K→ππhadronic matrix elements of left-right current-current operators

Abstract

Effective $\ensuremath{\Delta}S=1$ four-fermion operators involving left- and right-handed currents are relevant in left-right gauge extensions of the Standard Model and scalar extension of the Yukawa sector. They induce $K\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}$ decays which are strictly constrained by experimental data, typically resulting in strong bounds on the new physics scales or parameters. We evaluate the $K\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}$ hadronic matrix elements of such operators within the phenomenological framework of the chiral quark model. The results are consistent with the estimates used in a previous work on TeV scale left-right symmetry, thus confirming the conclusions obtained there.