Simulating neutrino echoes induced by secret neutrino interactions

TL;DR

This paper develops a Monte Carlo simulation framework to study how secret neutrino interactions with the cosmic background affect the timing and energy spectra of astrophysical neutrinos, aiding future BSM physics searches.

Contribution

It introduces a novel simulation method for modeling neutrino echoes from secret interactions, including multiple scatterings and resonance effects, beyond simple analytical estimates.

Findings

Simulation results match analytical predictions for low optical depths.

Framework can handle optically-thick cases with complex scattering.

Results inform detection strategies for current and future neutrino observatories.

Abstract

New neutrino interactions beyond the Standard Model (BSM) have been of much interest in not only particle physics but also cosmology and astroparticle physics. We numerically investigate the time delay distribution of astrophysical neutrinos that interact with the cosmic neutrino background. Using the Monte Carlo method, we develop a framework that enables us to simulate the time-dependent energy spectra of high-energy neutrinos that experience even multiple scatterings en route and to handle the sharp increase in the cross section at the resonance energy. As an example, we focus on the case of secret neutrino interactions with a scalar mediator. While we find the excellent agreement between analytical and simulation results for small optical depths, our simulations enable us to study even optically-thick cases that are not described by the simplest analytic estimates. Our simulations are used to understand effects of cosmological redshifts, neutrino spectra and flavors. The developments will be useful for probing BSM neutrino interactions with not only current neutrino detectors such as IceCube and Super-Kamiokande but also future neutrino detectors such as IceCube-Gen2 and Hyper-Kamiokande.