Probing flavor changing neutrino interactions using neutrino beams from a muon storage ring

Abstract

We discuss the capabilities of a future neutrino factory based on intense neutrino beams from a muon storage ring to explore the nonstandard neutrino matter interactions, which are assumed to be subleading effects in the standard mass induced neutrino oscillations. The conjunction of these two mechanisms will magnify the fake $\mathrm{CP}$ violating effect in the presence of matter which is not coming from the $\mathrm{CP}$ phase in the neutrino mixing matrix. We show that such a fake $\mathrm{CP}$ violation can be observed in neutrino factory experiments by measuring the difference between the neutrino and antineutrino probabilities. In order to perform such a test, we consider three neutrino flavors, admitting the mixing parameters in the range consistent with the oscillation solution to the atmospheric and the solar neutrino problems, as well as with the constraints imposed by the reactor neutrino data. We show that with a 10 kt detector with 5 years of operation, a stored muon energy ${E}_{\ensuremath{\mu}}>~20$ GeV, $2\ifmmode\times\else\texttimes\fi{}{10}^{20}$ muon decays per year, and a base line $L\ensuremath{\sim}732$ km, such a neutrino facility can probe the nonstandard flavor changing neutrino interactions down to the level of ${(10}^{\ensuremath{-}3}$--${10}^{\ensuremath{-}2}{)G}_{F}$ in both ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{\ensuremath{\tau}}/{\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ and ${\ensuremath{\nu}}_{e}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{\ensuremath{\tau}}/{\overline{\ensuremath{\nu}}}_{e}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ modes.