Re-examining the Solar Axion Explanation for the XENON1T Excess

Understand

The XENON1T collaboration has observed an excess in electronic recoil events below $5~\mathrm{keV}$ over the known background, which could originate from beyond-the-Standard-Model physics.

• The solar axion is a well-motivated model that has been proposed to explain the excess, though it has tension with astrophysical observations.
• The axions traveled from the Sun can be absorbed by the electrons in the xenon atoms via the axion-electron coupling.
• Meanwhile, they can also scatter with the atoms through the inverse Primakoff process via the axion-photon coupling, which emits a photon and mimics the electronic recoil signals.