diffraction @ cdf the future of qcd at the tevatron fermilab, 20-22 may 2004 konstantin goulianos...
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Diffraction @ CDF
The Future of QCD at the Tevatron Fermilab, 20-22 May 2004
Konstantin Goulianos
The Rockefeller University
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 2
CDF Run I results
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 3
Run I
Run #
Dates pb-1 Physics
1-0 1988-89 ~5Elastic,Diffractive& Total x-sections
1-A,B 1992-95~12
0Rapidity Gaps
1-C 1995-96 ~10 Roman Pots
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 4
Run 1-0 (1988-89)Elastic, single diffractive, and total cross sections @ 546 and 1800 GeV
Roman Pot Spectrometers
Roman Pot Detectors Scintillation trigger counters Wire chamber Double-sided silicon strip detector
Results Total cross section tot ~ s Elastic cross section d/dt ~ exp[2’ lns] shrinking forward peak Single diffraction Breakdown of Regge factorization
Additional DetectorsTrackers up to || = 7
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 5
Total & Elastic Cross Sections
The exponential rise of T is a QCDaspect expected in the parton model
(see E. Levin, An Introduction to Pomerons,Preprint DESY 98-120)
yooT ess )(
y sy ln
ytel etsf ),(Im
y sy ln
(Run I-0)
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 6
Unitarity problem: With factorization and std pomeron flux SD exceeds T at
Renormalization: normalize the pomeron flux to unity
Soft Diffraction (Run I-0)
)(Mσξ)(t,fdtdξ
σd 2XpIPIP/p
SD2
KG, PLB 358 (1995) 379
TeV.2s
1dtdξξ)(t,f0.1
ξ
IP/p
0
tmin
~10
2~ sSD
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 7
M2-scalingKG&JM, PRD 59 (1999) 114017
Factorization breaksdown in favor of
M2-scaling
12
2
2 )(M
s
dM
d
renormalization
1
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 8
yy
yt ,2 independent variables:
yoyt
p eetFCyddt
d
2
12
2
)(
Gap probability
Renormalization removes the s-dependence M2-SCALING
QCD Basis for Renormalization
ye 2~ 22ln
minsyssy
y
t
colorfactor
17.0)0(
)(
ppIP
IPIPIP tg
(KG, hep-ph/0205141)
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 9
and Experimentally: KG&JM, PRD 59 (114017) 1999
g=0.20
q=0.04
R=-0.5
fg=gluon fractionfq=quark fraction
λx
1f(x)x
18.03
125.0
8
175.0
121f
1
1f
2
Q
NN cq
cgColor factor:
12.0ww qqgg Pomeron intercept:
104.0,02.017.0
pIP
IPIPIPg
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 10
CDF-IRun-IC Run-IA,B
Forward DetectorsBBC 3.2<<5.9FCAL 2.4<<4.2
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 11
Double Diffraction Dissociation
One central gap
Double Pomeron Exchange
Two forward gaps
SDD: Single+Double Diffraction One forward + one central gap
Soft Central and Double Gaps
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 12
2122
2-1i1
2
51
5
)( yyo
ytp
ii
eetFCdV
dii
Gap probability Sub-energy cross section(for regions with particles)
Generalized Renormalization
ye 2~ 22ln
minsyssy
y
Same suppressionas for single gap!
1y 2y1y 2y
1y 2y
1t 21 yyy 5 independent variables
2t colorfactors
(KG, hep-ph/0205141)
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 13
One-gap cross sections are suppressed Two-gap/one-gap ratios are 17.0
Central & Double-Gap ResultsDifferential shapes agree with Regge predictions
DD SDD DPE
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 14
Soft Gap Survival Probability
0.23GeV)(1800S gapgap/01gapgap/12
0.29GeV)(630S gapgap/01gapgap/12
S =
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 15
Soft Diffraction Conclusions
M2 – scaling
Non-suppressed double-gap to single-gap
ratios
Experiment:
Phenomenology:
Generalized renormalization
Obtain Pomeron intercept and tripe-Pomeron coupling from inclusive PDF’s and color factors
Soft diffraction is understood ! (?)
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 16
Hard Diffraction
Diffractive Fractions
Diffractive Structure Function
Factorization breakdown and restoration
DSF from inclusive PDF’s
Hard diffraction conclusions
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 17
Factorization OK @ Tevatronat 1800 GeV (single energy)
• All SD/ND fractions ~1%• Gluon fraction• Suppression by ~5 relative to HERA gap survival probability ~20%
Diffractive Fractions
15.054.0 gf
gap Xpp
1.45 (0.25)J/
0.62 (0.25)b
0.75 (0.10)JJ
1.15 (0.55)W
Fraction(%)X
SD/ND fraction at 1800 GeVJetJetpp gap
DD/ND gap fraction at 1800 GeV
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 18
Diffractive Structure F‘nXJetJetppp
SD/ND Rates vs • Measure ratio of SD/ND dijet rates as a f’n of
• In LO-QCD ratio of rates equals ratio of structure
fn’s
px
45.0p0p
ND
SD xR)(xR
px
s
eE/ppx
2(3)
1i
iηiT
pqg,p
))(xq)(x(q
C
C)g(xx)(xF pipi
A
Fpppjj
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 19
Breakdown of QCD Factorization
dN/dgap
e*
HERA TEVATRON
dN/dgap
p
ppIPt
),( 22 xQF
),,,( 22 tQF D ),,,( tEF Jet
TDJJ
),( xEF JetTJJ
CDF
H1
p
ppIP
pIP
???
