV PRL 85, 4217 (2000) 1.96 TeV PRD 77, (2008) Di-hotons 1.96 TeV PRL 99, (2007) Charmonium 1.96 TeV PRL 102, (2009) Inclusive DPE distribution second ga roduction is not suressed May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 26

27 LHC CDF _ (no underlying event) At the Tevatron we use similar rocesses with larger cross sections to test and calibrate theor. redictions Dijets,, } suression at LO of the background sub-rocesses (J z =0 selection rule) exclusive channel clean signal c May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 27

$RUN I RUN II Method: Select inclusive diffractive dijet events _ roduced _ by DPE + IP + IP +X( 2 jets)+ga CDF limit of σ excl <3.$

28 RUN I RUN II Method: Select inclusive diffractive dijet events _ roduced _ by DPE + IP + IP +X( 2 jets)+ga CDF limit of σ excl <3.7 nb(95% CL) M Reconstruct jj - dijet mass,m X R jj M M jj X - massof, where systemx May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 28

$fraction Signal at R jj =1 is$ smeared due to

29 PRD 77, (2008) Observe excess over inclusive DPE dijet MC s at high dijet mass fraction Signal at R jj =1 is smeared due to shower/hadronization _ effects, NLO gg ggg,qqg contributions May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 29

30 data Signal MC ExHuME CPC 175,232 (2006) Exclusive DPE as inut to DPEMC CPC 167,217 (2005) bkgd signal fit Shae of excess described by exclusive dijet MC based on two models (ExHuME, DPEMC), shows good agreement May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 30

Calculation by Khoze, Martin, and Ryskin consistent within its factor of 3

31 Exclusive dijet cross section comared with MC based on two models : ExHuME, and excl. DPE DPEMC. Cross section disfavors exclusive DPE model. Calculation by Khoze, Martin, and Ryskin consistent within its factor of 3 uncertainty. Eur. Phys J C14, 525 (2000). May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 31

Phys.Rev.Lett. 99,242002 (2007) E T ( ) > 5 GeV ( ) < 1.0 Method for excl.

32 Phys.Rev.Lett. 99, (2007) E T ( ) > 5 GeV ( ) < 1.0 Method for excl. search is calibrated vs excl e+e- analysis: 3 candidates observed: 2 events are good candidates 1 event is good 0 0 candidate Theoretical Prediction: V.A.Khoze et al. Eur. Phys. J C38, 475 (2005) (with our cuts) = ( ) fb = events. Cannot yet claim discovery as b/g study a osteriori, 2 events corresond to ~ 90 fb, agreeing with Khoze et al. May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 32

33 GeV/c 2 <M <4 GeV/c 2 Many Physics Processes in this data: exclusive c in DPE Observation of exclusive c PRL (2009) May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 33

J/ roduction 243 21 events d /dy y=0 = 3.92 ± 0.62 nb Theoretical Predictions 2.8 nb [Szczurek07,], 2.7 nb [Klein&Nystrand04], 3.0 nb [Conclaves&Machado05], and 3.4 nb [Motkya&Watt08].

34 J/ roduction events d /dy y=0 = 3.92 ± 0.62 nb Theoretical Predictions 2.8 nb [Szczurek07,], 2.7 nb [Klein&Nystrand04], 3.0 nb [Conclaves&Machado05], and 3.4 nb [Motkya&Watt08]. s roduction PRL (2009) Fit : 2 Gaussians + QED continuum May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 34 J/ QED continuum 34 7 events d /dy y=0 = 0.54 ± 0.15 nb R = (2s)/J/ = 0.14 ± 0.05 In agreement with HERA: R = ± in a similar kinematic region (2s)

35 PRL (2009) J/ = +66 events Allow extra EM tower (2s) = +1 event Allowing EM towers (E T >80MeV) large increase in the J/ eak minor change in the (2s) eak Evidence for c J / + roduction d /dy y=0 = 75 ± 14 nb, comatible with theoretical redictions 160 nb (Yuan 01) 90 nb (KMR01) May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 35

