Minimal physical constraints on the angular distributions of two-body boson decays

TL;DR

This paper establishes fundamental physical constraints on the angular distributions of two-body boson decays, aiding model-independent spin determination and experimental analysis.

Contribution

It defines the minimal physical constraints on angular distributions, enabling model-independent discrimination of boson spin hypotheses, especially for J=0 versus J=2 cases.

Findings

Defines the physical parameter domain for decay angular distributions

Provides criteria for model-independent spin discrimination

Analyzes the J=2 decay distribution for experimental applications

Abstract

The angular distribution of the two-body decay of a boson of unknown properties is strongly constrained by angular momentum conservation and rotation invariance, as well as by the nature of the detected decay particles and of the colliding ones. Knowing the border between the "physical" and "unphysical" parameter domains defined by these "minimal constraints" (excluding specific hypotheses on what is still subject of measurement) is a useful ingredient in the experimental determinations of angular distributions and can provide model-independent criteria for spin characterizations. In particular, analysing the angular decay distribution with the general parametrization for the J = 2 case can provide a model-independent discrimination between the J = 0 and J = 2 hypotheses for a particle produced by two real gluons and decaying into two real photons.