# Cosmic-ray transport from AMS-02 B/C data: benchmark models and interpretation

## TL;DR

This paper establishes new benchmark models for Galactic cosmic-ray propagation using AMS-02 B/C data, highlighting robust high-energy predictions and potential low-energy spectral features related to magnetic turbulence.

## Contribution

It introduces a comprehensive fitting procedure and the BIG model, combining minimal diffusion and convection-reacceleration scenarios for cosmic-ray transport analysis.

## Key findings

- Robust high-energy diffusion slope $\delta$ between 0.43 and 0.53
- Diffusion coefficient $K_{10}$ between 0.26 and 0.36 kpc$^2$/Myr at 10GV
- Confirmation of a high-energy spectral break around 10GV with $\Delta_h \\sim 0.2"

## Abstract

This article aims at establishing new benchmark scenarios for Galactic cosmic-ray propagation in the GV-TV rigidity range, based on fits to the AMS-02 B/C data with the USINE v3.5 propagation code. We employ a new fitting procedure, cautiously taking into account data systematic error correlations in different rigidity bins and considering Solar modulation potential and leading nuclear cross-section as nuisance parameters. We delineate specific low, intermediate, and high-rigidity ranges that can be related to both features in the data and peculiar microphysics mechanisms resulting in spectral breaks. We single out a scenario which yields excellent fits to the data and includes all the presumably relevant complexity, the BIG model. This model has two limiting regimes: (i) the SLIM model, a minimal diffusion-only setup, and (ii) the QUAINT model, a convection-reacceleration model where transport is tuned by non-relativistic effects. All models lead to robust predictions in the high-energy regime ($\gtrsim10$GV), i.e. independent of the propagation scenario: at $1\sigma$, the diffusion slope $\delta$ is $[0.43-0.53]$, whereas $K_{10}$, the diffusion coefficient at 10GV, is $[0.26-0.36]$kpc$^2$Myr$^{-1}$; we confirm the robustness of the high-energy break, with a typical value $\Delta_h\sim 0.2$. We also find a hint for a similar (reversed) feature at low rigidity around the B/C peak ($\sim 4$GV) which might be related to some effective damping scale in the magnetic turbulence.