Single Diffractive Higgs Production at the LHC *

1. SingleDiffractive Higgs Production at the LHC* Mairon Melo Machado melo.machado@ufrgs.br SILAFAE 2010 – VALPARAÍSO, CHILE, 06 – 11 DECEMBER 1 * Work with G. G. Silveira and M. B. Gay Ducati

2. Motivation Diffractive Physics Higgs production at LO Higgs production at NLO Inclusive and diffractive cross section Pomeron Structure Function Multiple Pomeron Scattering Results Conclusions Outlook

3. Motivation • Compute single diffractive and Double Pomeron Exchange (DPE) production of the Standard Model Higgs Boson • Considering diffractive factorization formalism • Parametrization for the Pomeron Structure Function H1 Collaboration (2006) • Cross section computed at NLO accuracy • Gluon fusion process leading mechanism to the Higgs boson production • Gap survival probability rescattering corrections due to spectator particles • Single diffractive ratio computed for proton-proton collisions at the LHC • Estimations for the single and DPE events in the LHC kinematical regime

4. The TEVNPH Working Group, 1007.4587 [hep-ph] Motivation • LHC opens a new kinematical region: • CM Energy in pp Collisions: 14 TeV 7x Tevatron Energy • Luminosity: 10 – 100 fb-1 10 x Tevatron luminosity • Evidences show new allowed mass range excluded for Higgs Boson production • Tevatron exclusion ranges are a combination of the data from CDF and D0

5. Diffractive processes rapidity gap Exchange of a Pomeron with vacuum quantum numbers Pomeron with substructure DPDFs Diffractive distributions of quarks and gluons in the Pomeron Introduction MBGD, M. M. Machado and M. V. T. Machado, PRD What is the Pomeron ? • Diffractive structure function • Gap Survival Probability (GSP) • Cross sections at NLO

6. Diffractive Higgs Production • Single diffraction in hadronic collisions • One of the colliding hadrons emits Pomeron • Partons in the the Pomeron interact with partons from the another hadron Absence of hadronic energy in the final state Rapidity gaps • Double Pomeron Exchange in hadronic collisions • Both colliding hadrons emit Pomeron • Partons in the the Pomerons interact with each other 6

7. D. Graudenz et al. PRL 70 (1993) 1372 Higgs production • Focus on the gluon fusion • Main production mechanism of Higgs boson in high-energy pp collisions • Gluon coupling to the Higgs boson in SM triangular loops of top quarks Lowest order to gg contribution

8. Partonic cross section M. Spira et al. 9504378 [hep-ph] • Lowest order parton cross section expressed by the gluonic width of the Higgs boson Quark Top gg invariant energy squared • dependence

9. LO hadroproduction • Lowest order two-gluon decay width of the Higgs boson PDFs MSTW2008 • Gluon luminosity • Lowest order proton-proton cross section • Renormalization scale • s invariant pp collider energy squared

10. NLO Cross Section • Gluon radiation two parton final states • Invariant energy in the channels • New scaling variable supplementing and • The final result for the pp cross section at NLO • Renormalization scale in αs and the factorization scale of the parton densities to be fixed properly

11. NLO Cross Section • Coefficient contributions from the virtual two-loop corrections • Regularized by the infrared singular part of the cross section for real gluon emission • Infrared part • Finite τQ dependent piece • Logarithmic term depending on the renormalization scale μ

12. Delta functions • Contributions from gluon radiation in gg, gq and qq scattering • Dependence of the parton densities renormalization scale μ factorization scale M • Renormalization scale QCD coupling in the radiative corrections and LO cross sections

13. dfunctions F+ usual + distribution Considering only the heavy-quark limitRegion allowed by Tevatron combination

14. Diffractive cross section Single diffractive Double Pomeron Exchange Gluon distributions in the Pomeron Normalization Gluon distributions in the proton MSTW (2008) H1 parametrization (2006) Gluon distributions (i ) in the Pomeron IP Pomeron flux

15. A. Aktas et al, Eur. J. Phys. J. C48 (2006) 715 H1 parametrization • Range of data 0.0043 < z < 0.8 • In this work, FIT B. • z is the momentum fraction of the Pomeron

16. Gap Survival Probability (GSP) • Absorptive corrections by Multiple Pomeron Scattering • <|S|2> gap survival probability (GSP) Gap • A(s,b) diffractive process amplitude • PS(s,b) probability that no inelastic interactions occurs (remains particles) Comparison between GLM and KKMRmodels at LHC energies KKMR = 6 % GLM = 8 % SD KKMR = 2.6 % GLM = 6 % DPE 16

17. FIT Comparison

18. Higgs production as ρ function (NLO) ρ = μ / MH FIT B MH = 120 GeV

19. Conclusions Inclusive Single Diffractive Double Pomeron Exchange Higgs production atLHC energies NLO • Theoretical predictions • Estimate for cross sections as a function of ρ = μ/MH • Diffractive ratio using hard diffractive factorization and absorptive corrections • LO rate prediction (7 – 9 %) (without GSP)NLO (12% without GSP) • Different predictions to NLO cross sections using two GSP models (KKMR and GLM) • Feasible value of cross sections for both GSP models S. Erhan et al, arxiv/0312342 (2003) SD ~ 250 - 470 fb DPE ~ 28 – 66 fb Very small diffractiveratios to Higgs Mass ~ 120 GeV at NLO without GSP SD ~ 1.0 % MBGD, G. G. Silveira PRD 82 073004 (2010) DPE ~ 0.1 %