Kira 1.2 Release Notes

TL;DR

Kira 1.2 enhances Feynman integral reduction by providing a faster equation generator, a flexible seed notation, and multiple predefined integral orderings, all within an updated build system that supports Meson. It adds an interface for solving user-defined linear systems, sectorwise forward elimination, algebraic reconstruction, improved symmetry handling, and the ability to merge reduction databases, collectively improving runtime and scalability. The release also offers practical guidance and best practices for topology definition, integral selection, seed strategies, and parallel reductions, alongside improved support for cut propagators and exporting reduction rules. Overall, Kira 1.2 strengthens robustness, flexibility, and efficiency for large-scale Laporta-based reductions in multi-loop calculations.

Abstract

We present the Feynman integral reduction program Kira 1.2 and describe its new features and other changes w.r.t. the previous versions. The main new features include a much faster equation generator, more flexible seed specification options, several predefined integral orderings, the reduction of systems of user-provided equations and a new technique to simplify coefficients by sampling variables over integers. Furthermore, we provide a collection of recommendations on how to use the program efficiently. This version has overall improvements in runtime for all reduction tasks compared to the previous versions of Kira.