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 Selected Highlights of the First Workshop  Goals for the 2 nd Workshop

HERA and the LHC 2 nd workshop on the implication of HERA for LHC physics.  Selected Highlights of the First Workshop  Goals for the 2 nd Workshop. A De Roeck (CERN) Lisbon 29/06/06. Examples: HERA  LHC. Underlying event: tunable elementarity of one beam particle

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 Selected Highlights of the First Workshop  Goals for the 2 nd Workshop

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  1. HERA and the LHC2nd workshop on the implication of HERA for LHC physics  Selected Highlights of the First Workshop  Goals for the 2nd Workshop A De Roeck (CERN) Lisbon 29/06/06

  2. Examples: HERA LHC Underlying event: tunable elementarity of one beam particle p *p collisions LHC: event complexity B-production: B quark PDFs of the proton LHC: Higgs production Structure functions and parton distributions LHC: cross sections/precision Diffraction LHC: diffractive scalar production

  3. Workshop Aims http://www.desy.de/~heralhc Workshop Chairs H. Jung, ADR  Five Working Groups  Parton density functions  Multi-jet final states  Heavy quarks (charm and beauty)  Diffraction  MC-tools 6 major meetings in 12 months

  4. Proceedings • Phase I of this workshop concluded with the proceedings • However an important link between communities has been established. • March 05’: We should not just let it fade away, but strongly exploit it, to the benefit of both communities. • Therefore keep momentum with one HERA/LHC meeting per year • Keep also good contacts with TeV4LHC workshop activities (started Sept.2004) Many thanks to all conveners and authors ! 2006 CERN: 6-9 June 2007 DESY March or May/June 07 2008 CERN (first LHC physics? ) hep-ph/0601012 hep-ph/0601013 Available on request from CERN/DESY libs >650 pages June Workshop: 17 plenary talks 80 parallel talks

  5. PDFs & ADD extra dimensions: di-jet final state Graviton exchange contributions reduce the cross section (interference) S. Ferrag Reduction of the sensitivity due to PDF uncertainty (CTEQ6)

  6. Impact of Future HERA Data  Improvement in PDF precision with projected 700 fb-1 of data in HERA-II  Includes jets in DIS and p  Note only HERA (ZEUS) data are used in the fits Gwenlan Cooper-Sarkar Targett-Adams hep-ph/0509220

  7. Average HERA data From M. Cooper-Sakar, C. Gwenlan and S. Glazov • Combined PDF fit to H1& ZEUS • Average H1&ZEUS data sets Much reduced uncertainties .... Model independent analysis of data desirable get THE HERA – PDF !!!!!

  8. LHC Kinematics/QCD evolution Evolution of PDFs to high Q2 & low x important at the LHC Precision? Level of approximation? CCFM/BFKL?, non-linear effects?

  9. Impact of the measurement of FL R. Thorne H. Stenzel FL could referee the gluon distribution! FL is like F2: little theoretical ambiguity (compared to e.g. F2C) Need to lower the energy of proton or electron beam for this measurement See J. Feltesse

  10. Measuring FL Detailed study for H1, with 2 lower proton beam energy settings Feltesse/Klein et al FL can referee between MRST and CTEQ gluons FL is gluon driven CTEQ MRST FL measurement in 2007 !

  11. PDF Group plans (summary) • A good preparation for the LHC start needs also to include: • realistic simulations to optimize data analysis and data interpretations • need to investigate and identify final states where accurate x-section measurements/calculations can be made • Find a realistic interactive (HERA-LHC) strategy to constrain PDF's • Experimentalists and theorists have to “learn” how to measure and calculate the same things ! • Should form a “group” from ATLAS, CMS, LHCb, ALICE, H1, ZEUS and theoretical PDF experts M. Dittmar

