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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: - PowerPoint PPT Presentation
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Predictions of Diffractive Cross Sections in Proton-Proton Collisions
Konstantin Goulianos*
The Rockefeller University
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 1
CONTENTS
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 2
For details on the phenomenology of the predictions see:
DIFFRACTION 2010“Diffractive and total pp cross 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.
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):
Absolute normalization! Hadronization of dissociated proton:
A (non-perturbative) “quark string” is introduced and tuned to reproduce the MBR multiplicity and pT distributions.
dN/d, pT, and particle ID: new in this PYTHIA8 implementation (the original MBR simulation produced only ± and 0).
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.
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 3
STUDIES OF DIFFRACTION IN QCD
Diffractive
Colorless vacuum exchange
large-gap signature
Non-diffractive
color-exchange gaps exponentially suppressed
POMERON
Goal: probe the QCD nature of the diffractive exchange
rapidity gapIncident hadrons acquire colorand break upart
CONFINEMENT
Incident hadrons retain their quantum numbersremaining colorless
p p p p
p
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 4
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 size
pp
MX
pp’
SINGLE DIFFRACTION
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 5
DIFFRACTION AT CDF
Single Diffraction orSingle Dissociation
Double Diffraction or Double Dissociation
Double Pom. Exchange orCentral 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
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 6
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
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 7
DD at CDF
renormalized
gap probability x-section
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 8
SDD at CDF
Excellent agreement between data and MBR (MinBiasRockefeller) MC
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 9
CD (DPE) at CDF
Excellent agreement between data and MBR low and high masses are correctly implemented
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 10
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 11
Two free parameters: s0 and gPPP
Obtain product gPPP•s0 from SD
Renormalized Pomeron flux
determines s0
Get unique solution for gPPP
Pomeron-proton x-section
)(sσξ)(t,fdtdξ
σdpIPIP/p
SD2
0s
)(s /20 tgPPP
Pom. flux: interpret as gap probabilityset to unity: determines gPPP and s0
KG, PLB 358 (1995) 379
So=3.7±1.5 GeV2
gPPP=0.69 mb-1/2=1.1 GeV -1
Scale s0 and triple-pom coupling
Slide #16Ddffr. 2012
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 12
Reduce the uncertainty in s0
Cross Sections
SD single diffraction (single dissociation) DD double dissociation (double diffraction) CD central dissociation (double pomeron exchange)
tot el
SD SD DD CD
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 13
Total, elastic, and inelastic x-sections
GeV2
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 14
Total, elastic, and inelastic x-sections versus √s
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 15
TOTEM vs PYTHIA8-MBR
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 16
ALICE tot-inel vs PYTHIA8-MBR
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 17
More on cross sections
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 18
136
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
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 19
Difractive x-sections of √s
Supress x-sections at small gaps by a factor S using the error function with yS=2 for SD and DD, and y=y1+y2 =2 for CD (DPE).
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 20
ALICE SD and DD vs PYTHIA8-MBR
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 21
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+ behavior, with =1.104 in MBR vs 1,08 in PYTHIA8(4C).
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 22
CD (DPE) x-sections at 7 TeV versus (a) y=y1+y2 and (b) y1
Both figures are MBR predictions with a y=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
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 23
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): Absolute normalization!
Hadronization of dissociated proton: A (non-perturbative) “quark string” is introduced and tuned to
reproduce the MBR multiplicity and pT distributions. dN/d, pT, and particle ID: new in this PYTHIA8 implementation (the original MBR simulation produced only ± and 0).
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.
Diffraction 2012 Lanzarote Diffractive Cross Sections in pp Collisions K. Goulianos 24
Thank you for your attention