The Fundamental Constants in Physics and their Time Dependence

TL;DR

This paper explores the potential time variation of fundamental constants in physics, especially the fine-structure constant and QCD scale, discussing theoretical implications and experimental efforts to detect such changes over cosmological timescales.

Contribution

It analyzes the relationship between variations in fundamental constants and grand unification theories, and reviews experimental approaches in quantum optics to detect these changes.

Findings

Astrophysical observations suggest a possible variation of the fine-structure constant at 10^{-15} per year.

Relations between the variation of alpha and the QCD scale are derived from grand unification.

Experiments in quantum optics are discussed as methods to detect time variations of fundamental constants.

Abstract

We discuss the fundamemtal constants in the Standard Model of particle physics, in particular possible changes of these constants on the cosmological time scale. The Grand Unification of the observed strong, electromagnetic and weak interactions implies relations between time variation of the finestructure constant alpha and the QCD scale $\Lambda_c$. The astrophysical observation of a variation implies a time variation of $10^{-15} / year$. Several experiments in Quantum Optics, which were designed to look for a time variation of $\Lambda_c$, are discussed.