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Les Houches Physics at TeV Colliders 2005, Standard Model and Higgs working group: Summary report

C. Buttar, S. Dittmaier, V. Drollinger, S. Frixione, A. Nikitenko, S. Willenbrock S. Abdullin, E. Accomando, D. Acosta, A. Arbuzov, R. D. Ball, A. Ballestrero, P. Bartalini, U. Baur, A. Belhouari, S. Belov, A. Belyaev, D. Benedetti, T. Binoth, S. Bolognesi, S. Bondarenko, E. E. Boos, F. Boudjema, A. Bredenstein, V. E. Bunichev, C. Buttar, J. M. Campbell, C. Carloni Calame, S. Catani, R. Cavanaugh, M. Ciccolini, J. Collins, A. M. Cooper-Sarkar, G. Corcella, S. Cucciarelli, G. Davatz, V. DelDuca, A. Denner, J. D'Hondt, S. Dittmaier, V. Drollinger, A. Drozdetskiy, L. V. Dudko, M. Duehrssen, R. Frazier, S. Frixione, J. Fujimoto, S. Gascon-Shotkin, T. Gehrmann, A. Gehrmann-De Ridder, A. Giammanco, A. -S. Giolo-Nicollerat, E. W. N. Glover, R. M. Godbole, A. Grau, M. Grazzini, J. -Ph. Guillet, A. Gusev, R. Harlander, R. Hegde, G. Heinrich, J. Heyninck, J. Huston, T. Ishikawa, A. Kalinowski, T. Kaneko, K. Kato, N. Kauer, W. Kilgore, M. Kirsanov, A. Korytov, M. Kraemer, A. Kulesza, Y. Kurihara, S. Lehti, L. Magnea, F. Mahmoudi, E. Maina, F. Maltoni, C. Mariotti, B. Mellado, D. Mercier, G. Mitselmakher, G. Montagna, A. Moraes, M. Moretti, S. Moretti, I. Nakano, P. Nason, O. Nicrosini, A. Nikitenko, M. R. Nolten, F. Olness, Yu. Pakhotin, G. Pancheri, F. Piccinini, E. Pilon, R. Pittau, S. Pozzorini, J. Pumplin, W. Quayle, D. A. Ross, R. Sadykov, M. Sandhoff, V. I. Savrin, A. Schmidt, M. Schulze, S. Schumann, B. Scurlock, A. Sherstnev, P. Skands, G. Somogyi, J. Smith, M. Spira, Y. Srivastava, H. Stenzel, Y. Sumino, R. Tanaka, Z. Trocsanyi, S. Tsuno, A. Vicini, D. Wackeroth, M. M. Weber, C. Weiser, S. Willenbrock, S. L. Wu, M. Zanetti

TL;DR

The report assesses Standard Model benchmarks and Higgs-related channels for the LHC, emphasizing standard candles (W, Z, tt̄) and nonperturbative inputs (PDFs, Underlying Event) to calibrate simulations and backgrounds. It surveys total cross-section predictions at LHC from Regge/Pomeron and mini-jet eikonal models, and provides a unified view of theoretical uncertainties with practical parameterizations. The sections on minimum-bias and underlying-event tuning (PYTHIA/JIMMY) compare to data and deliver LHC-ready tunes, while the small-x discussion analyzes the impact of PDFs, resummation, and potential BFKL effects on W/Z production at large rapidities. Overall, the work delivers calibrated predictions and tunings vital for robust Higgs searches and detector-level analyses at the LHC.

Abstract

This Report summarises the activities of the "SM and Higgs" working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. On the one hand, we performed a variety of experimental and theoretical studies on standard candles (such as W, Z, and ttbar production), treating them either as proper signals of known physics, or as backgrounds to unknown physics; we also addressed issues relevant to those non-perturbative or semi-perturbative ingredients, such as Parton Density Functions and Underlying Events, whose understanding will be crucial for a proper simulation of the actual events taking place in the detectors. On the other hand, several channels for the production of the Higgs, or involving the Higgs, have been considered in some detail. The report is structured into four main parts. The first one deals with Standard Model physics, except the Higgs. A variety of arguments are treated here, from full simulation of processes constituting a background to Higgs production, to studies of uncertainties due to PDFs and to extrapolations of models for underlying events, from small-$x$ issues to electroweak corrections which may play a role in vector boson physics. The second part of the report treats Higgs physics from the point of view of the signal. In the third part, reviews are presented on the current status of multi-leg, next-to-leading order and of next-to-next-to-leading order QCD computations. Finally, the fourth part deals with the use of Monte Carlos for simulation of LHC physics.

