3rd Proton Mass Workshop: Origin and Perspective

Welcome

Ian Cloet

Argonne National Laboratory

Organizers: Ian Cloet, Xiangdong Ji, Zein-Eddine Meziani, and Jianwei Qiu

14−16 January 2021

Why are we here?

Derek Leinweber (Adelaide)

• We are here to discuss one of the most fundamental questions in

strong interaction physics: How does the proton get its mass?

• Intimately connected to the origin of the visible

universe

• The proton contains an uncountable number

of quarks, anti-quarks, and gluons

• However, even if the quarks are massless (chiral

limit) the proton only gets around 5% lighter

(sigma terms)

• The proton gets the vast bulk of its mass from the field energies of the

quarks and gluons it contains

• Deeply connected with emergent phenomena of color confinement and

dynamical chiral symmetry breaking – entwined with the trace anomaly⟨N��T `

`

��N⟩= 2m2

N ,⟨𝜋��T `

`

��𝜋⟩ = 2m2𝜋

chiral limit−→ 0

Finding the Right Questions

• Progress can be accelerated and focused with the right questions.

Formulating and refining these questions is a goal for the meeting.

• On the workshop website we have outlined many related questions:

• What determines the QCD scale and how does it affect the visible

universe?

• What is the role of the trace anomaly in QCD? Does it reflect both

color confinement and dimensional transmutation?

• What is the role and interplay between chiral symmetry breaking and

color confinement in determining hadron masses?

• Can nucleon TMDs reveal the temperature at which

the nucleon is formed?

• What is the interplay between the Higgs and QCD

mass generation mechanisms?

• Can lattice QCD calculate the mass distribution in

the nucleon?

• These questions need to be distilled and likely new

questions added

How did we get here?

The 1st proton mass workshop “The Proton Mass: At the heart

of most visible matter” was held at Temple University on 28-29

March 2016. Organizers: Zein-Eddine Meziani and Jianwei Qiu

https://phys.cst.temple.edu/~meziani/proton-mass-workshop-2016

ECT*EUROPEAN CENTRE FOR THEORETICAL STUDIES

IN NUCLEAR PHYSICS AND RELATED AREASTRENTO, ITALY

Institutional Member of the European Expert Committee NUPECC

Castello di Trento (“Trint”), watercolor 19.8 x 27.7, painted by A. Dürer on his way back from Venice (1495). British Museum, London

The Proton Mass: At the Heart of Most Visible MatterTrento, April 3 - 7, 2017

Main TopicsHadron mass decomposition in terms of constituents:

Uniqueness of the decomposition, Quark mass, and quark and gluon energy contribution, Anomaly contribution, ...Hadron mass calculations:

Lattice QCD (total & individual mass components), Approximated analytical methods, Phenomenological model approaches, ...Experimental access to hadron mass components:

Exclusive heavy quarkonium production at threshold, nuclear gluonometry through polarized nuclear structure function, …

Confirmed speakers and participantsAlexandrou Constantia (Cyprus University), Brodsky Stan (SLAC), Burkardt Matthias (New Mexico State University), Chen Jian-Ping (Jefferson Lab),

Chudakov Eugene (Jefferson Lab), Cloët Ian (Argonne National Lab), de Teramond Guy (University Costa Rica), Deshpande Abhay (Stony Brook University), Eichmann Gernot (Giessen University), Hafidi Kawtar (Argonne National Lab), Hoelbling Christian (University of Wuppertal), Lin Huey-Wen (Michigan State University),

Liu Keh-Fei (University of Kentucky), Lorcé Cédric (École Polytechnique, Palaiseau), Mulders Piet (Vrije University of Amsterdam), Papavassiliou Joannis (Valencia University), Pascalutsa Vladimir (Johannes Gutenberg University of Mainz), Richards David (Jefferson Lab), Roberts Craig (Argonne National Lab),

Slifer Karl (University of New Hampshire), Mauro Anselmino (University of Torino & INFN), Bob Jaffe (Massachusetts Institute of Technology), Dima Kharzeev (Stony Brook University), Xiangdong Ji (University of Maryland).

Organizers Zein-Eddine Meziani (Temple University)

Barbara Pasquini (University of Pavia)Jianwei Qiu (Jefferson Lab)

Marc Vanderhaeghen (Universität Mainz)

Director of the ECT*: Professor Jochen Wambach (ECT*)

The ECT* is sponsored by the “Fondazione Bruno Kessler” in collaboration with the “Assessorato alla Cultura” (Provincia Autonoma di Trento),funding agencies of EU Member and Associated States and has the support of the Department of Physics of the University of Trento.

For local organization please contact: Gianmaria Ziglio - ECT* Secretariat - Villa Tambosi - Strada delle Tabarelle 286 - 38123 Villazzano (Trento) - ItalyTel.:(+39-0461) 314721 Fax:(+39-0461) 314750, E-mail: ect@ectstar.eu or visit http://www.ectstar.eu

The 2nd proton mass

workshop was held at

the ECT* on 3-7 April

2017. Organizers:

Zein-Eddine Meziani,

Barbara Pasquini,

Jianwei Qiu, and Marc

Vanderhaeghen

https://indico.jlab.

org/event/194/overview

NAS Assessment of a U.S.

based Electron Ion Collider

identified three high-priority

science questions (2018):

How does the mass of the nu-

cleon arise?

How does the spin of the nu-

cleon arise?

What are the emergent proper-

ties of dense systems of gluons?

Where are we going?

We will hold the 4th proton mass workshop at the Institute for Nuclear

Physics, titled Origin of the Visible Universe: Unraveling the Proton

Mass (20-77W), on 6-10 December 2021 [postponed from May 2020].

Organizers: Ian Cloet, Zein-Eddine Meziani, and Barbara Pasquini.

https://www.int.washington.edu/PROGRAMS/20-77W/

• A key goal of this workshop is to produce a White Paper

with the working title “Proton Mass: Origin and Perspective”

• We have a standing invitation to publish in the journal Report

on Progress in Physics

• The following people have agreed to serve as an Editor and

contribute to this publication: Constantia Alexandrou, Ian Cloet,

Xiangdong Ji, Dima Kharzeev, Zein-Eddine Meziani, Jen-Chieh

Peng, Jianwei Qiu, & Marc Vanderhaeghen

• We invite you to contribute a one-page write-up on your research and ideas related to the origin

of hadron mass. More on this at the end of the workshop. In the meantime, we invite you to send

key question(s) that you think best illuminate the origin of the proton mass (icloet@anl.gov)