36 Very diverse diffractive rogram at CDF: measurements at 3 different c.o.m. energies introduced new methods for diffractive studies at hadron-hadron colliders designed and constructed new detectors for forward regions Majority of measurements are MC free Different identifications of diffractive event signatures: Results between RPS and large raidity ga are consistent. May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 36

37 May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 37

1 QCD factorization breakdown Regge factorization

38 ~10 1/ξ behavior discreancy in normalization D n m for 0.5 F C jj n QCD factorization breakdown Regge factorization holds m omeron exchange May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 38

39 E E / e T T 40 Z ( vtx μ T ) 25 GeV M W T 25 GeV 60 cm 120 GeV 60 cm May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 39 E E 66 e1 T e2 T Z ( ( vtx μ1 T μ2 T M Diffractive W/Z selection ) ) Z 25 GeV 25 GeV 116 GeV RPS trigger counters require MIP RPS track < <0.10, t <1GeV 2 W cal < RP, 50 < M W ( RPS, cal ) < 120 GeV 2 Z cal < 0.1

40 R W (0.03 < < 0.10, t <1)= [0.97 ± 0.05(stat) ± 0.11(syst)]% Run I: R W ( <0.1 )=[1.15±0.55] % 0.97±0.47 % in 0.03 < < 0.10 & t <1 R Z (0.03 < x < 0.10, t <1)= [0.85 ± 0.20(stat) ± 0.11(syst)]% CDF/DØ Comarison Run I ( < 0.1) CDF PRL 78, 2698 (1997) R w =[1.15±0.51(stat)±0.20(syst)]% ga accetance A ga =0.81 Uncorrected for A ga R w =(0.93±0.44)% DØ Phys Lett B 574, 169 (2003) R w =[5.1±0.51(stat)±0.20(syst)]% ga accetance A ga =(0.21±4)% Uncorrected for A ga R W =[ ]% R Z =[ ]% May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 40

41 MP jet is defined as a vector ointing to a cluster with seed tower (E T > 400 MeV) and 1 layer of surrounding towers MP Jet energy = energy of the seed tower + energy of the towers in the layer surrounding the seed jet cone radius R = 0.4 (0.7) May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 41

LO exclusive gg qq suressed (J Z =0 rule) Look for heavy flavor jet suression relative to inclusive dijets at high Rjj Suression of heavy flavor for R jj > 0.

42 LO exclusive gg qq suressed (J Z =0 rule) Look for heavy flavor jet suression relative to inclusive dijets at high Rjj Suression of heavy flavor for R jj > 0.4 is consistent in shae and magnitude with the results based on MC based extraction of exclusive dijet signal. May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 42

43 derived from CDF excl. dijet x- sections using ExHuME Stat. and syst. errors are roagated from measured cross section uncertainties using M jj distribution shaes of ExHuME generated data. May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 43

44 W e Kinematics similar for SD and ND electrons are boosted away from anti-rotons in diffractive samle May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 44

45 Nucl. Instrum. Meth. A518 (2004) 42. Nucl. Instrum. Meth. A496 (2003) 333. to detect forward jets 3.6< <5.2 we use MiniPlug Calorimeters for ga studies need low luminosity run average luminosity L ~ 1x10 30 cm -2 s -1 May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 45

46 _ _ + Trigger: 3 GeV/c 2 <M <4 GeV/c 2 muon + track + forward raidity gas in BSCs 2 oositely charged muon tracks with T >1.4 GeV/c, <0.6 excl ~0.093 => L=1.48 fb -1 but L eff ~140b -1 May 15, 2010 Christina Mesroian "RHIC Sin: The Next Decade" 46

Hard Diffraction Results and Prospects at the Tevatron

$Hard Diffraction Results and Prospects at the Tevatron$ Hard Diffraction Results and Prosects at the Tevatron University of Manchester On behalf of the CDF & DØ Collaboration ISMD 2005 14 th August, Kromeriz Tevatron Tevatron at Fermilab -collisions Run II: