Prying Open the Dark Sector Window with SBND Off-Target Mode

TL;DR

This paper investigates how operating the SBND detector in off-target and beam-dump modes at Fermilab can significantly improve the sensitivity to various new physics phenomena beyond the Standard Model.

Contribution

It explores the physics potential of SBND in off-target configurations, demonstrating enhanced sensitivity to light dark matter, axion-like particles, and other new physics scenarios.

Findings

Off-target mode suppresses neutrino backgrounds, improving detection sensitivity.

Projected sensitivities extend to light dark matter and axion-like particles.

Beam-dump configurations significantly enhance new physics discovery potential.

Abstract

Accelerator-based neutrino experiments with high-intensity proton beams and advanced detector technologies provide a powerful and complementary approach to probing physics beyond the Standard Model. The MiniBooNE experiment at Fermilab pioneered a dedicated Booster Neutrino Beam (BNB) off-target (beam-dump) run, setting leading constraints on sub-GeV dark matter. In this work, we explore the physics opportunities enabled by operating the Short-Baseline Near Detector (SBND) at Fermilab in a future BNB off-target configuration, as well as in a dedicated beam-dump configuration. By redirecting the proton beam away from the nominal beryllium target, or by employing a dedicated beam-dump, neutrino-induced backgrounds are substantially suppressed, thereby enhancing SBND's sensitivity to many new physics scenarios. We demonstrate that such running modes significantly extend the reach for new physics. As representative examples, we present projected sensitivities to light dark matter, axion-like particles, heavy neutral leptons, and meson-portal scenarios.