Search for Inelastic Boosted Dark Matter with the ICARUS Detector at the Gran Sasso Underground National Laboratory

TL;DR

This paper reports a search for inelastic boosted dark matter using the ICARUS detector, setting new limits on dark photon parameters based on zero observed events in a 0.13 kton-year exposure.

Contribution

First search for inelastic boosted dark matter with the ICARUS detector, establishing exclusion limits on dark photon parameters in this context.

Findings

Zero events observed after analysis

Set exclusion limits on dark photon mass and coupling

Demonstrated the detector's capability for dark matter searches

Abstract

We present the result of a search for inelastic boosted dark matter using the data corresponding to an exposure of 0.13 kton$\cdot$year, collected by the ICARUS T-600 detector during its 2012--2013 operational period at the INFN Gran Sasso Underground National Laboratory. The benchmark boosted dark matter model features a multi-particle dark sector with a U(1)$'$ gauge boson, the dark photon. The kinetic mixing of the dark photon with the Standard Model photon allows for a portal between the dark sector and the visible sector. The inelastic boosted dark matter interaction occurs when a dark matter particle inelastically scatters with an electron in the ICARUS detector, producing an outgoing, heavier dark sector state which subsequently decays back down to the dark matter particle, emitting a dark photon. The dark photon subsequently couples to a Standard Model photon through kinetic mixing. The Standard Model photon then converts to an electron-positron pair in the detector. This interaction process provides a distinct experimental signature which consists of a recoil electron from the primary interaction and an associated electron-positron pair from the secondary vertex. After analyzing 4,134 triggered events, the search results in zero observed events. Exclusion limits are set in the dark photon mass and coupling ($m_X, \epsilon$) parameter space for several selected optimal boosted dark matter mass sets.