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Predictions of Diffractive, Elastic, Total, and Total-Inelastic pp Cross Sections vs LHC Measurements
Konstantin Goulianos The Rockefeller University
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 1
http://dis2013.in2p3.fr/
http://physics.rockefeller.edu/dino/my.html
CONTENTS
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 2
The total pp cross section at LHC is predicted in a special fully unitarized parton model which does not employ eikonalization and does not depend on knowledge of the -value.
The following diffractive cross sections are described in this model based on a LO QCD approach: SD – SD1/SD2, single dissociation (one/the other proton dissociates). DD - double dissociation (both protons dissociate). CD – central dissociation (neither proton dissociates, but there is
central production of particle). This approach allows a unique determination of the Regge triple Pomeron
coupling (PPP). Details can be found in ICHEP 2012, 6 July 2012, arXiv:1205.1446 (talk by
Robert Ciesielski and KG).
DIFFRACTION IN QCD
Diffractive events
Colorless vacuum exchange
-gaps not exp’ly 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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 3
DEFINITIONS
MX
dN/d
,t
p’rap-gap=-ln
0s
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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements 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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements 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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements 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?
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements 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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 8
* similarly for (del/dt)t=0 w.r.t. tbut this is handled differently in RENORM
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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements 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 subenergy x-section
KG CORFU-2001: http://arxiv.org/abs/hep-ph/0203141
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements 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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements 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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements 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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 13
Scale s0 and PPP coupling
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements 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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 15
DD at CDF
renormalized
gap probability x-section
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 16
SDD at CDF
Excellent agreement between data and MBR (MinBiasRockefeller) MC
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 17
CD/DPE at CDF
Excellent agreement between data and MBR low and high masses are correctly implemented
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 18
Difractive x-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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 19
Total, elastic, and inelastic x-sections
GeV2
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 20
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
The total x-section
√sF=22 GeV
98 ± 8 mb at 7 TeV109 ±12 mb at 14 TeV
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 21
Main error from s0
Reduce the uncertainty in s0
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 22
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 vs PYTHIA8-MBR
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 23
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
CMS SD and DD x-sections vs ALICE: measurements and theory models
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 24
KG*: after extrapolation into low from measured CMS data using the MBR model:find details on data in Robert Ciesielski’s talk on Wed. at 15:30.
Includes ND background
KG*KG*
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 25
Total-Inelastic Cross Sections vs model predictions
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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 26
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 27
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
DIS-2013, Marseille Diffractive X-Sections vs LHC Measurements K. Goulianos 28
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