Constraining primordial black holes as dark matter at JUNO

TL;DR

This paper explores how the JUNO neutrino detector can constrain primordial black holes as dark matter by detecting neutrino signals from Hawking radiation, significantly improving current limits especially for lighter PBHs.

Contribution

It demonstrates the potential of JUNO to set new, tighter bounds on PBH dark matter fraction using neutrino detection, particularly via inverse beta decay channel.

Findings

JUNO can improve bounds on PBH dark matter fraction by a factor of 20 for 10^{15} g PBHs.

The inverse beta decay channel is most sensitive for detecting PBH Hawking radiation.

Constraints weaken for heavier PBHs with lower Hawking temperatures.

Abstract

As an attractive candidate for dark matter, the primordial black holes (PBHs) in the mass range ($10^{15} \sim 10^{16}$)$\mathrm{g}$ could be detected via their Hawking radiation, including neutrinos and antineutrinos of three flavors. In this paper, we investigate the possibility to constrain the PBH as dark matter by measuring (anti)neutrino signals at the large liquid-scintillator detector of Jiangmen Underground Neutrino Observatory (JUNO). Among six available detection channels, the inverse beta decay $\overline{\nu}^{}_e + p \to e^+ + n$ is shown to be most sensitive to the fraction $f^{}_{\rm PBH}$ of PBHs contributing to the dark matter abundance. Given the PBH mass $M^{}_{\rm PBH} = 10^{15}~{\rm g}$, we find that JUNO will be able to place an upper bound $f^{}_{\rm PBH} \lesssim 3\times 10^{-5}$, which is 20 times better than the current best limit $f^{}_{\rm PBH} \lesssim 6\times 10^{-4}$ from Super-Kamiokande. For heavier PBHs with a lower Hawking temperature, the (anti)neutrinos become less energetic, leading to a relatively weaker bound.