Towards the detection of parity symmetry breaking in chiral molecules

We propose an optical rotation experiment to detect the electroweak parity-violating energy difference (PVED) between the two enantiomers of a chiral molecule. For some chiral molecules, it is shown theoretically that at low enough temperature, in the range from mK to few K, the competition between the PVED, tunneling between the two enantiomers and thermal effects leads to an enantiomeric excess in the thermodynamic equilibrium which is able to produce an optical rotation measurable by state-of-the-art ultrasensitive polarimeters. By means of mechanisms inhibiting tunneling, the sample would keep the enantiomeric excess at higher temperatures. Suitable chiral molecules are pointed out.