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1st Workshop on New Light Physics and Photon-beam Experiments

Atsushi Tokiyasu (Tohoku University), Igal Jaegle (jlab), Lena Heijkenskjöld (Johannes Gutenberg-Universität Mainz), Yiming Zhong (Kavli Institute for Cosmological Physics)

Current and future photon-beam experiments, with their unprecedented beam intensities, provide a unique opportunity to explore MeV to GeV new light particles that couple feebly to the Standard Model. The new particles can be produced through the scatterings between the beam photons and the target nucleons or electrons, or the decays of mesons.


This workshop brings together the experimental and theoretical community within this field to discuss and strategize searches for new physics as well as share common tools through 4 dedicated sessions:

- Theoretical models and predictions
- Existing and future experimental facilities
- Research & Development
- Tutorials on tools and techniques


This workshop will be held remotely via bluejeans,

  • Alexander Austregesilo
  • Atsushi Tokiyasu
  • Chandrasekhar Akondi
  • Christoph Kosi
  • Churamani Paudel
  • Daniel Aloni
  • Eugene Chudakov
  • Igal Jaegle
  • Igor Strakovsky
  • Jonathan Feng
  • Lawrence Ng
  • Lena Heijkenskjöld
  • Liping Gan
  • Mahmoud Kamel
  • Mihai Mocanu
  • Naomi Jarvis
  • peter cameron
  • Sankha Subhra Chakrabarty
  • Sean Tulin
  • Simon Taylor
  • Susan Schadmand
  • Thomas Jude
  • Tolga Erbora
  • Toshio Namba
  • Vahe Sokhoyan
  • Valery Tyukin
  • Varun Neelamana
  • William Snow
  • Yiming Zhong
  • Yunjie Yang
  • Zach Baldwin
    • 09:00 09:15
      Workshop introduction 15m
    • 09:15 10:45
      Convener: Yiming Zhong (Kavli Institute for Cosmological Physics, University of Chicago)
    • 10:45 11:00
      Coffe break 15m
    • 11:00 11:30
    • 11:30 12:00
      Coffee break 30m
    • 12:00 13:00
      • 12:00
        Status of Polarized Atomic Hydrogen Target 30m

        One aim for the new electron accelerator MESA is to measure the weak mixing angle in electron-proton scattering with high precision. This results in a requirement for beam polarization measurement of ∆P/P≈0.5%. The Møller polarimeter proposed in 2004 opens the way to reach a sufficiently accurate measurement. The polarized atomic hydrogen target is under construction. The current status including recent modifications is presented.

        Speaker: Valery Tioukine (Mainz University)
      • 12:30
        R&D possible directions 30m
        Speaker: Igal Jaegle (jlab)
    • 13:00 14:00
      Lunch break 1h
    • 14:00 16:00
      Tutorials I
      Convener: Igal Jaegle (jlab)
    • 09:00 10:30
      Experiments I
      Convener: Lena Heijkenskjöld (Johannes Gutenberg-Universität Mainz)
      • 09:00
        Axion-like particle searches at SPring-8 synchrotron facility 30m

        We performed searches for axion-like particles (ALPs) at SPring-8, one of the largest synchrotron radiation facility in the world. The searches are based on the light-shining-through-a-wall technique, and two different electromagnetic field sources, high-repetition pulsed magnets and atomic electric fields in a single crystal, are used for the photon-ALP conversion. The detail of the searches and their results will be presented.

        Speaker: Toshio Namba ( University of Tokyo)
      • 09:30
        GeV-photon beam facility and future plans in Japan 30m

        In Japan, there are some facilities where GeV-class photon beam is available. In SPring-8, LEPS/LEPS2 experiment is on-going. LEPS2 experiment is aiming to open a new field of physics by using a highly polarized photon beam from backward Compton scattering. In ELPH, FOREST experiment composed of calorimeters and a forward spectrometer is on-going.
        The property and status of each facility is reviewed, and ideas to hunt BSM are discussed.

        Speaker: Atsushi Tokiyasu (Tohoku University)
      • 10:00
        Rare Eta/Eta-Prime Neutral Modes and Beyond-Standard-Model Physics 30m

        Precision measurements of several η(′) decay channels, with emphasis on rare neutral modes, will be carried out at the Jefferson Lab Eta Factory (JEF). This experiment will employ the baseline GlueX detector at Hall D/Jefferson Lab, augmented by upgrading the central region of the electromagnetic, Forward CALorimeter (FCAL-II) and is scheduled to run in 2023-4. Copious numbers of forward-boosted η(′) mesons will be produced through the γ + p → η(′) + p reaction, using an 8-12 GeV tagged photon beam. The reaction decay particles will be measured with a high-resolution PbWO4 crystal insert in the FCAL central region that minimizes shower overlaps and optimizes the resolutions of energy and position. The combination of highly boosted eta/eta' production, recoil proton detection, and PWO insert makes JEF unique compared to other eta/eta' experiments.The JEF physics program will allow a search for new gauge bosons in portals coupling the SM sector to the dark sector in the invariant mass region below 1 GeV: a leptophobic vector boson which couples to baryon number will be sought via the π0γγ and π+π-π0 channels; a dark photon or leptophilic vector bosons could be accessible via π0e+e-; and the presence of a hadrophilic scalar and axion-like particles that couple to photons will also be probed. The rich JEF physics also includes C-violating eta(‘) decays, constraints on C-violating, P-conserving reactions, precision tests of low energy QCD [O(p6) ChPT] and Dalitz analyses to access the quark mass ratio. Details of the physics goals and an update on the experimental hardware will be presented.

        Speaker: Zisis Papandreou (University of Regina)
    • 10:30 11:00
      Coffe break 30m
    • 11:00 12:30
      Experiments II
      Convener: Atsushi Tokiyasu (Tohoku University)
      • 11:00
        Search for photoproduction of axion-like particles at GlueX 30m

        Axion-like particles (ALPs) are hypothetical pseudoscalars found in many extensions to the Standard Model. Recently, MeV-to-GeV scale, henceforth QCD-scale, ALPs have received considerable interest. We perform a dedicated search for photoproduction of QCD scale ALPs using the full GlueX Phase I dataset in the gammagamma and pi^+\pi^-\pi^0 channels. The analysis is currently blinded and under collaboration review. In this talk, we will present the general search strategy and the expected sensitivity.

        Speaker: Yunjie Yang (MIT)
      • 11:30
        New Light Physics at the A2-MAMI Experiment 30m

        The A2 tagged photon facility at the Mainz Microtron (MAMI) allows for high-precision photo-nuclear studies. The Bremsstrahlung distribution of the A2 photon beam, produced from the MAMI electron beam, covers an E_gamma range between 40 and 1604 MeV. This beam of real photons serves as a clean electromagnetic probe allowing for detailed studies of the inner properties of the nucleon as well as meson-nucleon dynamics. The experimental setup utilises a system of detectors that nearly covers the full solid angle which, together with the high flux beam, also makes the experiment a light meson factory, providing the ideal conditions for searching for new light physics in the MeV to GeV range.

        This presentation will detail the current capabilities of the A2 experimental setup as well as outline some possible searches for new physics.

        Speaker: Lena Heijkenskjöld (Johannes Gutenberg-Universität Mainz)
      • 12:00
        Parity Violation in Deuteron Photodisintegration 30m
        Speaker: William Snow (Inidiana University)
    • 12:30 13:30
      Lunch break 1h
    • 13:30 15:00
      Bump seach and limit calculation 1h 30m
    • 09:00 10:30
      Open table