3rd Proton Mass Workshop; Origin and Perspective

America/New_York
Virtual (Argonne National Laboratory)

Virtual

Argonne National Laboratory

Physics Division Bdg. 203 9700 South Cass Avenue Argonne, IL 60439
Ian CLOËT (Argonne National Laboratory), Xiangdong JI (University of Maryland), Zein-Eddine MEZIANI (Argonne National Laboratory), Jianwei QIU (Jefferson Lab)
Description

The next major facility construction in the US is the Electron-Ion Collider planned at Brookhaven National Laboratory. A science assessment by the National Academy of Sciences (https://www.nap.edu/catalog/25171/an-assessment-of-us-based-electron-ion-collider-science) found three central questions that the facility should address, and among these is "How does the mass of the nucleon arise?"

This question goes to the essence of QCD and embodies many of its mysteries and emergent phenomena, such as color confinement. Its understanding is fundamental to the future of nuclear physics, and we think that addressing this question within QCD will expose deep connections and significantly impact the broader fields of cosmology, particle physics, condensed matter, and biology.

In the spirit of the questions posed by Hilbert in the 1900 Mathematics Congress and the Millennium Prize Problems in Mathematical Physics, we would like to identify key theoretical questions to further inform and guide the science program of the Electron-Ion Collider. Our hope is that by posing the right questions this workshop can have a lasting impact on our understanding of the visible universe.

More broadly, this workshop will address and hone key questions related to the proton mass. It is organized around four interelated areas which include the broader fields of physics, the fundamentals of QCD, lattice calculations, hadron models, and last but not least to  experiments and specific observables.

A sample of questions includes:

