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LECTURE II

LECTURE II. Outline. Colliders LHC Gaps at LHC Higgs production and searches W production and searches Jets production and searches Vector Meson production and searches Where we are. LHC. CMS experiment. Physics at the LHC.

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LECTURE II

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  1. LECTURE II M. B. Gay Ducati - LISHEP2006

  2. Outline • Colliders • LHC • Gaps at LHC • Higgs production and searches • W production and searches • Jets production and searches • Vector Meson production and searches • Where we are M. B. Gay Ducati - LISHEP2006

  3. LHC M. B. Gay Ducati - LISHEP2006

  4. CMS experiment M. B. Gay Ducati - LISHEP2006

  5. Physics at the LHC • Saturated gluon distributions in colliding nuclei, initial state of the system calculable in perturbative QCD • Plasma has higher temperature and lives longer in partonic state • Jets clearly visible and identifiable • Z0 produced in large numbers M. B. Gay Ducati - LISHEP2006

  6. Energies of colliders last decades High-energy data on total, elastic and diffractive cross section p p explored only up to ISR energies RHIC and LHC M. B. Gay Ducati - LISHEP2006

  7. Tevatron Discrepancy between the two Tevatron determinations at 1.8 TeV favors a ln s increase favors the ln2s dep. E710 result CDF result At = 14 TeV, difference between ln s and ln2s fits amounts to about 15 mb M. B. Gay Ducati - LISHEP2006

  8. Rapidity Gaps at LHC Doable at startup luminosity! 1.1033 2.1033` 1032 1033 1034 1 int. 22% 4% M. B. Gay Ducati - LISHEP2006

  9. Higgs production • The standard Model (SM) of Particle Physics has unified the Eletromagnetic interaction and the weak interaction; • Particles acquire mass through their interaction with the Higgs Field; • Existence of a new particle: the Higgs boson (H). The theory does not predict the mass of H; • Predicts its production rate and decay modes for each possible mass; • CMS optimized to discover the Higgs M. B. Gay Ducati - LISHEP2006

  10. Higgs possible events 800 GeV) 100 GeV 130 GeV 150 GeV M. B. Gay Ducati - LISHEP2006

  11. Higgs bosons • Observe the SM higgs in CMS; • Probe the entire mass range up to MH = 1 TeV; • Extensions of the SM involve a richer set of Higgs bosons; • Minimal Supersymmetric (h0, H0, A0, H+, H-); • Discovery involves the use of more elaborated signatures M. B. Gay Ducati - LISHEP2006

  12. Diffractive Higgs production -jet gap gap H h p p -jet • Exclusive diffractive Higgs production pp p H p : 3-10 fb • Inclusive diffractive Higgs production p p  p + X + H + Y + p :50-200 fb  Jz=0 suppression of g g b b background  Mass measurement missing mass M. B. Gay Ducati - LISHEP2006

  13. Diffractive Higgs Production • The reaction • Protons lose very small fraction of their energy • Nevertheless enough to produce the Higgs Boson Durham Model Here GFis the Fermi constant and Neglected the exchanged transverse momentum in the integrand M. B. Gay Ducati - LISHEP2006

  14. Higgs Studies • SM Higgs: (30fb-1) 11 signal events (after cuts)O(10) background events • Cross section factor ~ 10-20 larger in MSSM (high tan) 100 fb Study correlations between the outgoing protons to analyse the spin-parity structure of the produced boson 1fb A way to get information on the spin of the Higgs Good for LHC 120 140 M. B. Gay Ducati - LISHEP2006

  15. Light Higgs search Numbers for 30 fb-1 Higgs of 120 GeV light Higgs big challenge for LHC M. B. Gay Ducati - LISHEP2006

  16. Higgs searches M. B. Gay Ducati - LISHEP2006

  17. Higgs searches Measure precisely Higgs to bb and WW(*) couplings M. B. Gay Ducati - LISHEP2006

  18. W boson • The reaction was experimentally studied • Production is tagged by a high pT lepton from W decay • Two kinds: W+ and W- Tevatron (2004) M. B. Gay Ducati - LISHEP2006

  19. Diffractive W Production • The cross section for the inclusive lepton production is where , , and The corresponding cross section for W- is obtained by using the lower signs and , where M. B. Gay Ducati - LISHEP2006

  20. W cross sections estimates LHC W/Z cross sections for decay via the lepton mode, for various PDFs M. B. Gay Ducati - LISHEP2006

  21. W rapidity distributions Not HERA data ZEUS-S global PDF analysis HERA data M. B. Gay Ducati - LISHEP2006

  22. W rapidity distributions Not HERA data ZEUS-S PDFs CTEQ6.1PDFs MRTS01 PDFs LHC W+ rapidity distributions and their PDF uncertainies M. B. Gay Ducati - LISHEP2006

