Limits on asymmetric orthopositronium formation in high Z optically active molecules

Abstract

The proposed connection between the parity violating handedness of beta particles in radioactive decay and the sign (L) of biological chirality (the Vester-Ulbricht [V-U] hypothesis) is experimentally tested. The theoretically predicted asymmetry in triplet positronium formation ( A Ps ) is measured in several high Z optically active molecules using low energy positrons with a net helicity. We find A Ps <3×10 −4 in selenocystine ( Z =34) and thyroxine ( Z =53), excluding part of the theoretically predicted range of 4×10 −3 > A Ps >2×10 −6 in these molecules. The connection between these limits and limits on asymmetric radiolysis ( A R ) is made, with a new limit of A R >10 −9 being placed. This limit on A R , which is thirty times lower than a previous measurement in the amino acid leucine ( Z =6), is still not small enough to rule out the V-U hypothesis.