It has been recently suggested that the vacuum magnetic dichroism observed by the PVLAS experiment could be explained by the pair production of a new light, m ~0.1 eV, millicharged, q ~ 3 10^{ -6} e, fermions. In addition, it has been pointed out that millicharged particles with q > 10^{ -9} e appear naturally in models based on the string theory. We show that low energy reactor neutrino experiments provide a sensitive probe of millicharged particles. Considering, as an example, recent results of the TEXONO experiment searching for neutrino magnetic moment, a new upper bound q < 10^{ -5} e for the mass region m < 1 keV is derived. These results enhance motivations for a more sensitive search for such particles in near future experiments. Furthemore, a direct experimental limit on the electric charge of the electron antineutrino q < 3.7 10^{ -12} e is obtained.
Categories: hep-ph