# Reduction of Couplings and its application in Particle Physics

## TL;DR

This paper discusses the reduction of couplings in renormalizable theories, especially in particle physics, showing how it constrains models, enables all-order beta-function vanishing, and aids in predicting particle masses.

## Contribution

It introduces the concept of coupling reduction as a scheme-independent method applied to particle physics models, including supersymmetric theories, with significant phenomenological implications.

## Key findings

- Coupling reduction functions satisfy renormalization group equations.
- Reduced couplings can lead to theories with vanishing beta-functions.
- Predictions for top and Higgs masses were made before experimental discovery.

## Abstract

The idea of reduction of couplings in renormalizable theories will be presented and then will be applied in Particle Physics models. Reduced couplings appeared as functions of a primary one, compatible with the renormalization group equation and thus solutions of a specific set of ordinary differential equations. If these functions have the form of power series the respective theories resemble standard renormalizable ones and thus widen considerably the area covered until then by symmetries as a tool for constraining the number of couplings consistently. Still on the more abstract level reducing couplings enabled one to construct theories with beta-functions vanishing to all orders of perturbation theory. Reduction of couplings became physics-wise truly interesting and phenomenologically important when applied to the standard model and its possible extensions. In particular in the context of supersymmetric theories it became the most powerful tool known today once it was learned how to apply it also to couplings having dimension of mass and to mass parameters. Technically this all relies on the basic property that reducing couplings is a renormalization scheme independent procedure. Predictions of top and Higgs mass prior to their experimental finding highlight the fundamental physical significance of this notion.