Diffractive Structure Functions and Exclusive Production from CDF to LHC Konstantin Goulianos The...
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Transcript of Diffractive Structure Functions and Exclusive Production from CDF to LHC Konstantin Goulianos The...
Diffractive Structure Functionsand Exclusive Production
from CDF to LHC Konstantin Goulianos
The Rockefeller Universityand the CDF Collaboration
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 2
Contents
Introduction Elastic and total cross sections Soft diffraction Hard diffraction Exclusive Production
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 3
p-p InteractionsDiffractive:
Colorless exchange with vacuum quantum numbers
Non-diffractive:Color-exchange
Incident hadrons retain their quantum numbersremaining colorless
pseudo-DECONFINEMENT
Incident hadrons acquire colorand break apart
CONFINEMENT
POMERON
Goal: understand the QCD nature of the diffractive exchange
rapidity gap
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 4
Diffractive pp Processes
Elastic scattering Total cross section
SD DD DPE SDD=SD+DD
T=Im fel (t=0)
OPTICALTHEOREM
GAP
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 5
CDF Run 1-0 (1988-89)Elastic, diffractive, and total cross section @ 546 and 1800 GeV
Roman Pot Spectrometers
Roman Pot Detectors Scintillation trigger counters Wire chamber Double-sided silicon strip detector
Roman Pots with Trackers up to || = 7
CDF-I
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 6
CDF-IRun-IC Run-IA,B
Forward DetectorsBBC 3.2<<5.9 FCAL 2.4<<4.2
beam
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 7
CDF-II ROMAN POT DETECTORS
BEAM SHOWER COUNTERS:Used to reject ND events
MINIPLUG CALORIMETER
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 8
The MiniPlugs @ CDF
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 9
ELASTIC AND TOTAL CROSS SECTIONS
@ Tevatron: CDF and E710/811 use luminosity independent method
Optical theorem
Alert: background Ninel yields small T
undetected Ninel yields large T
inelelt
elT
inelelTt
elT
NNdt
dN
NNLdt
dN
L
1
1
16
1~&
1
11~
02
02
2
optical theorem
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 10
Total Cross Sections: Regge fitCMG fit:
Covolan, Montagna, GoulianosPLB 389 (1995) 176
Simultaneous Regge fit to pp, p, and Kp x-sections using the eikonal approach to ensure unitarity
S
= 1.104 +/- 0.002
LHC = 115
mb @14 TeV
Bornlevel
DL
E710CDF
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 11
T: other approaches
T (LHC) = 107.3 ± 1.2 mb
eg, M. Block, arXiv:hep-ph/0601210 (2006)
fit data using analyticity constraintsM. Block and F. Halzen, Phys. Rev. D 72, 036006
Recall CMG Regge fit: 115 mb
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 12
T and -values from PDG
E710
= ratio of real/imaginary partsof elastic scattering amplitude at t=0
E811
CDFCDF and E710/811 disagree
CDF & UA4
T
optical theoremIm fel(t=0)
dispersion relationsRe fel(t=0)
E811
N. Khuri and A. Martin: measuring at the LHC
tests discreteness of space-time
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 13
SOFT DIFFRACTIONKey words:
renormalization
scaling
QCD
multi-gap
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 14
Regge theory SD exceeds T at
Renormalization Pomeron flux integral (re)normalized to unity
Renormalization )(Mσξ)(t,f
dtdξ
σd 2XpIPIP/p
SD2
KG, PLB 358 (1995) 379
TeV.2s
1dtdξξ)(t,f0.1
ξ
IP/p
0
tmin
2~ sSD
Pomeron flux
Factorization
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 15
A Scaling Law in Diffraction
KG&JM, PRD 59 (1999) 114017
Factorization breaks down so as to ensure M2-scaling!
12
2
2 )(M
s
dM
d
renormalization
1
Independent of S over 6 orders of magnitude in M2 !
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 16
The QCD Connection
ytel etsf ),(Im
y sy ln
The exponential rise of T(y’) is dueto the increase of wee partons with y’
(E. Levin, An Introduction to Pomerons,Preprint DESY 98-120)
ses oy
oT )(y
sy lnTotal cross section:power law increase versus s
Elastic cross section:forward scattering amplitude
s
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 17
yy
yt ,2 independent variables:
yoyt
p eetFCyddt
d
222
)(
Gap probability
Renormalization removes the s-dependence SCALING
Single Diffraction in QCD
ye 2~ 22ln
minsyssy
y
t
colorfactor
(KG, hep-ph/0205141)
ε12
2ε
REGGE2 )(M
s
dM
dσ
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 18
Multi-gap Renormalization
ye 2~ 22ln
minsyssy
y
Same suppressionas for single gap!
