Hunting up low-mass bosons from the Sun using HPGe detector

TL;DR

This paper reports on an experiment searching for keV-mass bosons emitted from the Sun using a high-purity germanium detector, setting new constraints on their couplings to electrons and nucleons, surpassing previous limits.

Contribution

It introduces a novel solar-based search for low-mass bosons via the photoelectric/Compton effect in HPGe detectors, providing stronger constraints on their couplings than prior methods.

Findings

Stronger limits on scalar-electron coupling for masses above 25 keV.

Enhanced constraints on Yukawa interactions beyond Casimir force measurements.

Improved bounds on boson emission from the Sun.

Abstract

In this experiment we aim to look for keV-mass bosons emitted from the Sun, by looking at a process analogous to the photoelectric/Compton effect inside the HPGe detector. Their coupling to both electrons and nucleons is assumed. For masses above 25 keV, the mass dependence of our limit on the scalar-electron coupling reveals a constraint which proves stronger than that obtained recently and based on the very good agreement between the measured and predicted solar neutrino flux from the ^{8}B reaction. On the other hand, the mass dependence of our limit on the scalar-proton/electron coupling together entails a limit on a possible Yukawa addition to the gravitational inverse square low. Such a constraint on the Yukawa interactions proves much stronger than that derived from the latest AFM Casimir force measurement.