The clue to understanding the Pomeron
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 20
Restoring Diffractive Factorization
R(SD/ND)
R(DPE/SD)
DSF from double-gaps:Factorization restored!DSF from single-gaps
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 21
DSF from Inclusive pdf’s (KG)
Power-law region
max = 0.1xmax = 0.1 < 0.05
xxfx
1)(
g=0.20
q=0. 04
R=-0.5
g =0.5
q =0.3
CAC
xFxF NORM
Q
QQQ
D 1)(1
21
22
2
)(
)(1),(
1),,(
constant:) (noHERA fixedRENORM xRDDISDIS
)(R:(RENORM)TEVATRON
xxSDND
22 QDDIS
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 22
Pomeron Intercept from H1
RENORM
1+
ttIP 1)(
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 23
-dependence: Inclusive vs Dijets
g =0.5
q =0.3
))(xq)(x(q
9
4)g(xx)(xF pipipppjj
0.1)0.9m0.1,1.0(n ξ
1
β
1ξβ,F
mnDjj
Pomeron dominated
constantdξ
dσincl
Pomeron+Reggeon
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 24
Enery Dependence of FJJD
R630/1800 = 1.3±0.2(stat)+0.4/-0.3(syst)
Phenomenological Models:
– RenormalizationPhys. Lett. B 358, 379 (1995).
– Gap survival probability, e.g.Eur.Phys. J. C 21, 521 (2001).
– Soft color interactions Phys. Rev. D 64, 114015 (2001).
R630/1800(predicted) ~ 1.5 - 1.8
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 25
Hard Diffraction Conclusions
Diffraction appears to be a low-x exchange subject to color constraints
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 26
Summary of Run I Results
M2 – scaling
Non-suppressed double-gap to single-gap ratios
Flavor-independent SD/ND ratios
Factorization breakdown and restoration
SOFT DIFFRACTION
Universality of gap prob. across soft and hard diffraction
HARD DIFFRACTION
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 27
Run II Diffractive Program Single Diffraction and Q2 dependence of Fjj
D
Process dependence of FD (W, b,J/ Double Diffraction Jet-Gap-Jet: gap for large fixed jet
Double Pomeron Exchange Fjj
D on p-side vs -pbar
Also:Exclusive central production Dijets, c, low mass states, Higgs(!)(?)…
Other Open to suggestions
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 28
CDF-II Tag leading p-bar @ 0.02 < < 0.1
Reject (retain) 95% of ND (SD)events
detectforwardparticle
s
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 29
MiniPlug Calorimeter
About 1500 wavelength shifting fibers of 1 mm dia. are ‘strung’ through holesdrilled in 36x¼” lead plates sandwiched between reflective Al sheets and guided
into bunches to be viewed individually by multi-channel photomultipliers.
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 30
Artist’s View of MiniPlug
25 in 5.5 in
84 towers
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 31
Q2 dependence of DSF
x),2F(Q
ξ)x,,2(QDFR
~ no Q2 dependence~ flat at HERA~ 1/x0.5 at Tevatron
Pomeron evolves similarly to protonexcept for for renormalizartion effects
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 32
Hard Double Diffraction
jet???gap ΔyΔy Question
gapΔyjetΔy
5%1%/0.2/SR)s(R JGJTEV
JGJLHC
JetGapJetpp
Run I Results
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 33
Exclusive Dijets in DPEInterest in diffractive Higgs production Calibrate on exclusive dijets
pb10534GeV25
pb27265970GeV10
0.8)(RσE jjjjexcl
DPEjetT
Upper limit for excl DPE-jjconsistent with theory
Dijet mass fraction
X
conejj
jj M
MR
no peak!
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 34
Search for Exclusive c @CDFpγ)J/ψ(χppp c
• Events are triggered on dimuons• Select muons with PT>1.5 GeV, ||< 0.6• Reject cosmic rays using time of flight information• Select events in J/ mass window
10 c candidates
No positive identification of c events Cross section upper limit comparable to KMR prediction
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 35
Merits/Problems/NeedsMerits of CDF Run II diffractive program Measuring with calorimeters full acceptance
overlap rejection BSC gap triggers can take data at high luminosities
But:
BSC gap rejects some diffractive events from MP spillover Useful rates too low for many processes, e. g. exclusive b-bbar
Need:
Low luminosity runs for calibrations:-roman pot vs -calorimeter BSC gap trigger vs roman pot trigger
Also need:
$$$ to instrument MPs from current 84 to all 256 channels for EM/hadron discrimination and better jet definition
Fermilab 20-22 May 2004 The Future of QCD: Diffraction @CDF K. Goulianos 36
CONCLUSION
Run II CDF has a comprehensive Run II diffractive program Modest upgrades & special runs are desirable Full MiniPlug instrumentation Low luminosity (~1030) runs for calibrations Data run at 630 GeV
Beyond Run II Can think of improvements, but of no compelling diffractive physics that cannot be done in Run II