Measurement of the Spin of the Omega^- Hyperon at BABAR

TL;DR

This paper measures the spin of the Omega^- hyperon using BABAR data, providing evidence that supports a spin of 3/2 under certain assumptions, with some ambiguity if the initial particle's spin is different.

Contribution

The study presents the first measurement of the Omega^- hyperon spin using e+e- collision data, confirming its spin as 3/2 under specific assumptions.

Findings

Omega^- spin is consistent with 3/2 based on angular distributions.

Data from Xi_c^0 decay supports Omega^- spin 3/2 hypothesis.

Alternative initial particle spin assumptions leave some ambiguity.

Abstract

A measurement of the spin of the Omega^- hyperon produced through the exclusive process Xi_c^0 --> Omega^- K^+ is presented using a total integrated luminosity of 116 fb^-1 recorded with the BABAR detector at the e^+ e^- asymmetric-energy B-Factory at SLAC. Under the assumption that the Xi_c^0 has spin 1/2, the angular distribution of the Lambda from Omega^- --> Lambda K^- decay is inconsistent with all half-integer Omega^- spin values other than 3/2. Lower statistics data for the process Omega_c^0 --> Omega^- pi^+ from a 230 fb^-1 sample are also found to be consistent with Omega^- spin 3/2. If the Xi_c^0 spin were 3/2, an Omega^- spin of 5/2 cannot be excluded.