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Recent cosmic-ray measurements are challenging our models of propagation inthe Galaxy. A good characterization of the secondary cosmic rays (B, Be, Li andsub-iron species) is crucial to constrain these models and exploit theprecision of modern CR experiments. In this work, a Markov chain Monte Carloanalysis has been implemented to fit the experimental flux ratios between B, Beand Li and their flux ratios to the primary nuclei C and O. We have fitted thedata using two different parametrizations for the spallation cross sections.The uncertainties in the evaluation of the spectra of these secondary cosmicrays, due to spallation cross sections, have been considered by introducingscale factors as nuisance parameters. We have also tested two differentformulations for the diffusion coefficient, which differ in the origin of thehigh energy hardening of cosmic rays. Additionally, two different approachesare used to scale the cross sections, one based on a combined analysis of allthe species ("combined" analysis) and the other reproducing the high energyspectra of the secondary-to-secondary flux ratios of Be/B, Li/B, Li/Be("scaled" analysis). This allows us to make a better comparison between thepropagation parameters inferred from the cross sections parametrizations testedin this work. This novel analysis has been successfully implemented using thenumerical code DRAGON2 to reproduce the cosmic-ray nuclei data up to $Z=14$from the AMS-02 experiment. It is found that the ratios of Li favor a harderspectral index of the diffusion coefficient, but compatible with the otherratios inside the observed $2\sigma$ uncertainties. In addition, it is shownthat, including these scale factors, the secondary-to-primary flux ratios canbe simultaneously reproduced.

Markov chain Monte Carlo analyses of the flux ratios of B, Be and Li with the DRAGON2 code