English

Status of the PrimEx $\eta$ experiment at Jefferson Lab

Nuclear Experiment 2025-10-07 v1

Abstract

The GlueX detector in the experimental Hall DD at Jefferson Lab offers a unique opportunity to perform a measurement of the decay width of eta mesons through the Primakoff effect. The PrimEx η\eta experiment complements the physics program at Jefferson Lab on measuring the decay width of light pseudoscalar mesons via the Primakoff process. The goal of PrimEx η\eta is to measure differential cross sections of η\eta mesons at forward angles using a beam of tagged photons incident on a liquid 4He{}^{4}{\rm He} target. The data will be used for the extraction of the decay width. This measurement is vital for understanding fundamental properties like the ratios of the light quark masses and the η\eta-η\eta^\prime mixing angle, and will provide an important test of chiral symmetry breaking in QCD. Our experimental results will help reduce uncertainties on partial widths of all other η\eta decays. The experiment collected data during three physics runs between 2019 and 2022. We will give an overview of the PrimEx η\eta experiment and the current status of our data analyses. We will also discuss the feasibility of conducting future Primakoff measurements in light of the recent upgrade of the GlueX forward calorimeter and the potential accelerator energy upgrade to 22 GeV.

Keywords

Cite

@article{arxiv.2510.04324,
  title  = {Status of the PrimEx $\eta$ experiment at Jefferson Lab},
  author = {Alexander Somov},
  journal= {arXiv preprint arXiv:2510.04324},
  year   = {2025}
}

Comments

15 pages, 15 figures; contribution to the 11th International Workshop on Chiral Dynamics (CD2024). To be published in PoS, volume 479. as (CD2024)073