# The Interplay between Tunneling and Parity Violation in Chiral Molecules

## TL;DR

This paper reviews how quantum tunneling and parity violation affect chiral molecules, explaining their behavior and energy differences.

## Contribution

The paper provides a comprehensive review of theoretical and experimental approaches to parity-violating energy differences in chiral molecules.

## Key findings

- Quantum tunneling allows stereomutation dynamics between L and R enantiomers.
- Parity-violating energy differences (PVED) can arise from electroweak interactions.
- Mean-field theory and decoherence are discussed as solutions to Hund’s paradox.

## Abstract

In this review, the concepts of quantum tunneling and parity violation are introduced in the context of chiral molecules. A particle moving in a double well potential provides a good model to study the behavior of chiral molecules, where the left well and right well represent the L and R enantiomers, respectively. If the model considers the quantum behavior of matter, the concept of quantum tunneling emerges, giving place to stereomutation dynamics between left- and right-handed chiral molecules. Parity-violating interactions, like the electroweak one, can be also considered, making possible the existence of an energy difference between the L and R enantiomers, the so-called parity-violating energy difference (PVED). Here we provide a brief account of some theoretical methods usually employed to calculate this PVED, also commenting on relevant experiments devoted to experimentally detect the aforementioned PVED in chiral molecules. Finally, we comment on some ways of solving the so-called Hund’s paradox, with emphasis on mean-field theory and decoherence.