A Speculative Benchmark for the AMS-02 Electron and Positron Spectra from a Time-Symmetric Transport Hypothesis

TL;DR

This paper explores a speculative time-symmetric transport hypothesis to interpret AMS-02 electron and positron spectra, introducing a minimal phenomenological model that isolates spectral features without complex spatial effects.

Contribution

It proposes a novel time-symmetric framework for cosmic ray propagation, emphasizing the spectral morphology and a reduced effective exposure of the advanced component.

Findings

Spectral morphology helps identify preferred parameter regions.

A benchmark with dominant advanced component and reduced exposure fits AMS-02 data.

The model captures key spectral features without spatial diffusion or solar modulation.

Abstract

We revisit the time-symmetric interpretation of antiparticles and explore whether it can be connected, as a speculative benchmark, to the distinct spectral structures observed in the AMS-02 electron and positron data. Rather than modifying the local radiative loss law, we adopt the standard high-energy energy-loss form for Galactic leptons, $b(E)=b_0E^2$, and introduce the time-symmetric hypothesis at the level of the effective propagation response. In this framework, the electron sector is treated as purely retarded, while the positron sector is modeled as an effective admixture of retarded and advanced-associated components. We perform a systematic 2D scan of the parameter space governing the macroscopic admixture fraction and the exposure reduction, and demonstrate that while the characteristic peak position is degenerate, the spectral morphology, especially the breadth of the turnover region, helps identify physically preferred benchmark regions. Based on this, we adopt a representative, order-of-magnitude benchmark, in which the advanced-associated component dominates the effective admixture but experiences a ten-fold reduction in effective radiative exposure, to dissect the underlying spectral components and verify the results against AMS-02 data. While omitting complex spatial diffusion and solar modulation, this minimal phenomenological framework naturally captures the widely separated energy scales of the lepton spectra, explicitly isolating the reduced effective radiative exposure of the advanced branch as a postulated ingredient requiring deeper theoretical justification.