Predictions of Diffraction at the LHC Compared to Experimental
ResultsKonstantin Goulianos The Rockefeller University
1
http://physics.rockefeller.edu/dino/my.html
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos
International Conference on New Frontiers in Physics (ICNFP-2013)Aug 28 – Sep 5, 2013, Kolymbari, Crete, Greece
http://indico.cern.ch/event/icnfp2013
Total pp cross section: predicted in a unitarized parton model approach, which does not employ eikonalization and does not depend on the -value.
Diffractive cross sections: SD - single dissociation: one of the protons dissociates. DD - double dissociation: both protons dissociate. CD – central diffraction: neither proton dissociates, but there is
central diffractive production of particles. Triple-Pomeron coupling: uniquely determined.
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 2
This is an updated version of a talk presented at EDS-2013.
CONTENTS
DIFFRACTION IN QCD
Diffractive events
Colorless vacuum exchange
-gaps not suppressed
Non-diffractive events
color-exchange -gaps exponentially suppressed
POMERON
Goal: probe the QCD nature of the diffractive exchange
rapidity gap
p p p p
p
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 3
DEFINITIONS
MX
dN/d
,t
p’rap-gap
=-ln0s
eEΣξ
iηtower-iT
all1iCAL
s
M2Xξ1- Lx
ln s
22 M
1
dM
dσ
ξ
1
dξ
dσconstant
Δηd
dσ
0t
ln Mx2
ln s
since no radiation no price paid for increasingdiffractive-gap width
pp
MX
pp’
SINGLE DIFFRACTION
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 4
Forward momentum loss
DIFFRACTION AT CDF
Single Diffraction orSingle Dissociation
Double Diffraction or Double Dissociation
Double Pom. Exchange or Central Dissociation
Single + DoubleDiffraction (SDD)
SD DD DPE/CD SDD
Elastic scattering Total cross sectionT=Im fel (t=0)
OPTICALTHEOREM
gap
JJ, b, J/W ppJJ…ee… exclusive
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 5
Basic and combined diffractive processes
Basic and combineddiffractive processes
4-gap diffractive process-Snowmass 2001- http://arxiv.org/pdf/hep-ph/0110240
gap
SD
DD
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 6
KG-PLB 358, 379 (1995)
Regge theory – values of so & gPPP?
Parameters: s0, s0' and g(t) set s0‘ = s0 (universal IP ) determine s0 and gPPP – how?
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 7
(t)=(0)+′t (0)=1+
A complicatiion… Unitarity!
A complication … Unitarity!
sd grows faster than t as s increases unitarity violation at high s
(similarly for partial x-sections in impact parameter space)
the unitarity limit is already reached at √s ~ 2 TeV !
need unitarization
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 8
Factor of ~8 (~5)suppression at √s = 1800 (540) GeV
diffractive x-section suppressed relative to Regge prediction as √s increases
see KG, PLB 358, 379 (1995)
1800
GeV
540
GeV
M,t
p
p
p’
√s=22 GeV
RENORMALIZATION
Regge
FACTORIZATION BREAKING IN SOFT DIFFRACTION
CDF
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 9
Interpret flux as gap formation probability that saturates when it reaches unity
Gap probability (re)normalize to unity
Single diffraction renormalized - 1
yy
yt ,2 independent variables:
t
colorfactor
17.0)0(
)(
ppIP
IPIPIP tg
gap probability sub-energy x-section
KG CORFU-2001: http://arxiv.org/abs/hep-ph/0203141
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 10
yoyt
p eetFCyddt
d
222
)(
Single diffraction renormalized - 2
17.0)0(
)(
ppIP
IPIPIP tg
color
factor
Experimentally: KG&JM, PRD 59 (114017) 1999
QCD:
104.0,02.017.0
pIP
IPIPIPg
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 11
18.03
125.0
8
175.0
121f
1
1f
2
Q
NN cq
cg
Single diffraction renormalized - 3
constsb
sssd
ln
ln~
set to unity determines so
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 12
M2 distribution: dataM2 distribution: data
KG&JM, PRD 59 (1999) 114017
factorization breaks down to ensure M2 scaling!