  12. PDF determination at LHC • ~ 105 c+b events in 10 fb-1 with ptmuon >10 GeV • xc,xb probed in 0.05<xc,xb<0.1 with 10% stat.accuracy • xs ~0.1 for 10 fb-1 with 10% stat. accuracy • need u,d uncertainties • simulation of final state including frag.fct and PS K. Mazumdar et al charm quark PDF See also talk on M. Cooper strange quark PDF

  13. Underlying event/multiple interactions What is the underlying event (UE), multiple parton interactions (MI)? • Everything, except the LO process we're currently interested in • parton showers • additional remnant – remnant interactions • Do Tevatron tunes work at HERA? from R. Field

  14. Effect of underlying event on central jet veto in VBF Higgs Uncertainty of the central jet veto efficiency due to UE model; ATLAS. H->WW*->2l in qqH prod. Rapidity of the central jet in Higgs events; CMS; full simulation, L=2x1033cm-2s-1 Pythia 6.214 ATLFAST 602 “bkg. like” behaviour for soft jets; fake jets: pile up+UE+detector

  15. Initial kT at HERA and LHC Jung Cascade calculation Initial kT in the hard scattering Higgs <kT> large  unintegrated parton PDFs will be needed Test predictions at HERA Large kT effects affect Higgs searches Measure unintegrated PDFs f(x,Q2,kT2) at HERA via final states

  16. Non-linear effects at LHC A. Dainese et al Nonlinearevolution equation for uPDF: (Balitsky-Kovchegovequation) estimates for ALICE × Bottom suppression due to non-linear effects in BK • Significant effects... • up to factor of 2 in hot spot scenario • factorization still ok ?

  17. HERA II analysis (expect factor 10 more), larger kinematic range • Understand b-production mechanism (...remember b-puzzle at the TeVatron...) • NOTE: gluon drives heavy quark PDFs .... transverse momenta ???? HERA: Heavy Quark PDFs at large Q2 Current H1 (HERA I) analysis From O.Behnke, A. Geiser, A. Meyer, M. Wing beauty charm

  18. Uncertainties in HQ production • Leading uncertainties are: • scales & fragmentation Can these uncertainties be reduced ? • pert. corr. known to NLO. NNLO is hard, but feasible (work started...) • fragmentation is presently refined at NLL level A. Mitov charm at LHC b at LHC Important also for top mass measure: B-meson and lepton

  19. Exclusive Higgs Production Exclusive diffractive Higgs production pp p +H+ p : 2-10 fb Cross section ‘stabelized’ during the previous workshop -jet E.g. V. Khoze et al M. Boonekamp et al. B. Cox et al. … gap gap H h p p Advantages Exclusive:  Jz=0 suppression of ggbb background  Mass measurement via missing mass -jet beam dipole dipole M = O(1.0 - 2.0) GeV p’ Experimental effort started See B. Cox p’ roman pots roman pots

  20. Ideas for upgrading forward region • Idea to fill gap in rapidity with calorimeter at 135 m in front of TAN ( E ~ 2.0 - 5.5 TeV and pseudorapidity range 8 – 12 ) • Beamline simulation performed • Pseudorapidity resolution ~ 0.25-0.5 ( depends on the selected energy rapidity range) • Radiation level near the calorimeter at 135 m is reasonable (from studies of ZDC) • Tracker in front of calorimeter to improve coordinate resolution (GEM) V.Andreev, A.Bunyatyan, K.Borras, HJU, M.Kapishin, L.Lytkin

  21. MC and other Tools • Parton distribution library: • LHAPDF now official carrier of the PDFs • Used by LHC experiments in generators • HERA pdfs have been added • Allows error uncertainty estimates • Pion and photon added, particularly for HERA. F2D next? • NLOLIB framework for NLO QCD programs • Uniform user interface/interface to HZTOOL • e+e-/ep included, pp can be added • HZTOOL/JetWeb/RunMC/Cedar(?) for tunning • All HERA results to be included, some e+e-. Include more pp? • RAPGAP, Cascade Monte Carlos for inclusive and diffractive pp • Plenty of exchange on other MC tools, leading to new MC tools and comparisons with ep where possible • Continuation of the MC@LHC 2003 workshop , concerning validation A new MC@LHC workshop this summer 2006: July 17-26

