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

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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

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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

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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

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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

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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

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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

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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

CD/DPE at CDF

Excellent agreement between data and MBR low and high masses are correctly implemented

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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

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Total, elastic & inelastic cross sections

GeV2

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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

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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

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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

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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 25

KG*: from CMS measurements after extrapolation into low using the MBR model

Includes ND background

KG*

KG*

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Inelastic cross sections at LHC vs predictions

TOTEMPYTHIA8+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

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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

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At the gorge of Samaria (1980)

ICNFP-2013, Kolymbari Predictions of Diffraction at the LHC K. Goulianos 33

Opening night at Chez Leon

Fermilab1989Opening night at Chez Leon

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The End

The End!