  1. Broader questions
    1. The nucleon mass is the most crucial gravitational charge in the universe below the scale of galaxies. How does the strong interaction scale or mass affect the visible universe?
    2. Can the nucleon's transverse momentum parton distributions reveal the temperature at which the nucleon is formed?
    3. What determines the QCD scale?
    4. What does QCD dynamics predict about the proton mass if the scale is just a parameter?
    5. How would the physical world (condensed matter, chemistry, and biology) change if Λ_QCD is increased or decreased by a factor of 2?
    6. What is the interplay between the Higgs and QCD mass generation mechanisms?
  2. Fundamentals of QCD
    1. What is the role of the trace anomaly in QCD? Does it reflect both color confinement and dimensional transmutation?
    2. What is the role of chiral symmetry breaking (CSB) in determining the nucleon mass? What is the interplay between the CSB and color confinement?
    3. Why are the nucleon resonances (with change of spin and isospin) separated by a large mass gap? 
    4. Can a relativistic Virial theorem tell us something deeper about the origin of mass?
  3. Lattice QCD calculations questions
    1. Can one calculate the anomaly contribution on the lattice?
    2. Can the lattice calculate the mass distribution in the nucleon?
    3. Why is the color magnetic field depleted inside the proton?
    4. How does the kinetic energy of quarks balance the color confinement energy of the gluon?
    5. Should a glue ball mass be lighter or heavier than the proton mass or 2 pions mass? If so why?
  4. Hadron models questions
    1. What is the relation between the trace anomaly and the MIT bag constant?
    2. Can AdS/CFT models tell us something deep about the proton mass?
    3. Can 2D models, or simple 4D models (sigma model, NJL model, etc.) tell us something about the mass?
    4. What is the interplay of the Higgs mechanism and QCD mass generation for the mass of hadrons (meson, baryons, XYZ, etc.) with heavy flavors?
Paula Dahlberg (Workshop Coordinator)
Participants
    • 9:45 AM 12:35 PM
      Thursday Morning
      Convener: Dr Ian CLOËT (Argonne National Laboratory)
      • 9:45 AM
        Welcome 15m
        Speaker: Ian CLOËT (Argonne National Laboratory)
      • 10:00 AM
        Questions about nucleon mass 25m
        Speaker: Prof. Xiangdong JI (University of Maryland)
      • 10:25 AM
        Two-dimensional models for QCD 25m
        Speaker: Prof. Igor KLEBANOV (Princeton University)
      • 10:50 AM
        Coffee break/Discussion 15m
      • 11:05 AM
        Quark masses 25m
        Speaker: Dr Andreas KRONFELD (Fermilab)
      • 11:30 AM
        J/Psi photoproduction near threshold and the proton mass distribution 25m
        Speaker: Prof. Dmitri KHARZEEV (Stony Brook & BNL)
      • 11:55 AM
        Discussion and short contributions 40m
    • 12:35 PM 2:00 PM
      Lunch Break 1h 25m
    • 2:00 PM 5:00 PM
      Thursday Afternoon
      Convener: Prof. Xiangdong JI (University of Maryland)
      Contributions
      • 2:00 PM
        Mechanical properties of particles 25m
        Speaker: Prof. Maxim POLYAKOV (Bochum University)
      • 2:25 PM
        Topological origin of the hadronic mass 25m
        Speaker: Prof. Ismail ZAHED (Stony Brook University)
      • 2:50 PM
        Coffee break/Discussion 15m
      • 3:05 PM
        Decomposition of proton mass and rest energy 25m
        Speaker: Prof. Keh-Fei LIU (University of Kentucky)
      • 3:30 PM
        The proton mass from first principles: lattice QCD at the physical point 25m
        Speaker: Prof. Martha CONSTANTINOU (Temple University)
      • 3:55 PM
        Model studies of energy-momentum tensor and mechanical properties 25m
        Speaker: Prof. Peter SCHWEITZER (University of Connecticut)
      • 4:20 PM
        Discussion and short contributions 40m
    • 10:00 AM 1:00 PM
      Friday Morning
      Convener: Dr Jianwei QIU (Jefferson Laboratory)
      • 10:00 AM
        Protons in Perspective 25m
        Speaker: Prof. Mikhail SHIFMAN (University of Minesota)
      • 10:25 AM
        Insights into hadron structure from superconformal light-front holographic QCD 25m
        Speaker: Prof. Guy DE TERAMOND (University of Costa Rica)
      • 10:50 AM
        Coffee break/Discussion 15m
      • 11:05 AM
        The physical meaning of the various mass decompositions 25m
        Speaker: Prof. Cédric LORCÉ (Ecole Polytechnique)
      • 11:30 AM
        Energy-Momentum Tensor form factors for QED, a one-loop example 25m
        Speaker: Mr Simone RODINI (University of Pavia)
      • 11:55 AM
        Mass sum rules for the proton 25m
        Speaker: Prof. Andreas METZ (Temple University)
      • 12:20 PM
        Discussion and short contributions 40m
    • 1:00 PM 2:15 PM
      Lunch break 1h 15m
    • 2:15 PM 5:15 PM
      Friday Afternoon
      Convener: Dr Andreas KRONFELD (Fermilab)
      Contributions
      • 2:15 PM
        Towards the proton mass decomposition from lattice QCD 25m
        Speaker: Prof. Constantia ALEXANDROU (University of Cyprus)
      • 2:40 PM
        A view on the proton mass: Sigma terms, the trace anomaly and all that 25m
        Speaker: Prof. Ulf-G. MEISSNER (University of Bonn/FZ Jülich)
      • 3:05 PM
        Coffee break/Discussion 15m
      • 3:20 PM
        Quantum anomalous energy effects on the nucleon mass 25m
        Speaker: Dr Yizhuang LIU (Regensberg)
      • 3:45 PM
        From Nucleon to Nuclear Structure and Neutron Stars 25m
        Speaker: Prof. Anthony THOMAS (University of Adelaide)
      • 4:10 PM
        Energy-momentum tensor in static-quark systems on the lattice 25m
        Speaker: Prof. Masakiyo KITAZAWA (University of Osaka)
      • 4:35 PM
        Discussion and short contributions 40m