====== 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 [[https://snowmass21.org/energy/start#communications| Energy Frontier/Communications]]
~~NOCACHE~~
===== Description=====
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 [[energy:EF06]] and [[energy:EF07]] and also the [[https://snowmass21.org/theory/precision|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>.

=====Meetings=====

Our meetings generally take place on Mondays.  Recent meetings include:
  * May 18, 2020: [[https://indico.fnal.gov/event/43273/|Kick-off]]
  * June 1, 2020: [[https://indico.fnal.gov/event/43488/|Orientation: past and recent work.]]
  * June 30, 2020: [[https://indico.fnal.gov/event/43490/|alpha_S]]
  * July 17,  2020: [[https://indico.fnal.gov/event/44315/|MC  event  generator uncertainties]]
  * Aug  3-4, 2020: [[https://indico.fnal.gov/event/44316/|Mini-workshop on non-perturbative uncertainties]]
  * Aug 24, 2020: [[https://indico.fnal.gov/event/45073/|Letters of Intent]]
  * Sep 21, 2020: [[https://indico.fnal.gov/event/45614/|Jet substructure]]
  * Oct 12, 2020: [[https://indico.fnal.gov/event/45893/|LOI: alpha_S]]
  * Oct 26, 2020: [[https://indico.fnal.gov/event/46101/|LOI: precision calculations]]

The general link is [[https://indico.fnal.gov/category/1139/|here]].
=====Topics=====

Some (but not all) of the topics addressed by EF05:
   * Measurements of alpha<sub>S</sub>
   * Parton Distribution Functions (together with [[energy:E06]])
   * Connections between the High-Luminosity LHC and e.g. the Electron-Ion Collider (EIC) (together with [[energy: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<sub>Bj</sub>, Regge trajectories, etc.

=====Big Questions / Topics for Study=====

A number of questions are emerging from the discussions in [[https://indico.fnal.gov/category/1139/|EF05 Meetings]].  This is a partial list:
  - What precision in alpha<sub>S</sub> can be reached by each future machine/experiment?
  - The HEP and EIC communities should develop some joint benchmarks for PDFs.  (EIC accesses high x<sub>Bj</sub>)
  - 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?
  - Are jets universal?  How can we tell?  If not, how do we deal with non-universality in our hadronization models?
  - How can we get more precise and robust systematic uncertainties?  How do experimental and theoretical uncertainties mix?
  - 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?
  - It is important to explore PDFs coming from lattice calculations.  Does the traditional PDF community need to provide guidance?
  - 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.
  - How do we keep separate tuning of ostensibly non-perturbative parameters such as h<sub>damp</sub> from perturbative physics which should be essentially parameter-free?
  - What can we learn about non-perturbative physics using minimum-bias events at the LHC?
  - How can we promote the analysis of Belle data to provide crucial information on non-perturbative QCD?
  - What information (if any) can be extracted from neutrino data - i.e., data used to calibrate beam fluxes?
  - Which spectra and measurements are most useful for constraining non-perturbative effects?
  - What is a better way to analyze and study multiple-parton interactions (and the underlying event)?
  - Can the community provide an informal rating of MC event generators?  What would be the basis for such a rating?
  - 
====Monte Carlo event samples====

The plan for generating and organizing Monte Carlo event samples comes from the [[montecarlo:energy|Monte Carlo Task Force]] led by John Stupak.


=====Getting Involved=====

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 [[https://snowmass21.org/loi|here]].


===== Submitted LOI =====
Letters of Intent submitted to Energy Frontier (as primary frontier) [[https://www.snowmass21.org/docs/files/?dir=summaries/EF| 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.
 {{url>https://www.snowmass21.org/docs/files/list.php?frontier=EF5  border 100%,1200px}}