On the Particle Data Group evaluation of Psi' and chi_c Branching Ratios

TL;DR

This paper introduces a new method for evaluating the branching ratios of $A8'(2S)$ and $A8_c(1P)$ particles, addressing correlations and outdated measurements that affect current data accuracy.

Contribution

It presents a novel evaluation approach that reduces correlation biases and updates older measurements for more accurate branching ratio estimates.

Findings

New evaluation method reduces correlation biases.

Updated measurements significantly alter branching ratio estimates.

Identifies discrepancies in current Particle Data Group evaluations.

Abstract

I propose a new evaluation of $\psi'(2S)$ and $\chi_c(1P)$ branching ratios which avoids the correlations affecting the current Particle Data Group evaluation. These correlations explain the apparent technique-dependent discrepancies between the available determinations of the ${\cal B}(\chi_c(1P)\to p\bar p)$ and $\Gamma(\chi_c(1P)\to \gamma\gamma)$ under the hypotesis that the current values of the $\psi'(2S)\to\chi_c(1P)\gamma$ branching ratios are overestimated. In the process I also noticed that Particle Data Group has not restated many of the older measurements, when necessary, for the new value of ${\cal B}(J/\psi\to l^+l^-)$, which significantly affects the evaluation of some relevant $\psi'(2S)$ and $\chi_c(1P)$ exclusive branching ratios.