Effects of Anomalous Couplings on Spin Determination in Cascade Decays

TL;DR

This paper demonstrates that the existing methods for determining particle spins from decay spectra remain valid even when higher-dimensional operators are present, indicating robustness against certain beyond Standard Model effects.

Contribution

It shows analytically that dim-5 and dim-6 operators do not alter the structure of lepton and quark spectra used for spin determination in cascade decays.

Findings

Existing spin determination strategies are robust against higher-dimensional operators.

Higher-dimensional operators do not change the spectral structure used for spin analysis.

The analytical proof supports the applicability of current methods in extended models.

Abstract

Determining the spin of new particles is an important tool for discriminating models beyond the Standard Model. We show that in case of cascades of subsequent two body decays the existing strategy to extract the spin from lepton and quark spectra can be used without changes even if one allows for dim-5 and dim-6 operators which might be induced by physics just beyond the reach of LHC. We show analytically that these operators do not change the overall structure of these spectra.