Parity-odd fragmentation functions

Abstract

Quantum chromodynamics is a non-Abelian gauge theory of strong interactions, in which the parity symmetry can be violated by the nontrivial [Formula: see text]-vacuum tunneling effects. The [Formula: see text]-vacuum induces the local parity-odd domains. Those reactions that occur in these domains can be affected by the tunneling effects and quantities become parity-odd. In this paper we consider the fragmentation process where parity-odd fragmentation functions are introduced. We present the fragmentation functions by decomposing the quark–quark correlator. Among the total 16 fragmentation functions, eight of them are parity conserved, and the others are parity violated. They have a one-to-one correspondence. Positivity bounds of these one-dimensional fragmentation functions are shown. To be explicit, we also introduce an operator definition of the parity-odd correlator. According to the definition, we give a proof that the parity-odd fragmentation functions are local quantities and vanish when sum over all the hadrons [Formula: see text].