Rotation-invariant relations in vector meson decays into fermion pairs

TL;DR

This paper generalizes the Lam-Tung identity, revealing a frame-independent relation in vector meson decays into fermions, linked to the polarization state of the originating photon, with implications for understanding decay dynamics.

Contribution

It introduces a universal, frame-independent relation among decay parameters, extending the Lam-Tung identity beyond Drell-Yan processes to all vector meson decays.

Findings

Derived a generalized, frame-independent decay relation.

Connected decay parameters to the polarization state of the photon.

Demonstrated the relation's applicability to various vector meson decays.

Abstract

The rotational properties of angular momentum eigenstates imply the existence of a frame-independent relation among the parameters of the decay distribution of vector mesons into fermions. This relation is a generalization of the Lam-Tung identity, a result specific to Drell-Yan production in perturbative QCD, here shown to be equivalent to the dynamical condition that the dilepton always originates from a transversely polarized photon.