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Bounds on the Coupling of the Majoron to Light Neutrinos from Supernova Cooling

Yasaman Farzan

TL;DR

<p>Bounded by the SN cooling constraint, this paper analyzes Majoron emission as a cooling channel to constrain neutrino–Majoron couplings. It develops in-medium neutrino propagators and a comprehensive set of three- and four-point Majoron processes, showing that energy loss is dominated by medium-allowed $\nu\nu \to J$-type interactions and that the strongest bound on $|g_{ee}|$ is $|g_{ee}| \lesssim 4\times 10^{-7}$ under plausible inner-core conditions; bounds on $|g_{\mu\mu}|$, $|g_{\tau\tau}|$, and $|g_{e\mu}|$, $|g_{e\tau}|$ lie roughly in the $10^{-7}$ to $10^{-6}$ range, with outer-core decays occasionally tightening the limits. Four-point interactions are shown to be negligible unless couplings are above $\sim 10^{-5}$, at which point Majoron trapping and core-density feedback become important, requiring a re-evaluation of the core evolution. The results refine previous SN bounds and illuminate how medium effects and process substructure determine the viable Majoron parameter space, with implications for supernova phenomenology and beyond-Standard-Model neutrino interactions.</p>

Abstract

We explore the role of Majoron ($J$) emission in the supernova cooling process, as a source of upper bound on neutrino-Majoron coupling. We show that the strongest upper bound on the coupling to $ν_e$ comes from the $ν_eν_e \to J $ process in the core of a supernova. We also find bounds on diagonal couplings of the Majoron to $ν_{μ(τ)}ν_{μ(τ)}$ and on off-diagonal $ν_e ν_{μ(τ)}$ couplings in various regions of the parameter space. We discuss the evaluation of the cross-section for four-particle interactions ($νν\to JJ$ and $νJ \to νJ$). We show that these are typically dominated by three-particle sub-processes and do not give new independent constraints.

Bounds on the Coupling of the Majoron to Light Neutrinos from Supernova Cooling

TL;DR

<p>Bounded by the SN cooling constraint, this paper analyzes Majoron emission as a cooling channel to constrain neutrino–Majoron couplings. It develops in-medium neutrino propagators and a comprehensive set of three- and four-point Majoron processes, showing that energy loss is dominated by medium-allowed -type interactions and that the strongest bound on is under plausible inner-core conditions; bounds on , , and , lie roughly in the to range, with outer-core decays occasionally tightening the limits. Four-point interactions are shown to be negligible unless couplings are above , at which point Majoron trapping and core-density feedback become important, requiring a re-evaluation of the core evolution. The results refine previous SN bounds and illuminate how medium effects and process substructure determine the viable Majoron parameter space, with implications for supernova phenomenology and beyond-Standard-Model neutrino interactions.</p>

Abstract

We explore the role of Majoron () emission in the supernova cooling process, as a source of upper bound on neutrino-Majoron coupling. We show that the strongest upper bound on the coupling to comes from the process in the core of a supernova. We also find bounds on diagonal couplings of the Majoron to and on off-diagonal couplings in various regions of the parameter space. We discuss the evaluation of the cross-section for four-particle interactions ( and ). We show that these are typically dominated by three-particle sub-processes and do not give new independent constraints.

Paper Structure

This paper contains 19 sections, 104 equations, 1 figure, 1 table.

Table of Contents

  1. Introduction
  2. Majoron interactions
  3. The propagators and the dispersion relation
  4. The relevant decays and interactions
  5. $\bar{\nu} \rightarrow \nu +J$ or $\nu \rightarrow \bar{\nu} +J$
  6. $\nu+ \nu \rightarrow J$ or $\bar{\nu} +\bar{\nu} \rightarrow J$
  7. The process $\nu+ \bar{\nu} \rightarrow J+J$
  8. The process $\nu+ \nu \rightarrow J+ J$ and $\bar{\nu}+\bar{\nu}\rightarrow J+ J$
  9. The processes $\nu +J \rightarrow \bar{\nu}$ or $\bar{\nu} +J \rightarrow \nu$:
  10. The Majoron decay, $J \rightarrow \nu +\nu$ or $J\rightarrow \bar{\nu}+ \bar{\nu}$
  11. The processes $\nu+ J \to \bar{\nu} +J$ and $\bar{\nu} +J\to \nu + J$
  12. The processes $\nu+J \rightarrow \nu +J$ and $\bar{\nu}+J \rightarrow \bar{\nu} +J$
  13. Supernova core without Majorons
  14. Bounds on coupling constants
  15. Bounds on $|g_{ee}|$
  16. ...and 4 more sections

Figures (1)

  • Figure :