k. goulianos the rockefeller university eds 2005 15-20 may 2005 chateau de blois, france twenty...
Post on 19-Dec-2015
214 views
TRANSCRIPT
K. GoulianosThe Rockefeller University
EDS 200515-20 May 2005
Chateau de Blois, France
Twenty Years of Diffractionat the Tevatron
http://physics.rockefeller.edu/dino/my.html
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 2
-p Interactions
Diffractive:
vacuum exchange
Protons retain theirquantum numbers
Non-diffractive:
color exchange
Protons acquire colorand break apart
p
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 3
Why StudyParticle Diffraction?
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 4
Asymmetric Fireworks?Po’< Po
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 5
Non-perturbative QCD
THEORY
Important for understanding hadron structure and quark confinement
Need to develop new mathematical methods
Diffraction offers an arena on which to confront non-pQCD
pure thinking!
experiment
phenomenology
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 6
1960’s BNL: first observation of pp -> pX
1970’s Fermilab fixed target, ISR, SPS Regge theory & factorization
Review: KG, Phys. Rep. 101 (1983) 169
1980’s UA8: diffractive dijets hard diffraction
1990’s Tev Run-I: Regge factorization breakdownTev vs HERA: QCD factorization breakdown
21st C Multigap diffraction: restoration of factorizationIdeal for diffractive studies @ LHC
Forty Years of DiffractionTwenty Years at the Tevatron
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 7
CDF 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
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 8
Run 1-0 results in perspective
KG, PLB 358 (1995) 379
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 9
CDF Run 1 (1992-1995)
Run-IC Run-IA,B
Forward DetectorsBBC 3.2<<5.9FCAL 2.4<<4.2
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 10
Diffraction @ CDF in Run I
93(2004)141601
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 11
All ratios ~ 1% ~ uniform suppression
~ FACTORIZATION
Diffractive Fractions @ CDF
gap)( XHdpp
1.45 (0.25)J/
0.62 (0.25)b
0.75 (0.10)JJ
1.15 (0.55)W
Fraction(%)Hd
Fraction:SD/ND ratioat 1800 GeV
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 12
Tevatron vs HERA:Breakdown of QCD Factorization
CDF
H1
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 13
Multigap Diffraction
1y 2y1y 2y
1y 2y
(KG, hep-ph/0205141)
y
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 14
Elastic and Total Cross Sections
QCD expectations
ytel etsf ),(Im
y sy ln
Elastic cross section:forward scattering amplitude
The exponential rise of T(y’) is dueto the increase of wee partons with y’
(see E. Levin, An Introduction to Pomerons,Preprint DESY 98-120)
yooT ess )(
y sy ln
Total cross section:power law rise with energy
s
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 15
Gap probability MUST be normalized to unity!
Single Diffraction
yy
yt ,2 independent variables:
t
colorfactor
17.0)0(
)(
ppIP
IPIPIP tg
yo
ytp eetFC
yddt
d
222
)(
gap probability sub-energy x-section
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 16
Single diffraction (re)normalized
yo
ytpgap eetFCN
yddt
d
222
)(
s
sCdtydtyPsN s
gaptygap ln),()(
2
,1
tybys eseCyddt
d )2()(ln2
0ln
No unitarity problem after eikonalization of the elastic amplitude
Grows slower than lns
),( tyPgap
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 17
Total Single Diffractive x-Section
Unitarity problem: Using factorization and std pomeron flux SD exceeds T at Renormalization: Normalize the Pomeron flux to unity
)(sσξ)(t,fdtdξ
σdpIPIP/p
SD2
KG, PLB 358 (1995) 379
TeV.2s
1dtdξξ)(t,f0.1
ξ
IP/p
0
tmin
2~ sSD
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 18
The Factors 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
λ
/sxs~dxxf
1
1)(
CTEQ5L
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 19
Multigap Cross Sections
ssty ln/2~,
Same suppressionas for single gap!
2122
2-1i1
2
51
5
)( yyo
ytp
ii
eetFCdV
dii
Gap probability Sub-energy cross section(for regions with particles)
1y 2y1y 2y
1y 2y
1t 21 yyy 5 independent variables2t color
factors
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 20
Central and Two-Gap CDF Results
One-gap cross sections are suppressed Two-gap/one-gap ratios are 17.0
Agreement with renormalized Regge predictions
DD SDD DPE
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron 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
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 22
),(),(),,( 22
22)3(2
2 QQQ xFmfxF hadronqD
Diffractive DIS @ HERA
eQ2*
p
jet
reorganize
Factorization holds: J. Collins
e*
tp
IP
Pomeron exchange Color reorganization
Brodsky et al. rescattering?
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 23
Inclusive vs Diffractive DIS
Rq Q
Q
QRqRq Q
Q
Rq
DCC
F Q, ,1
,,1
05.02)3(2
2
2
22
2 1
)(
1),,(
P(0)-1(q)/2
F2 ~ x
q
g=0.20
q=0. 04
R=-0.5
KG, “Diffraction: a New Approach,” J.Phys.G26:716-720,2000 e-Print Archive: hep-ph/0001092
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 24
Diffractive Dijets @ Tevatron
),/(1
),,( 22
21 QQ xFxFsoft
D
pjet
reorganizep
jet
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 25
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
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 26
SD/ND Dijet Ratio vs xBj@ CDF
(x)F
(x)FR(x) ND
jj
SDjj
0.035 < < 0.095
Flat dependence
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 27
Restoring Factorization @ Tevatron
R(SD/ND)
R(DPE/SD)
DSF from two/one gap:factorization restored!
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 28
Gap Between Jets
5%0.2
1%
S
R)s(R
JGJTEVJGJ
LHC
JetGapJetpp
1%/)s(R JGJTEV
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 29
Gap Between Jets
jet???gap ΔyΔy Question
gapΔyjetΔy
JetGapJetpp
Is the diffractive exchange BFKL-likeor simply a color rearrangement?
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 30
valence quarks
antiproton
x=
Low-x and Diffraction
proton
)or(1
)( xxfx
g=0.20
q=0. 04
R=-0.5
g=0.5
q=0.3
SOFT HARD
deep sea
Derive diffractivefrom inclusive PDFsand color factors
antiproton
valence quarks
p
p
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 31
Run 2 CDF Diffractive Program
Single Diffraction and Q2 dependence of Fjj
D
Process dependence of FD (W, J/ Double Diffraction Jet-Gap-Jet: gap for fixed large jet
Double Pomeron Exchange Fjj
D on p-side vs -pbar
Also:Exclusive central production Dijets, c
Other Tev4LHC issues
EDS 2005, 15-20 May 2005 Twenty Years of Diffraction at the Tevatron K. Goulianos 32
Summary
Diffraction is a low-x QCD phenomenon subject to color constraints. Multigap processes offer the opportunity to study diffraction without complications arising from rapidity gap survival issues. Regularities observed in Run 1 at the Tevatron and in results obtained at HERA paint a picture of the Pomeron as a composite object constructed from the underlying inclusive pdf’s of the (anti)proton. This picture could be further clarified and advanced to a theory by studies at the LHC.