Download - Diffraction from HERA and Tevatron to LHC
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 1
Konstantin GoulianosThe Rockefeller University
Workshop on physics with forward proton taggersat the Tevatron and LHC
14-16 December 2003, Manchester, UK
Diffraction from HERA and Tevatron to LHCDiffraction from HERA and Tevatron to LHC
results theory predictions
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 2
Soft diffraction Elastic and total cross sections M2-scaling Soft diffraction cross sections Multigap diffraction
Diffractive DIS at HERA Derive F2D3 Explain flat ratio of F2D3 / F2 Explain rise of ( or IP) with Q2
Hard diffraction at the Tevatron Explain ratio of Fjj(SD) / Fjj(ND) – magnitude and shape! Double-gap hard diffraction
Diffraction at the LHC Soft and hard single and multigap diffraction
Topics Topics
Determine: triple-pomeron coupling
pomeron intercept diffractive cross section
using soft parton densities
Predict from hard plus soft
parton densities
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 3
Elastic scattering Total cross section Diffraction
PRD PRL PRL PRL50 (1994) 5535 87 (2001)141802 submitted 91(2003)011802
SOFT diffraction
HARD diffraction
Control sample
W 78 (1997) 2698 JJ 74 (1995) 855 JJ 85 (2000) 4217
JJ 79 (1997) 2636 JJ 80 (1998) 1156
b-quark 84 (2000) 232 JJ 81 (1998) 5278
J/ 87 (2001) 241802
JJ 84 (2000) 5043
JJ 88 (2002) 151802
with roman pots
PRL reference
PRD 50 (1994) 5518
PRD 50 (1994) 5550
Diffraction at CDF in Run IDiffraction at CDF in Run I 16 papers
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 4
Two (most) important resultsTwo (most) important results
45.0
)(
)()( x
xF
xFxR ND
jj
SDjj
jj
KG&JM, PRD 59 (1999) 114017
122 )(
1
MdM
d
M2SCALING POWER LAW
CDF, PRL 84 (2000) 5043
Soft Diffraction Hard Diffraction
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 5
Soft Double Pomeron ExchangeSoft Double Pomeron Exchange
ieEs
iTp
particlesall
1
Roman Pot triggered events
0.035 < -pbar < 0.095
|t-pbar| < 1 GeV 2
-proton measured using
Data compared to MC based
on Pomeron exchange with
Pomeron intercept =0.1
Good agreement over 4 orders of magnitude!
2pbar
pbar
GeV1||
095.0035.0
GeV1800
t
s
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 6
Total Cross SectionTotal Cross Section
t exhibits universal rise with energy
the falling term at low energies has
NOTHING to do with this rise!
POWER LAW behavior: y
os
opIPt ees ln2 )0(
t=0 elastic scattering amplitude
ytel etyf )(),(Im
Parton model: # of wee partons grows exponentially
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 7
Single Diffraction VariablesSingle Diffraction Variables SOFT DIFFRACTION HARD DIFFRACTION
=PL/PL fractional momentum loss of scattered hadron
Variables: (, t) or (, t)
Additional variables: (x, Q2)
seExjet
T
jetBj /
x
dN/d
=-ln
t
dN/d
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 8
Factorization & (re)normalization
Soft Single Diffraction Phenomenology
y
y
'y
sln2ln XM
ysy ln
XM
)0(
)(
pIP
IPIPIP tg
yo e 22 )( yt
p etFC
COLORFACTOR
Gap probability:Normalize to unity
KG, PLB 358 (1995) 379
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 9
The factors and The factors and
18.03
125.0
8
175.0
1
1
1 02
2
Q
cq
cg N
fN
f
Experimentally:
02.017.0pIP
IPIPIPg
Theoretically:
KG&JM, PRD 59 (114017) 1999
xxfx
1)(
g=0.20
q=0.0412.0ww qqgg
R=-0.5
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 10
2s
X)pp(p)pp( Total cross sectionKG, PLB 358 (1995) 379
Differential cross sectionKG&JM, PRD 59 (114017) 1999
2~ s
12
2
2 )(M
s
dM
d
REGGE
122 )(
1
MdM
d
RENORM
s-independent Differential shape agrees with Regge Normalization is suppressed by factor Renormalize Pomeron flux factor to unity M2 SCALING
Soft Single Diffraction DataSoft Single Diffraction Data
Regge
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 11
Double Diffraction Dissociation
One central gap
Double Pomeron Exchange
Two forward gaps
SDD: Single+Double Diffraction Forward + central gaps
Central and Double GapsCentral and Double Gaps
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 12
colorfactor
1y 2y1y 2y
1y 2y
2t1t 21 yyy 5 independent variables
2122
2-1i1
2
51
5
)( yyo
ytp
ii
eetFCdV
dii
Gap probability Sub-energy cross section(for regions with particles)ye 2~Integral 2~ s
Renormalization removes the s-dependence SCALING
