The plan for a super $\eta$ factory at Huizhou accelerator complex

TL;DR

This paper proposes constructing a super eta factory at Huizhou accelerator complex to produce over 10^{13} eta mesons annually, enabling exploration of new physics, CP violation, and QCD tests.

Contribution

It introduces a novel plan for a super eta factory at HIAF or CiADS, including conceptual design and preliminary simulations for high-intensity eta meson production.

Findings

Potential to produce over 10^{13} eta events annually

Design of a spectrometer for eta decay studies

Preliminary simulation results supporting feasibility

Abstract

As an approximate Goldstone boson with zero quantum number and zero standard model charge, the decay processes of long-lived $\eta$ meson offer a unique opportunity to explore new physics beyond the standard model and new sources of CP violation, as well as test the low-energy QCD theory and measure the fundamental parameters of light quarks. To pursue these goals in the physics frontiers, we propose a plan to construct a super $\eta$ factory at HIAF high-energy terminal or at CiADS after its energy upgrade. The high-intensity proton beam at HIAF enables the production of a vast number of $\eta$ samples, exceeding $10^{13}$ events per year in the first stage, utilizing multiple layers of thin targets made of light nucleus. This paper presents the physics goals, the first-version conceptual design of the spectrometer, and some preliminary simulation results.