The Cosmic Ray Antiproton Spectrum and a Limit on the Antiproton Lifetime

TL;DR

This paper compares cosmic ray antiproton measurements with models to understand their origin and sets a new lower limit on the antiproton lifetime, highlighting the importance of heliospheric effects.

Contribution

It introduces an updated model combining Galactic production, propagation, and heliospheric modulation to match observations and derives a new lower limit on antiproton lifetime.

Findings

Model agrees with observed pbar/p ratio

Sets a lower limit on antiproton lifetime >1.7 Myr

Highlights importance of heliospheric corrections

Abstract

Measurements of the cosmic ray pbar/p ratio are compared to predictions from an inhomogeneous leaky box model of Galactic secondary pbar production combined with an updated heliospheric model that modulates the predicted fluxes measured at the Earth. The heliospheric corrections are crucial for understanding the low-energy part of the spectrum. The pbar production- propagation-modulation model agrees with observations. Adding a finite pbar lifetime to the model, we obtain the limit tau(pbar) > 1.7 Myr (90% C.L.). Restrictions on heliospheric properties and the cutoff of low-energy interstellar cosmic rays are discussed.