Two-Gap Diffraction (hep-ph/0205141)Two-Gap Diffraction (hep-ph/0205141)
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 13
Differential shapes agree with Regge predictions
One-gap cross sections require renormalization
DD SDD DPE
Two-gap/one-gap ratios are 17.0
Central and Double-Gap CDF ResultsCentral and Double-Gap CDF Results
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 14
Multigap variables Parton model amplitude rapidity gap regions color factor = 0.17 particle cluster regions also: t-across gap centers of floating gap/clusters
Soft Diffraction SummarySoft Diffraction Summary
iy
jy
it ji ,
ytty ef
)(),(
Differential cross section jjii
yo
ytp
ii
eetFCdV
d
n2
gaps-i1
2
var
var
)(
Sub-energy cross sectionNormalized gap probability
form factor for surviving nucleon color factor: one for each gap
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 15
F2(x,Q2) = c x-
F2 from Compton analysis (H1)(Q2) versus Q2
[from the talk of E. Tassi @ Small-x and Diffraction 2003, Fermilab]
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 16
Diffractive DIS @ HERA Diffractive DIS @ HERA
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
xFxFQ
QQQ
D 1)(1
221
232 2
2
)(
)(1),(
1),,(
constant),(
),,( fixed12
2
232
A
xF
xFR
Q
QD
SDND )(2 2
QDDIS
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 17
F2D3(xIP,x,Q2)/F2(x,Q2)F2
D3(xIP,x,Q2)/F2(x,Q2)
At fixed xIP: F2
D3(xIP ,x,Q2) evolves as F2(x,Q2)independent of the value of x
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 18
Pomeron Intercept in DDISPomeron Intercept in DDIS
1+()/2
1+
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 19
)(DJJF
Test Regge factorizationTest QCD factorization
suppressed at the Tevatron
relative to extrapolationsfrom HERA parton densities
mnDJJ CF ),(Regge factorization holds
exchangePomeron1m
Diffractive Dijets @TevatronDiffractive Dijets @Tevatron
H1-2002
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 20
Rjj(x) @TevatronRjj(x) @Tevatron
)(
)()(
xF
xFxR ND
jj
SDjj
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 21
Rjj=FjjSD/Fjj
ND
sx
MdA jj
max
21.0
min1
)(/1
Power-law region
max = 0.1 < 0.05
xxfx
1)(
g=0.20
q=0. 04
R=-0.5
g =0.5
q =0.3
CAC
xFxFQ
NDQ
SD 1
RENORM
)(12
12
2
2
)(
)(1),(
1),,(
x
AR jj
11
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 22
RENORM prediction of R(x) vs dataRENORM prediction of R(x) vs data
CDF data
RENORM prediction
exp-syst-errors
Ratio of diffractive to non-diffractivestructure functions is predicted from PDF’sand color factors with no free parameters.
Fjj() correctly predicted
Test: processes sensitive to quarks will have more flat R(x) – diff W?
R(x)
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 23
HERA vs TevatronHERA vs Tevatron
C
sx
MF jj
QD
1max
2TEVATRON2 1
)(),,(
(re)normalized gap probability
CF Q
D 1
HERA2 176.0),,(
Pomeron flux
RENORM PREDICTIONS
HERA Tevatron Tev/HERAeffective -- 0.55 --Normalization 0.76 0.042 0.06R(x)=FD(x)/F(x) flat x-(eff ~ x-0.5
_eff = [(Q2)]/2 ~ 0.2 -- --
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 24
Another issueQCD evolution
No appreciable ET2 dependence observed within 100 < ET2 < 1600 GeV2
Rjj(xBj) vs Q2
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 25
(not detected)
R(SD/ND)
R(DPE/SD)
Test of factorization
equal?
Factorization breaks down,
but see next slide!
The second gap is less suppressed!!!
Dijets in Double Pomeron ExchangeDijets in Double Pomeron Exchange
SDND
DPESD RR 5
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 26
DSF: Tevatron double-gaps vs HERADSF: Tevatron double-gaps vs HERA
The diffractive structure function derived from double-gapevents approximately agrees with expectations from HERA
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 27
SUMMARYSoft and hard conclusions
Soft Diffraction
Hard Diffraction Pay a color factor for each gap
Use reduced energy cross section
Get gap size from renormalized Pgap
Diffraction is an interaction between low-x partons subject to color constraints
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Manchester 14-16 Dec 2003 Diffraction from HERA and Tevatron to LHC K. Goulianos 28
Inclusive Diffractive Higgs at the LHCInclusive Diffractive Higgs at the LHC
D(LHC) ~ 2 * ND (Tevatron)
=> (0.17)2 * 1 pb = 30 fb
p+p p-gap-(H+X)-gap-p
TevatronLHC ss lnln