Constraints on neutrino-Majoron couplings using SN1987A data

Abstract

Neutrino decay to a lighter neutrino and a massless or almost massless (pseudo)scalar Goldstone boson remains of wide interest, as in the search for ultralight dark matter or for neutrinoless double beta-decay, and for its implications in astrophysics and cosmology. Neutrino interactions with Majorons can affect the dynamics of supernovae and impact the emitted neutrino flux. Using a three-neutrino framework and detailed supernova simulations, we perform the first likelihood analysis of the 24 neutrino events from SN1987A, including nonradiative decay in matter to a massless (pseudo)scalar boson like a Majoron. Focusing on the induced spectral distortions, we present bounds on the neutrino-Majoron couplings, as a function of the lightest neutrino mass, that are either complementary or competitive with current ones.

Figures (3)

• Figure 1: Constraints on the neutrino-Majoron coupling in the $g_{11}-m_1$ plane from our SN1987A analysis considering normal ordering at 68% CL (blue), compared with constraints from the Majoron luminosity argument (red) as per Ref. Kachelriess:2000qc and the most stringent limits from $0\nu\beta\beta$ decay (yellow solid line) Kharusi:2021jez. The different red-shaded areas are obtained by requiring the limit from Ref. Kachelriess:2000qc on $g_{ee}$ (red solid line), $g_{\mu\mu}$ (red dotted line), and $g_{\tau\tau}$ (red dashed line). The current limit from the KATRIN experiment on the absolute neutrino mass is also shown Katrin:2024tvg.
• Figure 2: Constraints at 90% CL on the $g_{ee}$ neutrino-Majoron coupling as a function of the lightest neutrino mass obtained from our $3 \nu$ likelihood analysis for SN1987A events in normal (blue solid line) or inverted (blue dashed line) ordering. The red-shaded area indicates constraints from the Majoron luminosity argument Kachelriess:2000qc. Note that this limit assumes only one flavor at a time. Additionally, we show limits from $0\nu\beta\beta$ decay (from more stringent to less): EXO-200 Kharusi:2021jez (yellow dotted line), NEMO-3 NEMO-3:2015jgm (green dotted line), and CUPID-$0$CUPID-0:2022yws (pink dotted line). For each bound, the two dashed vertical lines connected by an arrow show how each bound varies when implementing the uncertainty from the nuclear matrix elements.
• Figure 3: Constraints at 90% CL on $\sum_\beta g_{\alpha\beta}^2$ for $\alpha = e$ (blue solid line), $\mu$ (red dotted line), and $\tau$ (yellow dashed line) obtained from our SN1987A analysis in normal (upper) and inverted ordering (lower figure). As a reference, limits obtained from pion decay PIENU:2021clt (gray solid line), kaon decay (black solid line), $\mu$ decay (black dotted line), and $\tau$ decay (black dashed line) Lessa:2007up.