Constraining visible neutrino decay at KamLAND and JUNO

Abstract

We study visible neutrino decay at the reactor neutrino experiments KamLAND and, JUNO. Assuming the Majoron model of neutrino decay, we obtain constraints on the couplings between Majoron and neutrino as well as on the lifetime/mass of the most massive neutrino state i.e., $$\tau _{3} / m_{3}$$ τ 3 / m 3 or $$\tau _{2} / m_{2}$$ τ 2 / m 2 , respectively, for the normal or the inverted mass orderings. We obtain the constraints on the lifetime $$\tau _{2} / m_{2} \ge 1.4 \times 10^{-9}~{\mathrm{s/eV}}$$ τ 2 / m 2 ≥ 1.4 × 10 - 9 s / eV in the inverted mass ordering for both KamLAND and JUNO at 90% CL. In the normal ordering in which the bound can be obtained for JUNO only, the constraint is milder than the inverted ordering case, $$\tau _{3} / m_{3} \ge 1.0 \times 10^{-10}$$ τ 3 / m 3 ≥ 1.0 × 10 - 10 s/eV at 90% CL. We find that the dependence of lightest neutrino mass ($$=m_{{{\mathrm{lightest}}}}$$ = m lightest ), $$m_1 (m_3)$$ m 1 ( m 3 ) for the normal (inverted) mass ordering, on the constraints for the different types of couplings (scalar or pseudo-scalar) is rather strong, but the $$m_{{{\mathrm{lightest}}}}$$ m lightest dependence on the lifetime/mass bound is only modest.

Neutrino oscillation phenomenology in the standard model and beyond

“…For different studies on visible neutrino decay at current or future experiments, we refer to Refs. [300][301][302][303][304][305][306].…”

Invisible neutrino decay: first vs second oscillation maximum

“…In ref. [62], the authors discuss the visible neutrino decay for reactor experiments KAMLAND and JUNO. For visible decay of the astrophysical neutrinos at IceCUBE, see ref.…”

Sensitivity of Next-Generation Neutrino Detectors to the Observation of Earth Matter Effects on Supernova Neutrinos in the Framework of Invisible Neutrino Decay

“…[27] found that DUNE will have a sensitivity of τ 3 /m 3 ≥ 4.27 × 10 −11 s/eV at 90% C.L.. Studies regarding visible neutrino decay, such as those considered in Ref. [28] constraint in the inverted ordering for both KamLAND and JUNO the lifetime of τ 2 /m 2 ≥ 1.4 × 10 −9 s/eV at 90% C.L. and in the normal mass ordering for JUNO τ 3 /m 3 ≥ 1.0 × 10 −10 s/eV at 90% C.L..…”

“…In the case of active neutrinos, lifetime bounds can be quite different depending on the neutrino mass ordering, if it is normal or inverted, see e.g. [28].…”

“…The best fit value for the mixing angle θ 23 lies in the second octant, with the first octant solution still allowed at ∼ 2.4σ [14]. These and other open questions such as the Dirac or Majorana nature [17,18,19,20,21,22,23], the absolute neutrino mass scale [24], the neutrino lifetime [25,26,27,28,29,30,31] are the primary goal of the current and future neutrino experiments.…”