High Energy Physics Seminar
University of Connecticut7 February 2005
Konstantin Goulianos
The Rockefeller University
QCD ASPECTS OF HADRONIC DIFFRACTION
CDF results Comparison with HERA QCD aspects Tev2LHC
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 2
What is Dark Energy?
* * ** * *
H He
E
M
* * ** * *
H He
E
M
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 3
Rapidity Gaps
Gaps are exponentially suppressed
From Poisson statistics:
dy
dneyP y )(
(=particle density in rapidity space)
Rapidity gaps are formed bymultiplicity fluctuations.
Non-diffractive interactions
Bj, PRD 47 (1993) 101: regions of (pseudo)rapidity devoid of particles
ε122
0t M
1~
dM
dσΔy2εe~Δyd
dσ
2lnlnln Msy
Rapidity gaps at t=0 grow with y.Diffractive interactions
pp /
2: negative particle density!
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 4
Forty Years of Diffraction
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/ HERA: QCD factorization breakdown
21st C Multigap diffraction: restoration of factorizationIdeal for diffractive studies @ LHC
http://physics.rockefeller.edu/dino/my.html
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 5
The First 20 Years The First 20 Years
KG, Phys. Rep. 101 (1983) 171
XLL/PΔPξ
1
~d
d
constantyd
dσ
M
1~
dM
dσ22
POMERON: color singlet w/vacuum quantum numbers
s
M
p
Δpξ
2
L
L y
y
2ln M
slnln
y025.0dMdt
σd2
2
t
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 6
The Last 20 Years
93(2004)141601
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 7
valence quarks
antiproton
x=
Diffraction in QCD
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
pp
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 8
CDF in Run I-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
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 9
Regge Theory
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 10
Unitarity problem: With factorization and std pomeron flux SD exceeds T at
Renormalization: normalize the pomeron flux 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
~10
2~ sSD
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 11
A Scaling Law in Diffraction
KG&JM, PRD 59 (1999) 114017
Factorization breaksdown in favor of
M2-scaling
12
2
2 )(M
s
dM
d
renormalization
1
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 12
The QCD Connection
ytel etsf ),(Im
y sy ln
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
Elastic cross sectionforward scattering amplitude
s
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 13
yy
yt ,2 independent variables:
yo
ytp eetFC
yddt
d
222
)(
Gap probability
Renormalization removes the s-dependence SCALING
QCD Basis of Renormalization
ye 2~ 22ln
minsyssy
y
t
colorfactor
17.0)0(
)(
ppIP
IPIPIP tg
(KG, hep-ph/0205141)
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 14
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
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 15
Run-I A,B: Rapidity Gap Studies
Forward DetectorsBBC 3.2<<5.9FCAL 2.4<<4.2
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 16
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
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 17
2122
2-1i1
2
51
5
)( yyo
ytp
ii
eetFCdV
dii
Gap probability Sub-energy cross section(for regions with particles)
Multigap 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)
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 18
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
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 19
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
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 20
Soft Diffraction Summary
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
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 21
SOFT DIFFRACTION
Hard Diffraction @ CDF HARD DIFFRACTION
Additional variables: (x, Q2)
seExjet
T
jetBj /
22 )(, jetTEQx
dN/d
=PL/PL =fractional momentum loss of scattered (anti)proton
Variables: (, t) or (,
t)
MX
=-lnt
dN/d
ln MX2
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 22
All fractions ~ 1% Factorization ~ OK @ Tevatron
at fixed c.m.s. energy.
