Kinematic Cusps: Determining the Missing Particle Mass at Colliders

TL;DR

This paper introduces a method using kinematic cusp structures in decay distributions to accurately measure the mass of missing particles, such as dark matter candidates, at colliders, aiding new physics searches.

Contribution

It presents a novel technique leveraging kinematic cusps in invariant mass and angular distributions to determine missing particle and intermediate particle masses.

Findings

Cusps persist under realistic detector simulations.

Method effectively measures missing particle mass.

Applicable to collider searches for new physics.

Abstract

In many extensions of the SM, neutral massive stable particles (dark matter candidates) are produced at colliders in pairs due to an exact symmetry called a "parity". These particles escape detection, rendering their mass measurement difficult. In the pair production of such particles via a specific ("antler") decay topology, kinematic cusp structures are present in the invariant mass and angular distributions of the observable particles. Together with the end-points, such cusps can be used to measure the missing particle mass and the intermediate particle mass in the decay chain. Our simulation of a benchmark scenario in a Z' supersymmetric model shows that the cusp feature survives under the consideration of detector simulation and the standard model backgrounds. This technique for determining missing particle masses should be invaluable in the search for new physics at the LHC and future lepton colliders.