MiMeS: Misalignment mechanism solver

We introduce a C++ header-only library that is used to solve the axion equation of motion, MiMeS. MiMeS makes no assumptions regarding the cosmology and the mass of the axion, which allows the user to consider various cosmological scenarios and axion-like models. MiMeS also includes a convenient python interface that allows the library to be called without writing any code in C++, with minimal overhead. Program summary Program title: MiMeS CPC Library link to program files: https://doi.org/10.17632/8ttm4snpzj.1 Developer's repository link: https://github.com/dkaramit/MiMeS Programming language: C++ and python Licensing provisions: MIT license Nature of problem: Solving numerically the axion (or axion-like-particle) equation of motion, in order to determine the corresponding relic abundance. The library is designed to be quite general, and can be used to obtain the relic abundance in various cosmological scenarios, and axion-like-particle models. Solution method: Embedded Runge-Kutta for the numerical integration of the equation of motion. The user may choose between explicit and Rosenborck methods, or implement their own Butcher tableau. For the various interpolations, the library uses cubic splines. Additional comments including restrictions and unusual features: The derivative of the axion-angle initially is assumed vanish. This is hard-coded in the library, and there is no easy way for the user to change it. Furthermore, any additional contribution from decays or annihilation of plasma particles to the axion (or ALP) energy density is assumed to be subdominant. (C) 2022 Elsevier B.V. All rights reserved.