Predictions of diffractive cross sections in proton proton collisions
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Predictions of Diffractive Cross Sections in Proton-Proton Collisions. Konstantin Goulianos* The Rockefeller University. CONTENTS. Introduction Cross Sections (Event Generation) (Implementation in PYTHIA8) Conclusions. For details on the phenomenology of the predictions see:

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Predictions of Diffractive Cross Sections in Proton-Proton Collisions

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Predictions of diffractive cross sections in proton proton collisions

Predictions of Diffractive Cross Sections in Proton-Proton Collisions

Konstantin Goulianos*

The Rockefeller University

Diffractive Cross Sections in pp Collisions K. Goulianos


Contents

CONTENTS

  • Introduction

  • Cross Sections

  • (Event Generation)

  • (Implementation in PYTHIA8)

  • Conclusions

For details on the phenomenology of the predictions see:

DIFFRACTION 2010

“Diffractive and total ppcross sections at the LHC and beyond” (KG)

http://link.aip.org/link/doi/10.1063/1.3601406

This talk: an implementation of these cross sections in PYTHIA8.

Diffractive Cross Sections in pp Collisions K. Goulianos


Introduction

INTRODUCTION

  • The RENORM (renormalization model) soft pp cross sections previously used in MBR (Minimum Bias Rockefeller) simulation are adapted to PYTHIA8.

    • MBR was successful at Fermilab in fixed target and collider experiments.

  • RENORM predictions are based on a parton-model approach in which diffraction is derived from inclusive PDFs and color factors.

  • Diffractive cross sections and final states are both predicted:

    • Cross sections vs gap width or vs forward momentum loss of proton(s):

      • Absolutenormalization!

    • Hadronization of dissociated proton:

      • A (non-perturbative) “quark string” is introduced and tuned to reproduce the MBR multiplicity and pT distributions.

      • dN/dh, pT, and particle ID: new in this PYTHIA8 implementation

      • (the original MBR simulation produced only p± and p0).

    • Unique unitarization based on a saturated “glue-ball” exchange.

  • Total Cross section ~ln2s based on a glue-ball-like saturated-exchange.

    • Immune to eikonaalization-model dependences.

Diffractive Cross Sections in pp Collisions K. Goulianos


Studies of diffraction in qcd

p

Incident hadrons acquire color

and break upart

POMERON

CONFINEMENT

STUDIES OF DIFFRACTION IN QCD

  • Non-diffractive

  • color-exchange  gaps exponentially suppressed

  • Diffractive

  • Colorless vacuum exchange

  •  large-gap signature

rapidity gap

Incident hadrons retain their quantum numbers

remaining colorless

p

p

p

p

Goal: probe the QCD nature of the diffractive exchange

Diffractive Cross Sections in pp Collisions K. Goulianos


Definitions

MX

p’

p’

DEFINITIONS

SINGLE DIFFRACTION

x,t

xp

p

p

MX

dN/dh

Rap-gap

Dh=-lnx

0

ln Mx2

ln s

ln s

since no radiation no price paid for increasingdiffractive gap size

Diffractive Cross Sections in pp Collisions K. Goulianos


Diffraction at cdf

SDD

DIFFRACTION AT CDF

sT=Im fel (t=0)

Elastic scattering

Total cross section

OPTICAL

THEOREM

gap

f

f

h

h

DD

SD

DPE /CD

Single Diffraction or

Single Dissociation

Double Diffraction or Double Dissociation

Double Pom. Exchange or

Central Dissociation

Single + Double

Diffraction (SDD)

exclusive

JJ…ee…mm...gg

p

p

JJ, b, J/y,W

Diffractive Cross Sections in pp Collisions K. Goulianos


Factorization breaking in soft diffraction

p’

p

x,t

p

M

540 GeV

1800 GeV

see KG, PLB 358, 379 (1995)

FACTORIZATION BREAKING IN SOFT DIFFRACTION

diffractive x-section suppressed relative to Regge prediction as √s increases

Regge

Factor of ~8 (~5)

