Missing Momentum Reconstruction and Spin Measurements at Hadron Colliders

TL;DR

This paper introduces new methods for reconstructing invisible particle momenta and determining particle spins at hadron colliders, enhancing analysis of new physics scenarios like SUSY and UED.

Contribution

It develops techniques to reconstruct momenta using mass-shell constraints and determines spins from decay chain kinematics, applicable to particles initiating decay chains.

Findings

Effective momentum reconstruction using mass-shell constraints.

Methods to determine particle spins from decay kinematics.

Applicable to SUSY and UED models.

Abstract

We study methods for reconstructing the momenta of invisible particles in cascade decay chains at hadron colliders. We focus on scenarios, such as SUSY and UED, in which new physics particles are pair produced. Their subsequent decays lead to two decay chains ending with neutral stable particles escaping detection. Assuming that the masses of the decaying particles are already measured, we obtain the momenta by imposing the mass-shell constraints. Using this information, we develop techniques of determining spins of particles in theories beyond the standard model. Unlike the methods relying on Lorentz invariant variables, this method can be used to determine the spin of the particle which initiates the decay chain. We present two complementary ways of applying our method by using more inclusive variables relying on kinematic information from one decay chain, as well as constructing correlation variables based on the kinematics of both decay chains in the same event.