Ascertaining the spin for new resonances decaying into tau+ tau- at Hadron Colliders

TL;DR

This paper compares spin-0 and spin-2 hypotheses for a 125 GeV particle decaying into tau pairs at the LHC, using spin correlations and the TauSpinner algorithm to distinguish between them.

Contribution

It introduces a method to differentiate the spin of a new resonance decaying into tau pairs using simulated data and spin correlation analysis.

Findings

Demonstrates discrimination power between spin hypotheses

Uses TauSpinner to re-weight distributions for spin-2 hypothesis

Provides a framework for analyzing spin in tau decay channels

Abstract

Evidence of a new particle with mass ~125 GeV decaying into a pair of tau leptons at the Large Hadron Collider spurs interest in ascertaining its spin in this channel. Here we present a comparative study between spin-0 and spin-2 nature of this new particle, using spin correlations and decay product directions. The TauSpinner algorithm is used to re-weight distributions from qqbar -> gamma/Z -> tau+ tau- sample to simulate a spin-2 state exchange. The method is based on supplementing the Standard Model matrix elements with those arising from presence of a new interaction. Studies with simulated samples demonstrate the discrimination power between these spin hypotheses based on data collected at the Large Hadron Collider.