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Predictions of Soft Processes at the LHC Implemented in PYTHIA8

Detailed insight into Soft Processes at the Large Hadron Collider using the PYTHIA8 simulation by Konstantin Goulianos, utilizing a unique parton model approach and unitarization procedures. Investigation into diffractive exchange properties and factorization breaking effects.

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Predictions of Soft Processes at the LHC Implemented in PYTHIA8

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  1. Predictions of Soft Processes at the LHC Implemented in PYTHIA8 Konstantin Goulianos* The Rockefeller University * with: Robert Ciesielski 1 Soft Processes at LHC in PYTHIA8 K. Goulianos

  2. CONTENTS • Introduction • Cross Sections • (Event Generation) • (Implementation in PYTHIA8) • (Conclusion) Soft Processes at LHC in PYTHIA8 K. Goulianos

  3. INTRODUCTION • This is an adaptation of the MBR (Minimum Bias Rockefeller) simulation RENORM to PYTHIA8. • successfully tested at Fermilab 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. • Gap Cross Sections: • Gap cross sections vs gap width: • Absolutenormalization! • Hadronization of dissociated proton: • Implemented by introducing a (non-perturbative) “quark string” and tuning it to reproduce the MBR multiplicity and pT distributions. • dN/dh, pT, and particle ID (new in this implementation; the original MBR produced only p± and p0) • Unique unitarization procedure based on a saturated exchange. • Total Cross section: based on a saturated Froissart bound leading to a ln2s dependence. • Immune to eikonaalization models that plague the field! Soft Processes at LHC in PYTHIA8 K. Goulianos

  4. 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 Soft Processes at LHC in PYTHIA8 K. Goulianos

  5. 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 Soft Processes at LHC in PYTHIA8 K. Goulianos

  6. 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 Soft Processes at LHC in PYTHIA8 K. Goulianos

  7. 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 • Question: • does factorization breaking affect t-distributions? Soft Processes at LHC in PYTHIA8 K. Goulianos

  8. DD at CDF gap probability x-section renormalized CDF Diffraction and Exclusive Production

  9. SDD at CDF • Excellent agreement between data and MBR (MinBiasRockefeller) MC CDF Diffraction and Exclusive Production

  10. CD (DPE) at CDF • Excellent agreement between data and MBR  low and high masses are correctly implemented CDF Diffraction and Exclusive Production

  11. Cross Sections el tot CD SD SD DD • SD  single diffraction (single dissociation) • DD  double dissociation (double diffraction) • CD  central dissociation (double pomeron exchange) Soft Processes at LHC in PYTHIA8 K. Goulianos

  12. Total, elastic, and inelastic x-sections GeV2 Soft Processes at LHC in PYTHIA8 K. Goulianos

  13. Total, elastic, and inelastic x-sections versus √s Soft Processes at LHC in PYTHIA8 K. Goulianos

  14. 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 Soft Processes at LHC in PYTHIA8 K. Goulianos

  15. 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). Soft Processes at LHC in PYTHIA8 K. Goulianos

  16. 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). Soft Processes at LHC in PYTHIA8 K. Goulianos

  17. 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 Soft Processes at LHC in PYTHIA8 K. Goulianos

  18. Thank you for your attention Soft Processes at LHC in PYTHIA8 K. Goulianos

  19. References in arXiv:1205.1446v1 [hep-ph] multiplicities Soft Processes at LHC in PYTHIA8 K. Goulianos

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