BSFfast: Fast Computation of Bound-State Effects in Early Universe Annihilation
Published:Dec 29, 2025 19:14
•1 min read
•ArXiv
Analysis
This paper introduces BSFfast, a tool designed to efficiently calculate the impact of bound-state formation (BSF) on the annihilation of new physics particles in the early universe. The significance lies in the computational expense of accurately modeling BSF, especially when considering excited bound states and radiative transitions. BSFfast addresses this by providing precomputed, tabulated effective cross sections, enabling faster simulations and parameter scans, which are crucial for exploring dark matter models and other cosmological scenarios. The availability of the code on GitHub further enhances its utility and accessibility.
Key Takeaways
- •BSFfast is a tool for rapidly computing bound-state effects on annihilation in the early universe.
- •It provides precomputed, tabulated effective cross sections, making it computationally efficient.
- •The tool supports a wide range of models, including those with excited bound states and radiative transitions.
- •It is designed for use in Boltzmann solvers and parameter scans.
- •The code is publicly available on GitHub.
Reference
“BSFfast provides precomputed, tabulated effective BSF cross sections for a wide class of phenomenologically relevant models, including highly excited bound states and, where applicable, the full network of radiative bound-to-bound transitions.”