Resolve transport parameters for young-Sun SEPs

Determine the young-Sun parallel mean free path, cross-field leakage, and flare-particle loss-cone escape fraction needed to replace the one-dimensional SEP transport estimates with a quantitatively reliable comparison between impulsive and CME-driven particle fluences at 1 AU.

Background

The paper estimates SEP decay and fluence using a one-dimensional, field-aligned diffusion model with assumed transport parameters. The young-Sun turbulence spectrum is unmeasured, and the escape fraction of flare-accelerated particles from the enlarged magnetic bottle is represented by a scaling estimate.

These quantities control the claimed dominance of the gradual CME-shock channel over the impulsive flare channel. A focused-transport calculation using young-Sun magnetic-field and turbulence conditions, coupled to a global heliospheric model, is needed to establish the fluence ratio.

References

The main uncertainties are $\lambda_\parallel$, because the young-Sun turbulence spectrum is unmeasured, and $f_{\rm esc}$, which needs a proper loss-cone and mirror calculation.

— Coronal Mass Ejections from the Young Sun: Deceleration-Powered Solar Energetic Particles as a Self-Extinguishing Forcing of the Early Earth  (2610.08758 - Panasenco, 6 Oct 2026) in Section 8, final paragraph before “From channel asymmetry to the fixation rate”