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(%)X
SD/ND fraction at 1800 GeV
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 23
Diffractive DIS @ HERA
),(1
),,( 221
2)3(2 QQ xFxF D
eQ2*
p
jet
reorganize
J. Collins: Factorization should hold
e*
tp
IP
Pomeron exchange Color reorganization
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 24
Inclusive vs Diffractive DIS
CCF
Q
QQD
1212)3(
2
1
)()(
)(1),,(
2
P(0)-1(q)/2
F2 ~ x
q
KG, “Diffraction: a New Approach,” J.Phys.G26:716-720,2000 e-Print Archive: hep-ph/0001092
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 25
diff/incl DIS at HERA
At fixed x:flat Q2-dependence
At fixed Q2:flat x-dependence
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 26
Diffractive Dijets @ Tevatron
),/(1
),,( 22
21 QQ xFxF D
pjet
reorganizep
jet
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 27
CDF-ICRun-IC Run-IA,B
Forward DetectorsBBC 3.2<<5.9FCAL 2.4<<4.2
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 28
Roman Pot tracking
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 29
Diffractive Structure F‘n @CDF XJetJetppp
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
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 30
FDJJ(,Q2) @ Tevatron
C
sx
CF
Q
QQD
2122111
)/(
)(1),,(
)(
22
2
εε
2sβ
1~
β
xξ1
ξ 211
renorm sβξ
dξN
minmin
min
)2(
)(1
121
~R2
RENORM
x
QsxSD
ND
4.02.0 xg
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 31
Tevatron vs HERA:Factorization Breakdown
dN/dgap dN/dgap
p
ppIP
CDF
H1
p
ppIP
e*
tp
IP
Predicted in KG, PLB 358 (1995) 379
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 32
Restoring Factorization
R(SD/ND)
R(DPE/SD)DSF from two/one gap:factorization restored!
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 33
CDF-II Tag leading p-bar @ 0.02 < < 0.1
Reject (retain) 95% of ND (SD)events
detectforwardparticle
s
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 34
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.
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 35
Artist’s View of MiniPlug
25 in 5.5 in
84 towers
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 36
Diffractive dijets
=alltowers)ET e
s
momentum loss fraction of pbar
Approx. flat at <0.1
const
overlap events
SD region
MP energy scale: ±25% →Δlogξ = ±0.1RP acceptance (0.03<ξ< 0.1) ~ 80% (Run I)
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 37
: RP vs calorimeter
overlap events
signal region
cal distribution for slice of RP
from RP
cal = (0.94 ± 0.03)
RP
/mean ~ 30%
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 38
Q2-dependence of SD/ND ratio
No appreciable Q2 dependence
within 100 < Q2 < 10,000 GeV2
Pomeron evolves similarly to proton
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 39
Exclusive Dijets in DPEInterest in diffractive Higgs production Calibrate on exclusive dijets
Dijet mass fraction
X
conejj
jj M
MR
no peak!pb10534GeV25
pb27265970GeV10
0.8)(RσE jjjjexcl
DPEjetT
Upper limit for excl DPE-jjconsistent with theory: KMR 60 pb @ 25<ET
J<35 GeV
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 40
Gap Between Jets
jet???gap ΔyΔy Question
gapΔyjetΔy
5%1%/0.2/SR)s(R JGJTEV
JGJLHC
JetGapJetpp
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 41
CDF2LHC
TOPIC STATUS
(Q2, t) dependence of DSF close to ready
Exclusive c production close to ready
Low mass states in DPE need good trigger
Exclusive b-bbar production in DPE need b-trigger
-dependence of DSF need low lum run
Jet-gap-Jet w/jets in miniplugs need low lum run
compositeΔyΔy
BFKLΔyΔyjetgap
jetgap
gapΔyjetΔy
UC seminar, 7 Feb 2005 QCD Aspects of HadronicDiffraction K. Goulianos 42
Summary
M2 – scaling
Non-suppressed double-gap to single-gap ratios
Flavor-independent SD/ND ratio
Little or no Q2-dependence in SD/ND ratio
SOFT DIFFRACTION
Universality of gap prob. across soft and hard diffraction Pomeron evolves similarly to proton
HARD DIFFRACTION
Diffraction appears to be a low-x partonic exchange subject to color constraints