  23. W rapidity spectra W- W+ W+ W- Events generated with HERWIG compared to events generated by MC@NLO and fractional differences of these spectra Events generated with MRST02 PDFs reweighted to CTEQ6.1 PDFs compared to events generated directly with CTEQ6.1 PDFs and fractional difference between these spectra. M. B. Gay Ducati - LISHEP2006

  24. Diffractive jets production • Hadroproduction of dijets The cross section for the process in terms of the rapidity η where , ETmin, xIPmin and xIPmax established by exps. cuts , a, b, c, d = partons and M. B. Gay Ducati - LISHEP2006

  25. Diffractive jets production • Photoproduction of dijets • Processes take place by two mechanisms (experimental evidence) whose calculation is considered in terms of (1) the direct component (coupling of the photon to partons of the proton is pointlike) (2) the resolved component (photon fluctuates to a partonic structure whose constitu- ents interact with the partons of the proton). • The partonic structure of the Pomeron is probed by the photon (direct process) or is envolved in interactions with photon constituents (resolved process) M. B. Gay Ducati - LISHEP2006

  26. Diffractive jets production Photoproduction • Cross section for the resolved component and with The integration limits established likewise (limits for the variable y are given in the experiment). • Cross section for the direct component Is the same, only replacing the photon structure function by • Diffractive production data are also given in terms of other cross sections dσ/dET, dσ/dW, dσ/dβ, ... M. B. Gay Ducati - LISHEP2006

  27. Jets Rapidity distributions of jets from diffractive photoproduction processes. The labels indicate the respective Pomeron structure function and flux factor used in calculation. Data by the ZEUS Collaboration (1999) M. B. Gay Ducati - LISHEP2006

  28. Jets Cross sections relative to diffractive photoproduction of jets in comparison to ZEUS data (99). M. B. Gay Ducati - LISHEP2006

  29. Vector meson Basic process Scattering amplitude where and M. B. Gay Ducati - LISHEP2006

  30. Vector meson cross section ρ photo-production Meson ρ See MBGD & W. Sauter 2006 M. B. Gay Ducati - LISHEP2006

  31. M. B. Gay Ducati - LISHEP2006

  32. Where we are IP approach sucesses and failures Perturbative + non-perturbative QCD How exactly? Gaps between jets Gluon ladder exchange A la BFKL UA8 (1988) Experimental evidences HERA TEVATRON LEP Experimental evidences NEXT Overall theoretical understanding LHC Diffractive Higgs production W’s, Z’s, V’s SUSY evidences M. B. Gay Ducati - LISHEP2006

  33. Suggested references Books and review papers • Barone, V. & Predazzi, E. - High-Energy Particle Diffraction, Springer Press 2001 • Forshaw, J. & Ross, D. A. – Quantum Chromodynamics and the Pomeron, Cambridge University Press 1997 • Donnachie, S. Dosch, G., Nachtmam, O. and Landshoff, P. – Pomeron Physics and QCD, Cambridge Univesity Press 2001 • Collins, P. D. B. - An Introduction to Regge Theory and High Energy Physics, Cambridge university Press 2001 • Forshaw, J. – Diffractive Higgs production: theory, arXiv:hep-ph/0508274 v1 2005 • Bjorken, J. D. - Rapidity gaps and jets as a new physics signature in very high energy hadron-hadron collisions, SLAC-PUB-5616 1992 M. B. Gay Ducati - LISHEP2006

  34. Suggested references Books and review papers • Cooper-Sakar, A. M. – Low-x physics and W and Z production at the LHC, arXiv:hep-ph/0512228 v1 2005 • Peschanski, R. – Remarks on diffractive production of the Higgs Boson, arXiv:hep-ph/0511095 v1 2005 • Covolan, R. J. M. & Soares, M. S. – Analysis of the diffractive production of W’s and dijets at the DESY HERA and Fermilab Tevatron Colliders, Phys. Rev. D, Vol 60, 054005, 1999 • Favart, L. - Inclusive diffraction,arXiv:hep-ex/0602001 v1 2006 • Arneodo, M. – Diffraction for non-believers, arXiv:hep-ph/0511047 v1 2005 • Goulianos, K. – Twenty years of diffraction at the Tevatron, arXiv:hep-ph/0510035 v1 2005 M. B. Gay Ducati - LISHEP2006

  35. Suggested references Talks • De Roeck, A. - Diffractive and Forward Physics at the LHC, 10 International Conference Baryons, 2004 • Kopeliovich, B. – Diffraction in QCD, I LAWHEP 2005 • Kagawa, S. - Studies of the Structure of Diffraction and the Diffractive Final State in ep Collision, LLWI 2005 • Capua, M. – Inclusive Diffraction at ZEUS, Low-x International Workshop, 2005 • Ingelman, G – Hard Diffraction – 20 years later, XXII International Symposium on Lepton-Photon Interactions at High Energy, 2005 M. B. Gay Ducati - LISHEP2006

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