Search for GeV-scale sterile neutrinos responsible for active neutrino oscillations and baryon asymmetry of the Universe

TL;DR

This paper proposes a new proton beam-dump experiment at CERN SPS to search for GeV-scale sterile neutrinos, which could explain neutrino oscillations, dark matter, and baryon asymmetry, and discusses its feasibility and potential to discover or rule out such particles.

Contribution

It introduces a novel experimental setup and feasibility study for detecting GeV-scale sterile neutrinos within the nuMSM framework, extending current search capabilities.

Findings

Feasibility of detecting sterile neutrinos with <2 GeV mass at CERN SPS.

Sensitivity sufficient to discover or exclude right-handed neutrinos below the Fermi scale.

Proposed experiment can test key predictions of the nuMSM model.

Abstract

Standard model of particle physics fails to explain neutrino oscillations, dark matter and baryon asymmetry of the Universe. All these problems can be solved with three sterile neutrinos added to the model. Quite remarkably, if sterile neutrino masses are well below the electroweak scale, this modification --- Neutrino Minimal Standard Model (nuMSM) --- can be tested experimentally. We discuss a new experiment on search for decays of GeV-scale sterile neutrinos, which in the framework of the nuMSM are responsible for the matter-antimatter asymmetry generation and for the active neutrino masses. If lighter than 2 GeV, these particles can be produced in decays of charm mesons generated by high energy protons in a target of a proton beam-dump experiment, and subsequently decay into light SM particles. In order to fully explore this sector of the nuMSM, the new experiment requires data obtained with at least 10^{20} incident protons on target (achievable at CERN SPS in the future), and a big volume detector constructed from a large amount of identical single modules, with a total sterile neutrino decay length of few kilometers. The preliminary feasibility study for the proposed experiment shows that it has sensitivity which may either lead to the discovery of new particles below the Fermi scale --- right-handed partners of neutrinos --- or rule out see-saw sterile neutrinos with masses below 2 GeV.