Correction to: Eur. Phys. J. H (2023) 48:13 https://doi.org/10.1140/epjh/s13129-023-00061-4

In the original article, the last sentence of section 6 is incorrect: “The first measurements, published in September 1969, found a ratio of \(0.2\pm 0.2\), which was encouraging for supporters of the quark model”.

The correct sentence should read: “The first measurements, published in September 1970, found a ratio of \(0.2\pm 0.2\), which was encouraging for supporters of the quark model”. September 1970 is correct.

The original article has been corrected.