Bounds on Exotic Couplings from a New $ν$-Background

TL;DR

This paper proposes a novel diffuse neutrino background generated by quenched superradiance of rotating primordial black holes. By balancing boson-cloud growth with neutrino production, the authors compute the diffuse background (DQS$\nu$B) and propagate it to today through cosmological redshift, then derive lower bounds on neutrino–boson couplings from $\Delta N_{\rm eff}$ and Super-Kamiokande constraints. The approach uses parametric excitation for scalars and Schwinger-like production for vectors, with observed energies spanning a broad range due to early-universe PBH formation. The results provide a new probe of beyond-Standard-Model neutrino interactions and PBH dark matter scenarios, highlighting potential observables in future experiments.

Abstract

We propose a hitherto unexplored neutrino background emerging from the mechanism of quenched superradiance of rotating primordial black holes. The quenching of the phenomenon happens through fermionic production, in our case neutrino production, from the boson cloud formed due to superradiance. The couplings involved in these interactions are bounded from above through several studies. In this work we put lower bounds on such scalar and vector couplings.

Figures (2)

• Figure 1: The DQS$\nu$B due corresponding to the the benchmark parameters given in Tab. \ref{['bpscavec']}. The detected and predicted flux from various other neutrino sources have also been shown for comparison.
• Figure 2: (Left) Bounds of $g_v$ from the vector mediated DQS$\nu$B mechanism along with other existing universal bounds. The brown bounds depict the constrains from $\Delta N_{\mathrm{eff}}$ at recombination from neutrinos and the blue bounds depict the constrains from the Super-Kamiokande data. (Right) Bounds of $g_s$ from the scalar mediated DQS$\nu$B mechanism along with other universal bounds. The brown bounds depict the constrains from $\Delta N_{\mathrm{eff}}$ at recombination from neutrinos.