Probing the Higgs Portal at the Fermilab Short-Baseline Neutrino Experiments

TL;DR

The paper evaluates the potential of Fermilab's Short-Baseline Neutrino experiments to detect light dark scalars via the Higgs portal, highlighting their sensitivity and proposing search strategies for these hidden particles.

Contribution

It provides a detailed analysis of the SBN experiments' capability to probe dark scalars, including production mechanisms, background mitigation, and sensitivity estimates for different detector configurations.

Findings

SBND has the best sensitivity with Booster beam.

ICARUS provides strong limits on off-axis production from NuMI.

Experiments can test dark scalars in the 50-350 MeV mass range.

Abstract

The Fermilab Short-Baseline Neutrino (SBN) experiments, MicroBooNE, ICARUS, and SBND, are expected to have significant sensitivity to light weakly coupled hidden sector particles. Here we study the capability of the SBN experiments to probe dark scalars interacting through the Higgs portal. We investigate production of dark scalars using both the Fermilab Booster 8 GeV and NuMI 120 GeV proton beams, simulating kaons decaying to dark scalars and taking into account the beamline geometry. We also investigate strategies to mitigate backgrounds from beam-related neutrino scattering events. We find that SBND, with its comparatively short ${\cal O}(100\ {\rm m})$ baseline, will have the best sensitivity to scalars produced with Booster, while ICARUS, with its large detector volume, will provide the best limits on off-axis dark scalar production from NuMI. The SBN experiments can provide leading tests of dark scalars with masses in the 50 - 350 MeV range in the near term. Our results motivate dedicated experimental searches for dark scalars and other long-lived hidden sector states at these experiments.