  22. Nutshell: Results from HERA/LHC I • Parton Distribution Functions • Dialogue/discussion between PDF fitters and community that delivers the data. • Combined data (H1/Zeus Datasets for F2, F2D), other data (e.g. TeV. jets)? • Discrepancies between PDFs will be ironed out, eg via to new measurements. Fits with 1- bands available. • Quantitative estimates for low-x/large-x resummation available • Timescale for the full program 1-2 years, i.e. just in time for the LHC  Will lead to more precise PDFs: maybe factor 2? (personal guess/hope) • Diffraction • Improved understanding on the DPE/Higgs production and cross section • Final states • Lots of work/progress on underlying events (tuning), gap survival • Heavy quarks • Saturation effects measurable at low pt • Heavy quark parton distributions eg. for Higgs cross section calculations. • Tools • Tool developments ongoing strongly…

  23. Keywords: tools, phenomenological progress, and quantitative estimate for the impact of HERA on LHC measurements What LHC needs for start in 2007 ? • PDF determination: • Best possible PDF • Uncertainties on the PDF and evolution • Special PDFs? Diffractive, unintegrated, generalized.. • Event topologies: • Multiple Interactions • Underlying Events • Higher Order Corrections • Reliable Simulations/ Theory/Models • tuning of free parameters to many different measurements • improved calculations • alternative approaches Goals for HERA/LHC II

  24. Multijets & final states Underlying events, un-integrated pdfs L. Lonnblad, G. Zanderighi, C. Gwenlan, N. Tuning, S. Banerjee, Ch. Risler, D. Traynor Structure functions and parton distributions S. Forte, S. Moch, M. Dittmar, A. Glazov M. Botje MC - Tools S. Gieseke, F. Krauss, T. Kluge, P. Bartalini, P. Robbe, S. Chekanov Diffraction M. Diehl, V. Khoze M. Arneodo, P. Newman, A. Bruni, B. Cox, R. Orava Working Groups of the workshop Heavy quarks: B quark pdfs of the proton, fragmentation fct, u-pdfs M. Cacciari,H. Spiesberger, A. Dainese, A. Geiser, K. Lipka,U. Uwer

  25. Backup

  26. non-linear (quadratic) correction has “–” sign • Q2 evolution is slower • refit HERA F2 data, reduces F2DGLAP at low x and moderate Q2 • xg(x,Q2) at low Q2 (<10 GeV2) and x (<10-3) is larger than in DGLAP Deviations: non-linear effects in QCD evolution? A. Dainese et al GribovLevinRyskin-MuellerQiuequation: estimates for ALICE • Get these non-linear effects better understood from HERA ! • Precise HERA data important !!! • connection to MI, diffraction ...

  27. HERA: QCD structure of the proton LHC: Higgs, SUSY etc, but mostly QCD... Why HERA and the LHC? electron proton collider HERA √s = 320 GeV proton proton collider LHC √s = 14 TeV typical range

  28. Supersymmetry? Extra Dimensions? Precision determination of PDFs needed ... understanding QCD is the key to new physics Precise PDFs for the LHC inclusive jet xsection D.Stump et al hep-ph/0303013 Signature for new physics • jet x-section Discovery potential depends on precise PDFs CTEQ6 uncertainties CTEQ6.1

