Rare Decays Probing Physics Beyond the Standard Theory

TL;DR

This paper reviews how rare decays of quarks and leptons serve as sensitive probes for discovering new physics beyond the Standard Theory by analyzing flavor-changing neutral processes.

Contribution

It discusses the role of rare decays in indirectly searching for new physics and explores potential deviations from Standard Theory predictions in flavor-changing processes.

Findings

Rare decays are powerful tools for probing new physics.

Flavor-changing neutral decays are highly suppressed in the Standard Theory.

Potential new flavor structures could manifest in rare decay processes.

Abstract

In the last 50 years we have seen how an initially ad-hoc and not widely accepted theory of the strong and electroweak interactions (Standard Theory: ST) has correctly predicted the entire accelerator based experimental observations with incredible accuracy (with the important exception of neutrino oscillation experiments). Decays of the ST particles (quarks and leptons), which are rare due to some symmetry of the theory, have played an important role in the formalism of the ST. These rare decays have been powerful tools to search for new particle interactions with the ST particles, which may not necessarily have the same symmetries. In this article, I will describe the indirect search for evidence of new physics (NP) using quark and lepton flavour changing neutral decays, which are highly suppressed within the ST, and constitute strong probes of potential new flavour structures.