Constraining primordial black holes as dark matter at JUNO
  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.
