Very Asymmetric Collider for Dark Matter Search below 1 GeV

TL;DR

This paper proposes a novel asymmetric collider design using advanced accelerator technologies to enable dark photon searches below 1 GeV with high luminosity, overcoming traditional low-energy collider challenges.

Contribution

It introduces a new collider configuration combining a positron storage ring and an electron ERL to achieve high luminosity below 1 GeV, leveraging recent accelerator innovations.

Findings

Achieves >10^{34} cm^{-2}s^{-1} luminosity at <1 GeV energy.

Utilizes nano-beam scheme, ERL, and magnetized beams for low-energy collider design.

Provides a specific example based on SuperKEK-B and Cornell parameters.

Abstract

Current searches for a dark photon in the mass range below 1 GeV require an electron-positron collider with a luminosity at the level of at least $10^{34}$ cm$^{-2}$s$^{-1}$. The challenge is that, at such low energies, the collider luminosity rapidly drops off due to increase in the beam sizes, strong mutual focusing of the colliding beams, and enhancement of collective effects. Using recent advances in accelerator technology such as the nano-beam scheme of SuperKEK-B, high-current Energy Recovery Linacs (ERL), and magnetized beams, we propose a new configuration of an electron-positron collider based on a positron storage ring and an electron ERL. It allows one to achieve a luminosity of $>10^{34}$ cm$^{-2}$s$^{-1}$ at the center of momentum energy of <1 GeV. We present general considerations and a specific example of such a facility using the parameters of the SuperKEK-B positron storage ring and Cornell ERL project.