DIFFRACTION NEWS FROM CDF
Konstantin GoulianosThe Rockefeller University
http://physics.rockefeller.edu/dino/myhtml/conference.html
Otranto (Lecce), Italy
Hotel Baia dei Turchi September 10 - 15, 2010
DIFFRACTION 2010 International Workshop on Diffraction in High-Energy Physics
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 2 K. Goulianos
CONTENTS
Introduction
Diffractive W and Z production
Diffractive structure function in dijet production
Central gaps in min-bias and dijet events
Conclusions
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 3 K. Goulianos
DIFFRACTIVE AND NON-DIFFRACTIVE INTERACTIONS
Diffractive gaps Colorless exchange with vacuum quantum numbers
Non-diffractive no gaps Color-exchange
POMERON
Goal: understand the QCD nature of the diffractive exchange
rapidity gapIncident hadrons acquire colorand break apart
CONFINEMENT
Incident hadrons retain their quantum numbersremaining colorless
pseudo-DECONFINEMENT
p p p p
p
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 4 K. Goulianos
Definitions
s
Mξx1-
2
L
dN/dM
pp’
p’gap
=-ln0
p
M,t
p
p
p’ Lpξ
ln M2
ln s
particles=-ln
22 M
1
dM
dσξ1
dξdσ
constant0tΔηd
dσ
No radiation no price paid for increasingdiffractive gap size
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 5 K. Goulianos
Diffraction at CDF in Run I
Single Diffractiondissociation (SD)
Double Diffractiondissociation (DD)
Double PomeronExchange (DPE)
Single + DoubleDiffraction (SDD)
SD SD SD SDD
Elastic scattering Total cross sectionT=Im fel (t=0)
OPTICALTHEOREM
gap
“nested” gap
http://physics.rockefeller.edu/publications.html
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 6 K. Goulianos
TSD (pp & pp)
Factor of ~8 (~5)suppression at √s = 1800 (540) GeV
suppressed relative to Regge for √s>22 GeV
KG, PLB 358, 379 (1995)
1800
GeV
540
GeV
M,t
p
p
p’
TSD mb
√s=22 GeV
RENORMALIZATION MODEL
CDF Run I results
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 7 K. Goulianos
Diffractive Structure Function (DSF)
momentum fraction of parton in “Pomeron”
suppression factor is 2.5 times larger than in soft diffraction
Xdijetppp
breakdown of QCD factorization
PRL 84, 5043 (2000)
This contradicted the RENORM prediction that it should be ~ 8
as in soft diffraction~ 20
Run I
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 8 K. Goulianos
Hard diffractive fractions
dN/d
pbarp gaporgapX)(pp
1.45 +/- 0.25J/
0.62 +/- 0.25b
1.15 +/- 0.55W
0.75 +/- 0.10JJ
Fraction %Fraction:SD/ND ratio@ 1800 GeV
All fractions ~ 1% (differences due to
kinematics) ~ FACTORIZATION !
FACTORIZATION !
Run I
hard process
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 9 K. Goulianos
Puzzles from run I diffraction at CDF
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
DSF at √s=1800 GeV suppressed by factor ~ 20 while Regge by factor ~8 contradicts RENORM prediction
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 10 K. Goulianos
Why Run II Diffraction at CDF?
Resolve question on soft vs. hard diffraction suppression – are they really different? Make precise measurement of the DSF in dijets
– sensitive to gluon pdf’s Measure diffractive W/Z production
– sensitive to quark pdf’s Central gaps in soft and hard diffraction
– BFKL, Mueller-Navelet, other Aim to observe exclusive dijet production
– important for diffractive Higgs searches
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 11 K. Goulianos
The CDF II Detector – plan view
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 12 K. Goulianos
The MiniPlugs @ CDF
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 13 K. Goulianos
Measurements w/the MiniPlugs
ADC counts in MiniPlug towersin a pbar-p event at 1960 GeV.• “jet” indicates an energy cluster and may be just a hadron.• 1000 counts ~ 1 GeVMultiplicity of SD and ND events
ENERGY
MP TOWER
STRUCTURE
MULTIPLICITY
@ POSITION
NIM A 430 (1999)
NIM A 496 (2003)
NIM A 518 (2004)
s
eEΣξ
iηiTiCAL
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 14 K. Goulianos
Dynamic Alignment of RPS DetectorsMethod: 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-statistics2-beam size3-beam jitter
@ CDF W/lowlum data μm30
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 15 K. Goulianos
RPS acceptance
From PRD(submitted)
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 16 K. Goulianos
Diffractive W/Z productionstatus: submitted to PRD
In LO QCD W probes the quark content of diffractive exchange
Production by gluons is suppressed by a factor of S, and can be distinguished from quark production by an associated jet
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 17 K. Goulianos
Using RPS information:
No background from gaps due to multiplicity fluctuations No gap survival probability problem The RPS provides accurate event-by-event measurement Determine the full kinematics of diffractive W production by obtaining using the equation:
where
This allows determination of: W mass
and potentially (not enough range in present case)
xBj distribution
Diffractive structure function
νηTcalRPS es
Eξξ
Diffractive W/Z analysis
η
towers
Tcal es
Eξ
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 18 K. Goulianos
Data and event selection0.6 fb-1 of integrated luminosity data
W
Z
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 19 K. Goulianos
Reconstructed MWdiff
Reconstructed W mass using the 352 diffractive events fitted with a Gaussian.
