LHC HI WG: physics with heavy ions at the LHC

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The LHC Heavy Ion Working Group (LHC HI WG) provides a framework for the structured discussion of topics relevant to the LHC heavy ion physics programme, gathering members of the LHC experiments and the theory community. The goals of the working group are to:

  • Facilitate communication between the experimental and theoretical HI communities, assisting the interpretation of the data and the understanding of common theoretical and experimental systematics.
  • Improve the uniformity of analysis choices, leading to a more direct comparability of experimental heavy-ion results by the LHC experiments.
  • Organize systematic comparisons of measurements and the associated physics discussions, providing recommendations to experiments on how best to present the results and facilitate their reinterpretation.
  • Evaluate the need of, and prepare the ground for, possible combinations of analyses from different experiments. Such combinations would emerge from the initiative of the experiments, and would then be carried out under their responsibility.

The steering group (SG) of the LHC HI WG consists of experimental and theory conveners. Each experiment will appoint up to two conveners, joined by up to 2 theorists. The mandate of the conveners is two years, renewable once, and staggering among outgoing/incoming and continuing conveners is encouraged. The LHC HI WG operates by holding public meetings where all relevant topics are discussed. Smaller meetings with a specific focus may be scheduled, and subgroups may be formed as deemed necessary by the SG. The subgroups would report on their activities in the plenary meetings. A special case is that of possible combinations or comparisons of experimental data, and these would be organized under the direct responsibility of the involved experiments.

The WG activities will also benefit from the interaction with the HonexComb initiative, which is part of the Strong 2020 project.

WG documents and meeting agendas: see links in the right menu


  • ALICE: Alexander Kalweit and Marta Verweij
  • ATLAS: Iwona Grabowska-Bold and Jiangyong Jia
  • CMS: Raphael Granier de Cassagnac and Yi Chen
  • LHCb: Giulia Manca and Benjamin Audurier
  • Theory: Liliana Apolinario and Urs Wiedemann
  • Reach all through lhc-hiwg-admin@cern.ch