Weighing Wimps with Kinks at Colliders: Invisible Particle Mass Measurements from Endpoints

TL;DR

This paper introduces a method using endpoint kinks in transverse mass distributions to determine the masses of invisible particles and their parent particles at colliders, with potential application at the LHC.

Contribution

It demonstrates that the endpoint of certain transverse mass observables exhibits a kink at the true invisible particle mass, enabling mass measurements in collider experiments.

Findings

Endpoint kinks occur at the true invisible particle mass in most cases.

The method allows simultaneous determination of parent and invisible particle masses.

Prospects for applying this technique at the LHC are discussed.

Abstract

We consider the application of endpoint techniques to the problem of mass determination for new particles produced at a hadron collider, where these particles decay to an invisible particle of unknown mass and one or more visible particles of known mass. We also consider decays of these types for pair-produced particles and in each case consider situations both with and without initial state radiation. We prove that, in most (but not all) cases, the endpoint of an appropriate transverse mass observable, considered as a function of the unknown mass of the invisible particle, has a kink at the true value of the invisible particle mass. The co-ordinates of the kink yield the masses of the decaying particle and the invisible particle. We discuss the prospects for implementing this method at the LHC.