Constraining primordial black holes as dark matter at JUNO

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.