  29. Low lumi Rapidity gap selection possible HF, Castor, BSCs, T1, T2 Proton tag selection optional RPs at 220m and 420 m Diffraction is about 1/4 of tot High cross section processes “Soft” diffraction Interesting for start-up running Important for understanding pile-up High lumi No Rapidity gap selection possible Proton tag selection indispensable RPs at 220m and 420 m Central exclusive production Discovery physics: Light SM Higgs MSSM Higgs Extra dimensions Gamma-gamma and gamma-proton interactions (QED) Forward energy flow - input to cosmics shower simulation QCD: Diffraction in presence of hard scale Low-x structure of the proton High-density regime (Color glass condensate) Diff PDFs and generalized PDFs Diffractive Drell-Yan CMS + Totem + FP420 M. Grothe Low lumi High lumi Monika Grothe, CMS diffractive and forward physics program, June 2006

  30. Detector stations at 220 m and 420 m from Interaction point 420 m station is in cold region.... – Hamburg pipe B. Cox, M Grothe, H. Kowalski et al. Measurement of exclusive Higgs • goal: mass resolution 1 GeV for Higgs with • 420 m stations are needed for low mass Higgs • other issues: triggers gap-survival rates 220 m 420 m

  31. Parton Density Functions and all that • collinear PDFs • uPDFs (single and double unintegrated) • diffractive and generalised PDFs Exclusive Higgs production

  32. Topics Parton Density Functions and all that... (assuming we have the proper theory) Event Topologies and all that ... (going beyond the well known ... )

  33. Monte Carlo and Tools • Include also LEP data • Provide tuning including HERA, LEP and TeVatron data !!! C. Risler, J Butterworth HZtool • calculate and compare predictions with measurements • MC generators, NLOlib, MC@NLO • useful for tuning of parameters • useful for PDF fits with final states • includes HERA, LEP, TeVatron data • will be coupled to HEPDATA • will develop into RIVET (Robust Independent Validation of Experiment and Theory) a C++ version of HZTool. Work started ! • MC/NLO validation • compare to very different measurements • Request by HERA & TeVatron & LHC: • include all available infos for benchmarking, validation and tuning example for tuning: ARIADNE parameters with new PDFs compare to fwd jet xsection (not used in tuning)(A. Knutsson, L. Joensson)

  34. CMS IP T1/T2, Castor, BSC ZDC RPs@150m RPs@220m possibly detectors@420m TOTEM FP420 xL=P’/Pbeam=  Nominal LHC beam optics, * =0.5m: TOTEM: 0.02 <  < 0.2 FP420: 0.002 <  < 0.02 FP420 M. Grothe FP220 and FP420 program also in ATLAS !!!

  35. Exclusve Higgs production, again... • Numerous papers by V. Khoze, A. Martin, M. Ryskin, A. Kaidalov, J. Stirling: L. Motyka New investigation of rescattering effects by L. Motyka, J. Bartels, S. Bondarenko, K. Kutak L. Motyka: • First correction due to hard rescattering are large, and negative • need to perform resummation • Durham assumption of factorization of hard production and soft rescattering does not hold, unless special cancellations occur • Needs further clarification

  36. Goals and suggestions for 2nd workshop H. Jung/ADR • precision determination of PDFs, including uPDFS and generalised PDFs • what precision can be expected in 2007/2008 from the HERA and perhaps combined with other data and with the improvements in theory? This was started in the first workshop but is it the final word for LHC preparation • how does it affect LHC measurments quantitatively • combined H1/ZEUS parton data sets (started at the previous) • can we judge which PDF is preferred (MRST/CTEQ...) in 2007/2008 eg.from FL or LHC measurements? • MI/underlying events/jets • uncertainties for top/Higgs production • underlying event tuning at HERA (as for the Tevatron data) • testing new underlying event models with data • new advised parameter set for underlying events • Quantative uPDFs and MI influence for SUSYHiggs discoveries • Understanding MI interactions with HERA data (AGK,…) • uncertainties for gap-survival probabilities for the LHC • Test HO/resummed jet predictions at HERA

