Mono-X signal and two component dark matter: new distinction criteria

TL;DR

This paper explores how to distinguish two-component dark matter signals at colliders, especially in mono-X events, by analyzing missing energy distributions and statistical significance plots, with a focus on electron-positron colliders.

Contribution

It introduces a novel criterion based on bin-wise significance versus missing energy to identify double peaks indicative of two dark matter components.

Findings

Double-peaking in missing energy can signal two dark matter components.

The significance plot against missing energy effectively reveals double peaks.

Criteria for identifying two-component dark matter signals are numerically demonstrated.

Abstract

The identification and isolation of two WIMP dark matter (DM) components at colliders is of wide interest on the one hand but extremely challenging on the other, especially when the dominant signal of both DM components is of the mono-X type ($X=\gamma, Z, H$). After emphasizing that an $e^+e^-$ collider is more suitable for this goal, we first identify the theoretical principles that govern the occurrence of two peaks in missing energy (ME) distribution, in a double-DM scenario. We then identify a variable that rather spectacularly elicits the double-peaking behaviour, namely, the plot of bin-wise statistical significance ($S/\sqrt{B}$) against ME. Using Gaussian fits of the histograms, we apply a set of criteria developed by us, to illustrate the above points numerically for suitable benchmarks.