EF05: QCD and strong interactions: Precision QCD

• co-Conveners: Michael Begel, Stefan Hoeche, Michael Schmitt
• Email list: SNOWMASS-EF-05-PRECISION_QCD@FNAL.GOV
  • For instructions how to join an Email list refer to Energy Frontier/Communications

This topical group covers the following: physics with jet and jet substructure, calculations of higher-order effects and their impact on precision QCD physics, measurements of the strong coupling constant and its running, measurements of quark masses, PDF fits and PDF-sensitive measurements, W/Z(+jets) boson production, and techniques to improve accuracy of future MC event generators.

There is a strong synergy with other EF groups, including EF06 and EF07 and also the TF06 group on the Theory Frontier.

If you have a topic you feel would be of interest to the group, please contact the conveners: s-hoeche@fnal.gov begel@bnl.gov m-schmitt@northwestern.edu.

Our meetings generally take place on Mondays. Recent meetings include:

• May 18, 2020: Kick-off
• June 1, 2020: Orientation: past and recent work.
• June 30, 2020: alpha_S
• July 17, 2020: MC event generator uncertainties
• Aug 3-4, 2020: Mini-workshop on non-perturbative uncertainties
• Aug 24, 2020: Letters of Intent
• Sep 21, 2020: Jet substructure
• Oct 12, 2020: LOI: alpha_S
• Oct 26, 2020: LOI: precision calculations

The general link is here.

Some (but not all) of the topics addressed by EF05:

• Measurements of alpha_S
• Parton Distribution Functions (together with E06)
• Connections between the High-Luminosity LHC and e.g. the Electron-Ion Collider (EIC) (together with EF07)
• Jet substructure
• Theoretical calculations: fixed-order pQCD
• Theoretical calculations: resummation
• Non-perturbative aspects
• MC Event Generators
• Quality of theory predictions for Higgs boson, top quark production, etc.

Other topics include Lattice QCD, Connections to machine learning, jets and nuclear effects in lepton-ion scattering, spin observables, precision calculations at small x_Bj, Regge trajectories, etc.

A number of questions are emerging from the discussions in EF05 Meetings. This is a partial list:

1. What precision in alpha_S can be reached by each future machine/experiment?
2. The HEP and EIC communities should develop some joint benchmarks for PDFs. (EIC accesses high x_Bj)
3. What is the evolution of jets as a function of energy at the EIC and at hadron colliders? What can EIC jet studies learn from techniques developed at the LHC?
4. Are jets universal? How can we tell? If not, how do we deal with non-universality in our hadronization models?
5. How can we get more precise and robust systematic uncertainties? How do experimental and theoretical uncertainties mix?
6. What is a theoretical uncertainty (e.g. renormalization and factorization scales)? How can “theoretical” uncertainties reported by experimentalists be decorrelated so that they can properly be taken into account?
7. It is important to explore PDFs coming from lattice calculations. Does the traditional PDF community need to provide guidance?
8. We need a “Les Houches” accord on a realistic assessment of parton shower uncertainties (and correlations). There are new ideas from the theory community about how to formulate these uncertainties.
9. How do we keep separate tuning of ostensibly non-perturbative parameters such as h_damp from perturbative physics which should be essentially parameter-free?
10. What can we learn about non-perturbative physics using minimum-bias events at the LHC?
11. How can we promote the analysis of Belle data to provide crucial information on non-perturbative QCD?
12. What information (if any) can be extracted from neutrino data - i.e., data used to calibrate beam fluxes?
13. Which spectra and measurements are most useful for constraining non-perturbative effects?
14. What is a better way to analyze and study multiple-parton interactions (and the underlying event)?
15. Can the community provide an informal rating of MC event generators? What would be the basis for such a rating?

The plan for generating and organizing Monte Carlo event samples comes from the Monte Carlo Task Force led by John Stupak.

Researchers with interests in precision QCD should contact the organizers to arrange a presentation or contribution.

Activities will be grouped around several Letters of Interest. The portal for submitting an LOI is here.

Letters of Intent submitted to Energy Frontier (as primary frontier) shown in this link. Here is the list of submitted LOIs that include EF as primary or secondary topic. First index before “/” corresponds to the primary frontier used for the submission.