New results on diffractive t-distributions from CDF Konstantin Goulianos The Rockefeller University (for the CDF Collaboration) DIS-2012 DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos1

CONTENTS  MOTIVATION  diffraction in QCD  diffraction in CDF: factorization breaking  how does factorization breaking affect t distributions?  t DISTRIBUTIONS : inclusive and dijet data  forward detectors with /roman pot spectrometer (RPS)  dynamic alignment of RPS  t-distributions vs. Q 2 ≈ (E T,jet ) 2 over a wide range: ~ 1 ≤ Q 2 ≤ 10 4 GeV 2 and t min (~0) ≤ -t ≤ 4 GeV 2  search for a diffraction minimum  SUMMARY DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos2

DIFFRACTION IN QCD Diffractive  Colorless vacuum exchange  large-gap signature Non-diffractive  color-exchange  gaps exponentially suppressed POMERONPOMERON Goal : probe the QCD nature of the diffractive exchange rapidity gap Incident hadrons acquire color and break upart CONFINEMENT Incident hadrons retain their quantum numbers remaining colorless pseudo- DECONFINEMENT p ppp p DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos3

DIFFRACTION IN CDF Single Diffraction or Single Dissociation Double Diffraction or Double Dissociation Double Pom. Exchange or Central Dissociation Single + Double Diffraction (SDD) SD DD DPE /CD SDD Elastic scatteringTotal cross section  T =Im f el (t=0) OPTICAL THEOREM   gap   DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos4

Factor of ~8 (~5) suppression at √s = 1800 (540) GeV  diffractive x-section suppressed relative to Regge prediction as √s increases see KG, PLB 358, 379 (1995) 1800 GeV 540 GeV M ,t,t p p p’ √s=22 GeV RENORMALIZATION Regge EXAMPLE OF FACTORIZATION BREAKING IN DIFFRACTION CDFCDF  Question: does factorization breaking affect t distributions? DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos5

SINGLE DIFFRACTION pp MXMX dN/d  ,t,t p MXMX p p’ Rap-gap  =-ln  0 ln s ln M 2 ln s No radiation  no price paid for increasing diffractive gap size DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos6

The CDF II Detector |  |<2  |  | <3.6  3.5<|  |< <|  |<7.4 ~0.02<  <0.1 0 < t <4 GeV 2 PLAN VIEW DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos7

The RPS IN CDF II DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos8

The MiniPlugs  overlap bgnd (BG) is reduced by including the MPs in the  CAL calculation DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos9 CDF Run II Preliminary

 CAL vs.  RPS slice DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos10 CDF Run II Preliminary

TRIGGERS AND EVENT SAMPLES DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos11

Dynamic Alignment of RPS Method: iteratively adjust the RPS X and Y offsets from the nominal beam axis until a maximum in the b-slope is t=0. Limiting factors 1-statistics 2-beam size 3-beam jitter use RPStrk data width~ 2 mm/√N N~1 K events  X,  Y = ± 60  New: uncertainty in the slope due to alignment ±2 mm DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos12

slowly varying at high t 0.05 <  <0.08  acceptance beyond 4 GeV 2 minimizes edge effects RPS ACCEPTANCE DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos13 CDF Run II Preliminary

DATA REDUCTION DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos14 CDF Run II Preliminary

t-distributions for -t≤1 GeV 2  No diffraction dips  No Q 2 dependence in slope from inclusive to Q 2 ~10 4 GeV 2 Fit d  /dt to a double exponential: DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos15 CDF Run II Preliminary

b-slopes for -t≤1 GeV 2 (1 )  ≤ 20% dependence on Q 2 over ~ 4 orders of magnitude DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos16 CDF Run II Preliminary

b-slopes for -t≤1 GeV 2 (2) DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos17 CDF Run II Preliminary

Dijet E T *-distributions:  similar for SD and ND over 3 orders of magnitude! DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos18 CDF Run II Preliminary

t >1 GeV 2 : asymmetric t-distributions as a tool for evaluating bgd at high t 2 mm 2.5 mm p p 7.5 mm 12.5 mm x Y 25 mm  tracker’s upper edge: |t|=2.3 GeV 2, estimated from t~  2  the lower edge is at |t|= 6.5 GeV 2 (not shown)  background level: region of Y track >Y o data for |t|>2.3 GeV 2 bgnd = 20 evts/GeV 2 schematic view of fiber tracker t-distributions Y = 7.5 mm DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos19 CDF Run II Preliminary

Why select 0.05<  pbar <0.08?  be on the plateau of the ds/dln  distribution  allow enough room to avoid edge-effects  accept enough events for good statistics  estimated width resulting from the  :  ≈ 0.47 DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos20 CDF Run II Preliminary

t-distributions for -t≤4 GeV 2 DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos21 CDF Run II Preliminary

CONCLUSION DIS-2012, Bonn, GERMANY Diffractive t-distributions from CDF K. Goulianos  t DISTRIBUTIONS : inclusive and dijet data  measured over a wide range of Q 2 ≈ (E T,jet ) 2 : ~ 1 ≤ Q 2 ≤ 10 4 GeV 2 and t min (~0) ≤ -t ≤ 4 GeV 2  independent of Q 2  agree with the DL model at -t ≤ ~0.5 GeV 2  flatten out beyond -t ~1.5 to become a factor of ~10 larger than the DL model prediction 22 THANK YOU FOR YOUR ATTENTION