Tevatron-for-LHC Report of the QCD Working Group

TL;DR

Tevatron Run II data enable precision QCD tests at a hadron collider, motivating a structured transfer of Tevatron expertise to the LHC. The paper aggregates results from the TeV4LHC QCD Working Group on jet definitions, PDFs (including heavy flavor), event tunes, diffractive physics, and practical measurements for early LHC analyses. It analyzes jet algorithms (cone and k_T), discusses issues such as seeds, R_sep, and infrared safety, and presents strategies for correcting non-perturbative effects like the underlying event and hadronization. It also introduces tools like LHAPDF and fastNLO for fast, uncertainty-aware calculations and stresses the importance of consistent cross‑calibration between experiments for reliable background estimates and new-physics searches at the LHC.

Abstract

The experiments at Run 2 of the Tevatron have each accumulated over 1 inverse femtobarn of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focussed on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop.

Figures (15)

• Figure 2.0.1: Dictionary of Hadron Collider Terms
• Figure 2.0.2: Impact of different jet clustering algorithms on an interesting event.
• Figure 2.0.3: Illustration of the flow of trial cones to a stable jet solution.
• Figure 2.0.4: Perturbative 2-parton phase space: $z=p_{T,2}/p_{T,1}\left( p_{T,1}\geq p_{T,2}\right)$, $d=\sqrt{\left( y_{1}-y_{2}\right) ^{2}+\left( \phi_{1}-\phi_{2}\right) ^{2}}$ for a) the naive $R_{sep}=2$ case and b) for $R_{sep}=1.3$ case suggested by data.
• Figure 2.0.5: 2-parton distribution in $\left( d,z\right)$ in a) with $d=1.0$, $z=0.6$ and the corresponding energy-in-cone, $E_{C}\left( r\right)$, and potential, $V\left( r\right)$.