1y 2y1y 2y
1y 2y
1t 21 yyy 5 independent variables
2t
2122
2-1i1
2
51
5
)( yyo
ytp
ii
eetFCdV
dii
Gap probability Sub-energy cross section(for regions with particles)
colorfactors
(KG, hep-ph/0205141)
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 19
Double Diffraction Dissociation
One central gap
Double Pomeron Exchange
Two forward gaps
SDD: Single+Double Diffraction One forward + one central gap
Central and Double Gaps @ CDF
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 20
One-gap cross sections are suppressed Two-gap/one-gap ratios are 17.0
Central & Double-Gap CDF Results
Differential shapes agree with Regge predictions
DD SDD DPE
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 21
Gap Survival Probability
0.23GeV)(1800S gapgap/01gapgap/12
0.29GeV)(630S gapgap/01gapgap/12
S =
Results similar to predictions by:Gotsman-Levin-MaorKaidalov-Khoze-Martin-RyskinSoft color interactions
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 22
HARD DIFFRACTION Diffractive fractions Diffractive structure function factorization breakdown Restoring factorization Q2 dependence t dependence Hard diffraction in QCD
dN/d
JJ, W, b, J/
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 23
All ratios ~ 1% ~ uniform suppression
~ FACTORIZATION !
Diffractive Fractions @ CDF
gap)( Xpp
1.45 (0.25)J/
0.62 (0.25)b
0.75 (0.10)JJ
1.15 (0.55)W
Fraction(%)Fraction:SD/ND ratioat 1800 GeV
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 24
The diffractive structure function at the Tevatron is suppressed by a factor of ~10 relative to expectation from pdf’s measured by H1 at HERA
Similar suppression factor
as in soft diffraction relative to Regge expectations!
Diffractive Structure Function:Breakdown of QCD Factorization
CDF
H1
= momentum fraction of parton in Pomeron
Using preliminary pdf’s from
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 25
Restoring QCD Factorization
R(SD/ND)
R(DPE/SD)DSF from two/one gap:factorization restored!
The diffractive structure function measured on the proton side in events with a leading antiproton is NOT suppressed relative to predictions
based on DDIS
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 26
Diffractive Structure Function:Q2 dependence
ETjet ~ 100 GeV !
Small Q2 dependence in region 100 < Q2 < 10,000 GeV2
Pomeron evolves as the proton!
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 27
Diffractive Structure Function:t- 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 < 4,500 GeV2
across soft and hard diffraction!
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 28
valence quarks
antiproton
x=
Hard Diffraction in QCD
proton
deep sea
Derive diffractivefrom inclusive PDFsand color factors
antiproton
valence quarks
p
p
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 29
EXCLUSIVE PRODUCTION
H
Measure exclusive jj & Calibrate predictions for H production rates @ LHC
Bialas, Landshoff,Phys.Lett. B 256,540 (1991)Khoze, Martin, Ryskin,Eur. Phys. J. C23, 311 (2002); C25,391 (2002);C26,229 (2002)C. Royon, hep-ph/0308283B. Cox, A. Pilkington,PRD 72, 094024 (2005)OTHER…………………………
Search for exclusive dijets:Measure dijet mass fraction
Look for signal as Mjj 1
rscalorimeteallM
MR
X
jjjj
Search for exclusive 3 candidate events found 1 (+2/-1) predicted from ExHuME MC* background under study
* See talk by V. Khoze
KMR: H(LHC) ~ 3 fbS/B ~ 1 if M ~ 1 GeVClean discovery channel
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 30
Exclusive Dijet Signal
b-tagged dijet fraction Dijet fraction – all jets
Exclusive b-jets are suppressedby JZ= 0 selection rule
Excess over MC predictions at large dijet mass fraction
DIJETS
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 31
RJJ(excl): Data vs MC
Shape of excess of events at high Rjj
is well described by both models
ExHuME (KMR): gggg process uses LO pQCD
Exclusive DPE (DPEMC) non-pQCD based on Regge theory
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 32
jjexcl: Exclusive Dijet Signal
COMPARISONInclusive data vs MC @ b/c-jet data vs inclusive
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 33
JJexcl : x-section vs ET(min)
Comparison with hadron level predictions
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 34
JJexcl : cross section predictionsExHuME Hadron-Level Differential Exclusive Dijet Cross Section vs Dijet Mass (dotted/red): Default ExHuME prediction
(points): Derived from CDF Run II Preliminary excl. dijet cross sections
Statistical and systematic errors are propagated from measured cross section uncertainties using ExHuME Mjj distribution shapes.
HERA&LHC, 12-16 March 2007 Diffraction from CDF to LHC K. Goulianos 35
Summary
TEVATRON – what we have learnt M2 – scaling Non-suppressed double-gap to single-gap ratios Pomeron: composite object made up from underlying pdf’s subject to color constraints
LHC - what to do Elastic and total cross sections & -value High mass (4 TeV) and multi-gap diffraction Exclusive production (FP420 project) Reduced bgnd for std Higgs to study properties Discovery channel for certain Higgs scenarios