Les Houches Physics at TeV Colliders 2005, Standard Model and Higgs working group: Summary report

TL;DR

The report assesses Standard Model benchmarks and Higgs-related channels for the LHC, emphasizing standard candles (W, Z, tt̄) and nonperturbative inputs (PDFs, Underlying Event) to calibrate simulations and backgrounds. It surveys total cross-section predictions at LHC from Regge/Pomeron and mini-jet eikonal models, and provides a unified view of theoretical uncertainties with practical parameterizations. The sections on minimum-bias and underlying-event tuning (PYTHIA/JIMMY) compare to data and deliver LHC-ready tunes, while the small-x discussion analyzes the impact of PDFs, resummation, and potential BFKL effects on W/Z production at large rapidities. Overall, the work delivers calibrated predictions and tunings vital for robust Higgs searches and detector-level analyses at the LHC.

Abstract

This Report summarises the activities of the "SM and Higgs" working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. On the one hand, we performed a variety of experimental and theoretical studies on standard candles (such as W, Z, and ttbar production), treating them either as proper signals of known physics, or as backgrounds to unknown physics; we also addressed issues relevant to those non-perturbative or semi-perturbative ingredients, such as Parton Density Functions and Underlying Events, whose understanding will be crucial for a proper simulation of the actual events taking place in the detectors. On the other hand, several channels for the production of the Higgs, or involving the Higgs, have been considered in some detail. The report is structured into four main parts. The first one deals with Standard Model physics, except the Higgs. A variety of arguments are treated here, from full simulation of processes constituting a background to Higgs production, to studies of uncertainties due to PDFs and to extrapolations of models for underlying events, from small- issues to electroweak corrections which may play a role in vector boson physics. The second part of the report treats Higgs physics from the point of view of the signal. In the third part, reviews are presented on the current status of multi-leg, next-to-leading order and of next-to-next-to-leading order QCD computations. Finally, the fourth part deals with the use of Monte Carlos for simulation of LHC physics.

Paper Structure

This paper contains 20 sections, 13 equations, 7 figures, 4 tables.

Table of Contents

  1. FOREWORD
  2. STANDARD MODEL BENCHMARKS AND BACKGROUNDS
  3. MODEL PREDICTIONS FOR $\sigma^{\rm tot}$ AT THE LHC
  4. Introduction
  5. Phenomenological models
  6. Model predictions for $\sigma_{\rm tot}^{\rm pp}$ at the LHC
  7. Conclusions
  8. TUNING MODELS FOR MINIMUM BIAS AND THE UNDERLYING EVENT
  9. Introduction
  10. Minimum bias events
  11. Predictions vs. minimum bias data
  12. LHC predictions for minimum bias events
  13. Underlying event
  14. JIMMY4.1 tuning
  15. Predictions vs. UE data
  16. ...and 5 more sections

Figures (7)

  • Figure 1: Predictions for $\sigma_{\rm tot}^{\rm pp}$ in various models. The shaded area gives the range of results in the Eikonalised mini-jet model with soft gluon resummation Godbole:2004kx (the G.G.P.S. model) the solid line giving the prediction obtained using the GRV parton densities Gluck:1991ng in the model. The long-dashed dotted curve ($d$), indicates the predictions for the DL fit Donnachie:1992ny. The dotted (BH) curve ($c$) and the uppermost dashed curve ($a$), are the results of two analytical models incoporating constraints from unitarity and analyticity, from Block:2005ka and Avila:2002tk, respectively. The prediction obtained by Igi et al, using FESR follows very closely that given by the BH curve. The short dash dotted curve ($b$), is the result of a fit by the COMPETE collaboration Cudell:2002xe.
  • Figure 2: (a) Charged multiplicity distributions for NSD p$\overline{\rm{p}}$ collisions at $\sqrt{\rm{s}}$ = 900 GeV; (b) dN$_{ch}$/d$\eta$ for NSD p$\overline{\rm{p}}$ collisions at 1.8 TeV; (c) dN$_{ch}$/d$\eta$ at $\eta =0$ for a wide range of $\sqrt{\rm{s}}$ shown for PYTHIA6.214 - Rome and PYTHIA6.323 - Min-bias and (d) average charged particles multiplicity in the UE compared to CDF data.
  • Figure 3: (a) Charged particle density distributions, dN$_{ch}$/d$\eta$, for NSD pp collisions at $\sqrt{\rm{s}}$ = 14 TeV. Predictions generated by PYTHIA6.214 - ATLAS and PYTHIA6.323 - Min-bias. (b) Charged particle p$_{t}$ spectrum for NSD pp collisions at $\sqrt{\rm{s}}$ = 14 TeV.
  • Figure 4: PYTHIA6.323 - UE predictions for the UE compared to the $<p_{t}>$ in MAX and MIN cones for (a) p$\overline{\rm{p}}$ collisions at $\sqrt{\rm{s}}$ = 630 GeV and (b) 1.8 TeV.
  • Figure 5: JIMMY4.1 - UE predictions for the UE compared to the $<p_{t}>$ in MAX and MIN cones for (a) p$\overline{\rm{p}}$ collisions at $\sqrt{\rm{s}}$ = 630 GeV and (b) 1.8 TeV.
  • ...and 2 more figures