New Results on Diffractive and Exclusive Production
from CDF Konstantin Goulianos
The Rockefeller University
(for the CDF Collaboration)
DIS-2013, Marseille Diffractive and Exclusive Production at CDF K. Goulianos 1
http://dis2013.in2p3.fr/
http://physics.rockefeller.edu/dino/my.html
CONTENTS Introduction
Diffraction in QCDDiffraction at CDF
DefinitionsFactorization breaking in soft diffractionExclusive production of: dijet-2008, dimuonc-J/(2s)-2009, -2012
Central Exclusive Production of +- NEW!
DIS-2013, Marseille Diffractive and Exclusive Production at CDF K. Goulianos 2
DIFFRACTION IN QCD
Diffractive events
Colorless vacuum exchange
-gaps not suppressed
Non-diffractive events
color-exchange -gaps exponentially suppressed
POMERON
Goal: probe the QCD nature of the diffractive exchange
rapidity gap
p p p p
p
DIS-2013, Marseille Diffractive and Exclusive Production at CDF K. Goulianos 3
DIFFRACTION AT CDF
Single Diffraction orSingle Dissociation
Double Diffraction or Double Dissociation
Double Pom. Exchange or Central Dissociation
Single + DoubleDiffraction (SDD)
SD DD DPE/CD SDD
Elastic scattering Total cross sectionT=Im fel (t=0)
OPTICALTHEOREM
gap
JJ, b, J/W ppJJ…ee… exclusive
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DEFINITIONS
MX
dN/d
,t
p’rap-gap=-ln
0s
eEall
i
toweriiCAL
i
1 1
s
Mξ-x X
L
2
1
ln s
22 M
1
dM
dσ
ξ
1
dξ
dσconstant
Δηd
dσ
0t
ln Mx2
ln s
since no radiation no price paid for increasingdiffractive-gap width
pp
MX
pp’
SINGLE DIFFRACTION
DIS-2013, Marseille Diffractive and Exclusive Production at CDF K. Goulianos 5
Forward momentum loss
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
p
p
p’
√s=22 GeV
RENORMALIZATION
Regge
FACTORIZATION BREAKING IN SOFT DIFFRACTION
CDF
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Interpret flux as gap formation probability that saturates when it reaches unity
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EXCLUSIVE Dijet Excl. HiggsTHEORY CALIBRATION
p
p_
}JJ c
Exclusive dijets
PRD 77, 052004 (2008)
PRL 102 , 242001 (2009)
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Exclusive c Exclusive dimuon productionExclusive dimuon production
3 GeV/c2 <M<4 GeV/c2p+p→p++-+p
PRL 102, 242001 (2009)
Several physics processes in this dataset:
__
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Exclusive c Exclusive Exclusive cc→J/→J/(→(→++--)+)+
Allowing EM towers (ET >80MeV)
large increase in the J/ peak &
minor change in the (2s) peak
Evidence for:
c→J/+ production
J/ 286 352 = +66 events
(2s) 3940 = +1 event
d/dy|y=0 = 75 ± 14 nb,
compatible with theoretical predictions160 nb (Yuan 01) 90 nb (KMR01)
Allow extra EM tower
PRL 102, 242001 (2009)
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Exclusive c Exclusive J/Exclusive J/ and and (2s)(2s)J/ producton 243 21 events
d/dy|y=0= 3.92± 0.62 nb
Theoretical PredictionsTheoretical Predictions
2.8 nb [Szczurek07,], 2.8 nb [Szczurek07,], 2.7 nb [Klein&Nystrand04], 2.7 nb [Klein&Nystrand04], 3.0 nb [Conclaves&Machado05], and 3.0 nb [Conclaves&Machado05], and 3.4 nb [Motkya&Watt08].3.4 nb [Motkya&Watt08].
s production347 eventsd/dy|y=0 = 0.54 0.54 ± 0.15 nb R = (2s)/J/= 0.14 ± 0.05In agreement with HERA: R = 0.166 ±
0.012 in a similar kinematic region
J/
(2s)QED continuum
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Exclusive production-2012
PRL 108, 081801 (2012)
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Exclusive and e+e-
events
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Exclusive data vs MC
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Exclusive cross section
14
pb0.41(syst)0.42(stat)2.48
pb1.42
pb0.35
33
GeV5E1,|η|exclγγ
33
GeV5E1,|η|SuperCHIC
33
GeV5E1,|η|SuperCHIC
T
T
T
(MSTW08LO)
(MRST99)
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Exclusive event candidate
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Central Exclusive Poroduction of
+-DETECTOR
NOT USED
NOT UED
use only||=5.4-5.9
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Central Exclusive Production of +-
TRIGGERS Two Central Calorimeter towers (||<1.3) w/E≥0.5 GeV (a very
low threshold) and no energy in BSC (||=5.4-5.9) and in the Forward Plug Calorimeters (||=2.11-3.64 ).
“zero-bias” bunch crossing events with no tracks to study noise/exclusivity cuts.
DATA SETS Recorded 90(22)×106 events at√s=1960 (900) GeV.
PRELIMINARY RESULTS
|y(+-)|<1.0, M+-<0.8 where there is some acceptance at all pT.Notice: no particle ID is (yet) being used and the observed tracks
are assumed to be due to pions (until further notice – stay tuned!).
NEW DATA
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“Empty” events detector noise levels
Detector noise levels: Determined separately for interaction
and no-interaction events Rejected “noise” events below
vertical dashed lines
Empty-event selection Select region of bunch luminosity
with low overlaps and high yied
use data only here
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M+- distributions at 1960 GeV
not-corrected for acceptance
corrected for acceptance
we clearly see f0(980), f2(1270) and f0(1370).
the small but significant peak at 3.1 GeV is understood to be from J/e+e- with masses assumed as m+m-.
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Event ratio of 1960/900 GeV and average PT at 1960 GeV
Ratio of candidates at √s=1960/900 GeV vs M(pair)
Mean pT(pair) in GeV/c as a function of M(pair)
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Comparisons of d/dM events per bin
The structures observed in the mass region of less than ≈1 GeV are under investigation.
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SUMMARY
Reviewed briefly exclusive production at CDF.
Measured exclusive +- production (no particle ID yet, tracks assumed to be due to pions) at √s=900 GeV and √s=1960 GeV with higher statistics than in earlier studies.
Explored the low mass region: found well known structures from AFS at ISR at √s=63 GeV for M
- < 1.5 GeV, and also
features that are not yet understood for M- > 1.5 GeV.
Partial wave analysis currently underway – stay tuned!Thank you for your attention