This work reports femtoscopic correlations of p$-$p ($\bar{ \rm p}-\bar{ \rm p}$) and p$-$d ($\bar{ \rm p}-\bar{ \rm d}$) pairs measured in Pb$-$Pb collisions at center-of-mass energy per nucleon $\sqrt{ s_{ \rm NN}}$ = 5.02 TeV in the ALICE Collaboration. A fit to the measured proton-proton correlation functions allows one to extract the dependence of the nucleon femtoscopic radius of the particle-emitting source on the pair transverse mass ($m_\text{ T}$) and on the average charge particle multiplicity $\langle\text{ dN}_\text{ ch}/\text{ d}\eta\rangle^{ 1/3}$ for three centrality intervals (0$-$10$\%$, 10$-$30$\%$, 30$-$50$\%$). In both cases, the expected power-law and linear scalings are observed, respectively. The measured p$-$d correlations can be described by both two- and three-body calculations, indicating that the femtoscopy observable is not sensitive to the short-distance features of the dynamics of the p$-$(p$-$n) system, due to the large inter-particle distances in Pb$-$Pb collisions at the LHC. Indeed, in this study, the minimum measured femtoscopic source sizes for protons and deuterons have a minimum value at $2.73^{ +0.05}_{ -0.05}$ and $3.10^{ +1.04}_{ -0.86}$ fm, respectively, for the 30$-$50$\%$ centrality collisions. Moreover, the $m_{ \rm{ T}}$-scaling obtained for the p$-$p and p$-$d systems is compatible within 1$\sigma$ of the uncertainties. These findings provide new input for fundamental studies on the production of light (anti)nuclei under extreme conditions.
Categories: nucl-ex hep-ex