Type-I Error or Mass Bias ? An Investigation on the Omega_b Discovery

TL;DR

This paper critically examines the Omega_b particle discovery claims by D0 and CDF, revealing overestimated significance in D0's results and exploring potential causes for discrepancies through pseudoexperiments.

Contribution

It reevaluates the statistical significance of the D0 Omega_b signal and investigates the source of the discrepancy with CDF results using a pseudoexperiment approach.

Findings

D0's significance was overestimated in original analysis

Discrepancies between D0 and CDF likely due to statistical or systematic effects

Pseudoexperiments suggest the most probable cause of the differences

Abstract

The D0 and CDF collaborations recently published two independent analyses that both claim to represent the observation of the Omega_b particle, a baryon made up by a (bss) quark combination. Both signals are estimated to exceed the statistical significance of five standard deviations; however, the mass measurements derived from the candidates differ by over six standard deviations, accounting for estimated systematics. Measured rates also appear to differ, although they remain compatible within the large uncertainties. In this paper the author recomputes the significance of the D0 result, showing that it was considerably overestimated in the original publication; he then investigates with a pseudoexperiment-based approach which, among different hypotheses, appears the most likely cause of the observed discrepancy between the D0 and CDF signals.