suppression at

√s = 1800 (540) GeV

RENORMALIZATION

CDF

√s=22 GeV

Diffractive Cross Sections in pp Collisions K. Goulianos


Dd at cdf

DD at CDF

gap probability

x-section

renormalized

Diffractive Cross Sections in pp Collisions K. Goulianos


Sdd at cdf

SDD at CDF

  • Excellent agreement between data and MBR (MinBiasRockefeller) MC

Diffractive Cross Sections in pp Collisions K. Goulianos


Cd dpe at cdf

CD (DPE) at CDF

  • Excellent agreement between data and MBR

     low and high masses are correctly implemented

Diffractive Cross Sections in pp Collisions K. Goulianos


Scale s 0 and triple pom coupling

Scale s0 and triple-pom coupling

Pom. flux: interpret as gap probability

set to unity: determines gPPP and s0

Slide #16

Ddffr. 2012

KG, PLB 358 (1995) 379

Pomeron-proton x-section

  • Two free parameters: s0 and gPPP

  • Obtain product gPPP•s0e / 2 from sSD

  • Renormalized Pomeron flux determines s0

  • Get unique solution for gPPP

gPPP=0.69 mb-1/2=1.1 GeV -1

So=3.7±1.5 GeV2

Diffractive Cross Sections in pp Collisions K. Goulianos


Reduce the uncertainty in s 0

Reduce the uncertainty in s0

Diffractive Cross Sections in pp Collisions K. Goulianos


Cross sections

Cross Sections

el

tot

CD

SD

SD

DD

  • SD  single diffraction (single dissociation)

  • DD  double dissociation (double diffraction)

  • CD  central dissociation (double pomeron exchange)

Diffractive Cross Sections in pp Collisions K. Goulianos


Total elastic and inelastic x sections

Total, elastic, and inelastic x-sections

GeV2

Diffractive Cross Sections in pp Collisions K. Goulianos


Total elastic and inelastic x sections versus s

Total, elastic, and inelastic x-sections versus √s

Diffractive Cross Sections in pp Collisions K. Goulianos


Totem vs pythia8 mbr

TOTEM vs PYTHIA8-MBR

Diffractive Cross Sections in pp Collisions K. Goulianos


Alice tot inel vs pythia8 mbr

ALICE tot-inel vs PYTHIA8-MBR

Diffractive Cross Sections in pp Collisions K. Goulianos


More on cross sections

More on cross sections

136

Diffractive Cross Sections in pp Collisions K. Goulianos


Difractive x sections

Difractive x-sections

a1=0.9, a2=0.1, b1=4.6 GeV-2, b2=0.6 GeV-2, s′=s e-Dy, k=0.17, kb2(0)=s0, s0=1 GeV2, s0=2.82 mb or 7.25 GeV-2

Diffractive Cross Sections in pp Collisions K. Goulianos


Difractive x sections of s

Difractive x-sections of √s

  • Supress x-sections at small gaps by a factor S using the error function with DyS=2 for SD and DD, and Dy=Dy1+Dy2 =2 for CD (DPE).

Diffractive Cross Sections in pp Collisions K. Goulianos


Alice sd and dd vs pythia8 mbr

ALICE SD and DD vs PYTHIA8-MBR

Diffractive Cross Sections in pp Collisions K. Goulianos


Sd and dd at 7 tev mbr vs pythia8 4c

SD and DD at 7 TeV MBR vs PYTHIA8-4C

  • The differences between the PYTHIA8(4C) and MBR predictions are mainly due to the (1/M2)1+e behavior, with e=1.104 in MBR vs 1,08 in PYTHIA8(4C).

Diffractive Cross Sections in pp Collisions K. Goulianos


Cd dpe x sections at 7 tev versus a d y d y 1 d y 2 and b d y 1

CD (DPE) x-sections at 7 TeV versus (a) Dy=Dy1+Dy2 and (b) Dy1

  • Both figures are MBR predictions with a Dy=2 cut-off in the error function.

  • The normalization is absolute with no model uncertainty other than that due to the determination of the parameters in the formulas as determined from data

Diffractive Cross Sections in pp Collisions K. Goulianos


Summary introduction

SUMMARY  introduction

  • The ENORM (renormalization model) soft pp cross sections previously used in MBR (Minimum Bias Rockefeller) simulation are adapted to PYTHIA8.

    • MBR was successful at Fermilab in fixed target and collider experiments.

  • RENORM predictions are based on a parton-model approach, in which diffraction is derived from inclusive PDFs and color factors.

  • Diffractive cross sections and final states are both predicted:

    • Cross sections vs gap width or vs forward-momentum loss of proton(s):

      • Absolutenormalization!

    • Hadronization of dissociated proton:

      • A (non-perturbative) “quark string” is introduced and tuned to reproduce the MBR multiplicity and pT distributions.

      • dN/dh, pT, and particle ID: new in this PYTHIA8 implementation

      • (the original MBR simulation produced only p± and p0).

    • Unique unitarization based on a saturated “glue-ball” exchange.

  • Total Cross section ~ln2s based on a glue-ball-like saturated-exchange.

    • Immune to eikonaalization-model dependences.

Thank you for your attention

Diffractive Cross Sections in pp Collisions K. Goulianos


References in arxiv 1205 1446v2 hep ph

References in arXiv:1205.1446v2 [hep-ph]

multiplicities

Diffractive Cross Sections in pp Collisions K. Goulianos


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