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 20 K. Goulianos
MW from inclusive We/+vMethod: compare transverse MW data with MC
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 21 K. Goulianos
cal distribution
data
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 22 K. Goulianos
Diffractive W/Z fractions
~80% 68-80% ~87% f1-int =(25.6±1.2)%
RW (0.03 < < 0.10, |t|<1)= [0.97 ± 0.05(stat.) ± 0.10(syst.)]%
Run I: RW =1.15±0.55 % for min<<0.1
[0.97±0.47 (stat and syst) % within 0.03 < < 0.10 & |t|<1
RZ (0.03 < < 0.10, |t|<1)= [0.85 ± 0.20(stat.) ± 0.08(syst.)]%
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 23 K. Goulianos
DSF from Dijets in Run II
)(xF
)(xF
BjNDjj
BjSDjj
)(xRate
)(xRate)R(x
BjNDjj
BjSDjj
Bj
t - distribution
• The xBj-distribution of the SD/ND ratio has no strong Q2 dependence• the slope of the t-distribution is independent of Q2
• the t-distribution displays a diffraction minimum at |t| ~ 2.5 (GeV/c)2 (?) all three results “first observation”
?????? ??????
xBj - distribution
CDF Run II PreliminaryCDF Run II Preliminary
b - slope of t-distribution
?
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 24 K. Goulianos
Diffractive structure function – Run IIQ2 - dependence
ETjet ~ 100 GeV !
Small Q2 dependence in region 100<Q2<10 000 GeV2
where dSD/dET & dND/dET vary by a factor of ~104 !
The Pomeron evolves as the proton !
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 25 K. Goulianos
Diffractive structure function – Run IIt - dependence
No diffraction dips No Q2 dependence in slope from inclusive to Q2~104 GeV2
Fit d/dt to a double exponential:
Same slope over entire region of 0 < Q2 < ~ 10 000 GeV2!
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 26 K. Goulianos
Dijet ET distributions
similar for SD and ND over 4 orders of magnitude Kinematics
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 27 K. Goulianos
TSD and dijets
~8
ZEUS and H1 vs. CDF
ξ
xβ H1
ZEUS
CDFKG, PLB 358 (1995) 379
1dtdξξ)(t,f0.1
ξ
IP/p
0
tmin
Tsd
~ 8
soft*e
pp p
pp
dijet
Magnitude: same suppression factor in soft and hard diffraction!Shape of distribution: ZEUS, H1, and Tevatron – why different slapes?
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 28 K. Goulianos
CENTRAL GAPS
JetJet gap
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 29 K. Goulianos
SUMMARY 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. The W fraction is in good agreement with the fraction measured in Run I based on a rapidity gap analysis. The Z fraction is about 10% smaller than the W fraction, just as in non-diffractive events 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 youfor your
attendance
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 31 K. Goulianos
… use for last minute results
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 32 K. Goulianos
ξ
1
β
1~ξβ,FD
jj Pomeron dominated
constantdξ
dσincl
0.10.90.11.0
Djj ξ
1
β
1ξβ,F
& dependence of FDjj – Run I
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 33 K. Goulianos
D/ND dijet ratio vs. xBj@ CDF
(x)F
(x)FR(x) ND
jj
SDjj
0.035 < < 0.095
Flat dependencefor < 0.5
CDF Run I
DIFFRACTION 2010, 09/10-15 Otranto, ITALY Diffraction News from CDF 34 K. Goulianos
FDJJ(,Q2) @ Tevatron
2sβ
ξ
dξN
ε
ε
2sβ
1
β
xξ1
ξ 211
renorm
minmin
min
)2(
)(1
12
2R
2RENORM
xQs
xSDND
4.02.0 xg
)()(renorm
22
2
2
2 )(12
)/(
)(1N),,( 21221 Q
Q
Q
C
sx
CF D
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