Search for exotic neutrino interactions using solar neutrinos in XMASS-I

We have searched for exotic neutrino-electron interactions that could be produced by a neutrino millicharge, magnetic moment or dark photons using solar neutrinos in the XMASS-I. No significant signals have been observed and upper limit of these constant values are estimated as preliminary. For the neutrino millicharge search, $5.4\times10^{-11}$e for all flavors of neutrino is obtained. We also set individual flavors to be $7.3\times10^{-12}e$ for $\nu_e$, $1.1\times10^{-11}e$ for $\nu_{\mu}$, and $1.1\times10^{-11}e$ for $\nu_{\tau}$. These limits ate the most stringent yet obtained from direct measurements. For the neutrino magnetic moment search, $1.8\times10^{-10}\mu_{B}$ is obtained. In addition, we obtain upper limits for the coupling constant of dark photons and almost exclude the possibility to understand the muon $g-2$ anomaly by dark photons.