Long-range forces: atmospheric neutrino oscillation at a magnetized detector

Abstract

Among the combinations Le-Lμ, Le-Lτ and Lμ-Lτ any one can be gauged in anomaly free way with the standard model gauge group. The masses of thesegauge bosons can be so light that it can induce long-range forces on the Earth due to theelectrons in the Sun. This type of forces can be constrained significantlyfrom neutrino oscillation. As the sign of the potential is opposite for neutrinos and antineutrinos, a magnetized iron calorimeter detector (ICAL) would be able to produce strong constraint on it. We have made conservative studies of these long-range forces with atmospheric neutrinos at ICAL considering only the muons of charge current interactions.We find stringent bounds on the couplings αeμ,eτ ⪅ 1.65 × 10−53 at 3σ CL with an exposure of 1 Mton·yr if there is no such force. For nonzero input values of the couplings we find thatthe potential Veμ opposes and Veτ helps to discriminate the mass hierarchy.However, both potentials help significantly to discriminate the octant of θ23. The explanation of the anomaly in recent MINOS data (the difference of Δm322 for neutrinos and antineutrinos), using long-range force originated from the mixing of the gauge boson Z′ of Lμ-Lτ with the standard model gauge boson Z,can be tested at ICAL at more than 5σ CL. We have also discussed how to disentangle this from the solution with CPT violationusing the seasonal change of the distance between the Earth and the Sun.