  37. Goals and suggestions for 2nd workshop • Heavy Quarks: details of production mechanisms • beauty at HERA -> top at LHC ? • higher orders • small x/ large x resummations • saturation effects • Include HERA charm data for gluon constraints in fits (like the jets) • diffraction and small x • saturation and non-linear effcts: • what is the saturation scale, where HERA can help • is saturation relevant for LHC, and where ? • physics of the forward region • elastic protons • jets in 6 < eta < 11 • what can be learned from total xsection sigma_tot for ptcut in multiple scatterings ? • How to relate diffraction with multiple scatterings • continuing studies on the exclusive Higgs production and detection

  38. Goals and suggestions for 2nd workshop MC & Tools - HZTool -> relevanca also for MC@NLO - benchmarking of xsections for HERA and LHC: jets, W/Z, Higgs, HQ, diffraction - Tools for pdf fits including proper treatment of alphas, different evolution (DGLAP LO/NLO/NNLO, CCFM/BFKL) proper treatment of data uncertainties extraction of PDFs, uPDFs, generalised PDFs - NLO programs and libraries - SCET type of QCD generators for multi-jet production? Keywords: tools, phenomenological progress, and quantitative estimate for the impact of HERA on LHC measurements

  39. j1 W j2 t b-jet Physics at the LHC: pp @ 14 TeV Extra Dimensions? Higgs! CP triangle! Supersymmetry? QGP? Precision measurements e.g top! Split SUSY? But also QCD, diffraction, b & c physics,… especially in the early phase These need to be understood for precision measurements, bkg understanding etc Important role for HERA data & HERA expertise  This workshop

  40. Physics at the LHC: other examples High energy hadron showers Multi Jet event: Is it Multiple Interaction or Black hole production Color glass Condensate UHE CR LHC QCD @ LHC in its own!!! High scale QCD, jets, UHECR, smallest x, parton saturation - new phase in QCD - non-linear phenomena

  41. Charged multiplicities in transverse region Multiple Interactions at LHC • Models tuned to TeVatron data • give HUGE differences at LHC ... • better understand multiple interactions ... C. Buttar et al

  42. Towards understanding of MI • Cutting rules (AGK) extended to QCD • Relate diffraction, saturation and multiple scatterings • All from the same amplitude, but different factors: • +1 Diffraction • - 4 Saturation • +2 Multiple Interactions • Extended now also to pp !!!! • further work needed ... • HERA is the place to understand MI !!!! (TeVatron to tune MC !!!) • Towards the description of “everything” !!!!! Bartels, Kowalski, Sabio-Vera

  43. j1 W j2 t b-jet Multiple Interactions and top mass from M. Mangano hep-ex/04003021 Are we sure ? • Multiple Interactions • Jet fragmentation properties, jet profiles • Final state QCD radiation • B-fragmentation Significant effects on top mass determination Better understand them !!!

  44. WG1: PDFs Simple spread of existing PDFs gives up to 10% uncertainty on Higgs cross section  we have to do better than that!

  45. DGLAP evolution Q. is NLO (or NNLO) DGLAP sufficient at small x? Are higher-orders ~ αSn logm x important? CCFM? BFKL? Non-linear effects? Saturation? QCD Evolution of PDFs • At the LHC: momentum fractions x1 and x2determined by mass and rapidity of X • HERA measurements do not cover the LHC region, eg. for • central Higgs production • PDFs evolved via DGLAP equations from (x,Q20) to (x,Q2) Note: W,Z, Higgs production needs PDFs from the x range 10-4 – 10-1 Is it safe? E.g. R. Thorne: yes low-x resummations are important and can lead to >10% differences

  46. Continued this not the end • Next HERA-LHC workshop(before LHC starts) Spring 2007 at DESY (exact dates still to be decided) • informal meetings/working group weeks fall 2006 and/or Jan 2007 • Proceedings after 2007 meeting • contributed papers for 2006 are still accepted and electronically published • 2008 meeting at CERN with first results from LHC • Contributions are still possible and welcome !

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