Corrigendum to “Search for a common baryon source in high-multiplicity pp collisions at the LHC” [Phys. Lett. B 811 (2020) 135849]

In the original paper [1], the relative distance [Formula presented] pairs composed of one primary and one secondary (i.e. coming from resonance decay) proton was not calculated correctly. Specifically, Eq. (5) in the original paper for the scenario in which one proton (proton 1) is primary and the other (proton 2) originates from a resonance decay should read [Formula presented], but it was implemented in the code used to extract the source core radius with a minus sign, namely [Formula presented]. The mistake was not present in the code used for the p–Λ results. The error leads to a reduction of the final total source size which hence required eventually a larger source core size to describe the measured [Formula presented] correlations, compared with the published p–Λ results. The plot in the right panel of Fig. 1 replaces Fig. 5 in the original manuscript. The corrected numerical values are also available via HEPData [2]. The fitting procedure and the modelling of the resonances used for the updated results are the same as in the original paper, described respectively in Sec. 3 and Sec. 4 [1]. The net effect of the correction is a systematic shift, across all [Formula presented] value for the p–p system of ∼ 0.09 fm. Considering the statistical and systematic uncertainties, the number of standard deviations ([Formula presented]. This value was obtained using the NLO13 p–Λ interaction from Ref. [3] for direct comparison with the results in the original manuscript. However, more recent studies on the source and the p–Λ interaction [4,5] have shown that the NLO parameterization [1,3] overestimates the spin-averaged scattering length by 10–15%. This implies that the extracted [Formula presented] for p–Λ (red points in Fig. 1) are biased towards larger radii. To address this, the p–Λ correlation functions in each [Formula presented] bin have been re-fitted with an Usmani potential [6], fine-tuned to the eight best solutions listed in Table 1 of [5]. The best compatibility ([Formula presented]) between the p–p and p–Λ source sizes is achieved using point iv) from Table 1 in [5], which has scattering length (f) in the singlet (s) and triplet (t) channel of [Formula presented] scaling (red points) is plotted in the right panel of Fig. 2 and compared to the p–p results (blue band). These findings confirm the original message of the paper about the observation of a common [Formula presented] scaling of the [Formula presented] TeV. Implications for other femtoscopic analyses In the original paper, the [Formula presented] values, extracted from the p–p correlation functions, were parameterized using the function [Formula presented] and used in several subsequent femtoscopic analyses [9–17]. For these analyses, the source distribution was determined by calculating the average [Formula presented] of the analysed pairs, evaluating the corresponding [Formula presented] (Eq. (1)), and then incorporating the pair-specific source broadening caused by resonance decays. This approach, outlined in Eqs. 4 and 5 of [1], typically results in a source distribution that resembles a Gaussian with an additional tail attributed to resonances. In most cases, the source function can be approximated by an effective Gaussian described by its width [Formula presented]. This parameter is then used to extract the properties of the mutual strong interaction between the species under study from the measured two-particle correlation function. In particular, the published results [9–17] used the [Formula presented] extracted from p–p correlations [1] to fix the core of the emission source, from which the corresponding [Formula presented] has been estimated. The procedure to include the resonances has been properly implemented in all analyses [9–17], apart from the p–p correlation [1]. Since the effective Gaussian source size [Formula presented], its modification affects all subsequent analyses [9–17]. In this work, this modification is investigated and quantified. The values of the [Formula presented] for p–p pairs reported in the right panel of Fig. 1 are shown in Fig. 2, without the p–Λ results. The blue band shows the parameterization by Eq. (1) with the parameter values given in Table 1. The input argument [Formula presented] has units of [Figure presented], while the output [Formula presented] is in fm. The old and updated values of the a, b and c parameters are in agreement within the reported limits. In Table 2 we report the updated values for the [Formula presented] and the effective single-Gaussian source sizes used in the different femtoscopic analyses to evaluate the theoretical correlation function employed to model the data. In brackets we list the values obtained using the [Formula presented] extracted in the original paper [1]. For most systems both the [Formula presented] have been affected, nevertheless for the N–N source within the p–d system [15] the [Formula presented] remains unchanged. This is because the wrong code has been used both to evaluate.