Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

QCD

S. Catani, M. Dittmar, D. Soper, W. J. Stirling, S. Tapprogge, S. Alekhin, P. Aurenche, C. Balazs, R. D. Ball, G. Battistoni, E. L. Berger, T. Binoth, R. Brock, D. Casey, G. Corcella, V. Del Duca, A. Del Fabbro, A. De Roeck, C. Ewerz, D. de Florian, M. Fontannaz, S. Frixione, W. T. Giele, M. Grazzini, J. P. Guillet, G. Heinrich, J. Huston, J. Kalk, A. L. Kataev, K. Kato, S. Keller, M. Klasen, D. A. Kosower, A. Kulesza, Z. Kunszt, A. Kupco V. A. Ilyin, L. Magnea, M. L. Mangano, A. D. Martin, K. Mazumdar, Ph. Mine, M. Moretti, W. L. van Neerven, G. Parente, D. Perret-Gallix, E. Pilon, A. E. Pukhov, I. Puljak, J. Pumplin, E. Richter-Was, R. G. Roberts, G. P. Salam, M. H. Seymour, N. Skachkov, A. V. Sidorov, H. Stenzel, D. Stump, R. S. Thorne, D. Treleani, W. K. Tung, A. Vogt, B. R. Webber, M. Werlen, S. Zmouchko

TL;DR

The paper surveys QCD issues relevant for the LHC, focusing on how parton distributions, higher-order calculations, resummation, and Monte Carlo tools shape predictions and experimental analyses. It emphasizes the factorization framework, the perturbative expansion in αS, and the evolution of PDFs via DGLAP, along with the importance of scale and scheme choices. It discusses current progress and challenges in NLO/NNLO calculations, resummation techniques, and backgrounds to Higgs production, plus the role of small-x dynamics and double parton scattering. The work also highlights pragmatic approaches to PDF uncertainties and the way LHC data can constrain PDFs, setting a reference for theoretical and experimental efforts leading into LHC data-taking. Overall, it provides a comprehensive reference for the QCD toolkit and its application to LHC phenomenology.

Abstract

We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics, double parton scattering, and backgrounds to Higgs production.

QCD

TL;DR

The paper surveys QCD issues relevant for the LHC, focusing on how parton distributions, higher-order calculations, resummation, and Monte Carlo tools shape predictions and experimental analyses. It emphasizes the factorization framework, the perturbative expansion in αS, and the evolution of PDFs via DGLAP, along with the importance of scale and scheme choices. It discusses current progress and challenges in NLO/NNLO calculations, resummation techniques, and backgrounds to Higgs production, plus the role of small-x dynamics and double parton scattering. The work also highlights pragmatic approaches to PDF uncertainties and the way LHC data can constrain PDFs, setting a reference for theoretical and experimental efforts leading into LHC data-taking. Overall, it provides a comprehensive reference for the QCD toolkit and its application to LHC phenomenology.

Abstract

We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics, double parton scattering, and backgrounds to Higgs production.

Paper Structure

This paper contains 4 sections, 11 equations, 6 figures.

Table of Contents

  1. INTRODUCTION
  2. Overview of QCD tools
  3. PARTON DISTRIBUTION FUNCTIONS
  4. MRS: pdf uncertainties and $W$ and $Z$ production at the LHC

Figures (6)

  • Figure 1: Jet cross section at the LHC, averaged over the rapidity interval $-1<y<1$. The cross section is calculated at NLO using CTEQ5M partons with the renormalization and factorization scales set to $\mu_R = \mu_F = E_T/2$. Representative values at $E_T =$0.5, 1, 2, 3 and 4 TeV are $( 6.2 \times 10^{3}, 8.3 \times 10^{1}, 4.0 \times 10^{-1}, 5.1 \times 10^{-3}, 5.9 \times 10^{-5} )$ fb/GeV with about 3% statistical errors.
  • Figure 2: Values of $x$ and $Q^2$ probed in the production of an object of mass $M$ and rapidity $y$ at the LHC, $\sqrt{s} = 14$ TeV.
  • Figure 3: Cross sections for hard scattering versus $\sqrt{s}$. The cross section values at $\sqrt{s} = 14$ TeV are: $\sigma_{\rm tot} = 99.4$ mb, $\sigma_{\rm b} = 0.633$ mb, $\sigma_{\rm t} = 0.888$ nb, $\sigma_{\rm W} = 187$ nb, $\sigma_{\rm Z} = 55.5$ nb, $\sigma_{{\rm H}}(M_{\rm H} =150\;{\rm GeV}) = 23.8$ pb, $\sigma_{{\rm H}}(M_{\rm H} =500\;{\rm GeV}) = 3.82$ pb, $\sigma_{{\rm jet}}(E_T^{\rm jet}> 100\;{\rm GeV}) = 1.57\; \mu$b, $\sigma_{{\rm jet}}(E_T^{\rm jet}> \sqrt{s}/20) = 0.133$ nb, $\sigma_{{\rm jet}}(E_T^{\rm jet}> \sqrt{s}/4) = 0.10$ fb. All except the first of these are calculated using the latest MRST pdf's Martin:1999ww.
  • Figure 4: Variation of the jet cross section with renormalization and factorization scale. We show $\Delta$ defined in Eq. (\ref{['DeltaDef']}) versus $E_T$ for four choices of $\{\mu_{R}/E_T, \mu_{F}/E_T\}$.
  • Figure 5: Schematic representation of the various uncertainties contributing to the prediction of a structure function or parton distribution at high $Q^2$.
  • ...and 1 more figures