ε12
2ε
2 )(M
s
dM
dσ
Regge
1
Independent of s over 6 orders of magnitude in M2
M2 scaling
ddM2|t=-0.05 ~ independent of s over 6 orders of magnitude!
data
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 13
Scale s0 and PPP coupling
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 14
Two free parameters: so and gPPP
Obtain product gPPP•so from SD
Renormalized Pomeron flux determines so
Get unique solution for gPPP
Pomeron-proton x-section
os
)(s /2o tgPPP
Pomeron flux: interpret as gap probabilityset to unity: determines gPPP and s0 KG, PLB 358 (1995) 379
)sξ()ξ,t(fdtdξ
σdIP/pIP/p
SD2
Saturation at low Q2 and small x
figure from a talk by Edmond Iancu
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 15
DD at CDF
renormalized
gap probability x-section
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 16
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 17
Rapidity gaps in fireworks!Fermilab1989Opening night at Chez Leon
Rapidity Gaps in Fireworks
SDD at CDF
Excellent agreement between data and MBR (MinBiasRockefeller) MC
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 18
Total, elastic & inelastic cross sections
GeV2
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 19
KG Moriond 2011, arXiv:1105.1916
elp±p =tot×(eltot), with eltot from CMG
small extrapol. from 1.8 to 7 and up to 50 TeV )
CMG
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 20
The total x-section
√sF=22 GeV
98 ± 8 mb at 7 TeV109 ±12 mb at 14 TeV
Main error from s0
Reducing the uncertainty in s0
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 21
glue-ball-like object “superball” mass 1.9 GeV ms
2= 3.7 GeV agrees with RENORM so=3.7
Error in s0 can be reduced by factor ~4 from a fit to these data!
reduces error in t.
TOTEM results vs PYTHIA8-MBR
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 22
inrl7 TeV= 72.9 ±1.5 mb inrl
8 TeV= 74.7 ±1.7 mbTOTEM, G. Latino talk at MPI@LHC, CERN 2012
MBR: 71.1±5 mb
superball ± 1.2 mb
RENORM: 72.3±1.2 mbRENORM: 71.1±1.2 mb
SD and DD cross sections vs predictions
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 23
KG*: from CMS measurements after extrapolation into low using the KG model.
Includes ND background
KG*
KG*
CD/DPE at CDF
Excellent agreement between data and MBR low and high masses are correctly implemented
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 24
Difractive cross sections
1=0.9, 2=0.1, b1=4.6 GeV-2, b2=0.6 GeV-2, s′=s e-y, =0.17, 2(0)=0, s0=1 GeV2, 0=2.82 mb or 7.25 GeV-2
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 25
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 26
Inelastic cross sections at LHC vs predictions
TOTEPYTHIA8+MBR
Monte Carlo Strategy for the LHC …
tot from SUPERBALL model optical theorem Im fel(t=0) dispersion relations Re fel(t=0) el using global fit
inel = tot-el
differential SD from RENORM use nesting of final states forpp collisions at the P -p sub-energy √s' Strategy similar to that of MBR used in CDF based on multiplicities from:
K. Goulianos, Phys. Lett. B 193 (1987) 151 pp“A new statistical description of hardonic and e+e− multiplicity distributios “
T
optical theoremIm fel(t=0)
dispersion relationsRe fel(t=0)
MONTE CARLO STRATEGY
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 27
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 28
Monte Carlo algorithm - nesting
y'c
Profile of a pp inelastic collision
y‘ < y'min
hadronize
y′ > y'min
generate central gap
repeat until y' < y'min
ln s′=y′
evolve every cluster similarly
gap gapno gap
final stateof MC
w/no-gaps
t
gap gap gap
t t t1 t2
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 29
SUMMARY
Introduction
Diffractive cross sections:
basic: SD1,SD2, DD, CD (DPE)
combined: multigap x-sections
ND no diffractive gaps:
this is the only final state to be tuned
Total, elastic, and total inelastic cross sections
Monte Carlo strategy for the LHC – “nesting”
derived from NDand QCD color factors
Thank you for your attention
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 30
Images
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 31
Fermilab 1971First American-Soviet Collaboration
Elastic, diffractive and total cross sections
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 32
At the gorge of Samaria (1980)-I
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 33
At the gorge of Samaria (1980)-II
with R. Feynman – a day of jokes!
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 34
Opening night at Chez Leon
Fermilab1989Opening night at Chez Leon
ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 35
The End
The End!