PT Journal
AU Pich, A
   Rodriguez-Sanchez, A
TI SU(3) analysis of four-quark operators: K -> pi pi and vacuum matrix elements
SO Journal of High Energy Physics
JI J. High Energy Phys.
PY 2021
BP 005
EP 43pp
VL 06
IS 6
DI 10.1007/JHEP06(2021)005
LA English
DE Chiral Lagrangians; CP violation; Effective Field Theories; Kaon Physics
AB Hadronic matrix elements of local four-quark operators play a central role in non-leptonic kaon decays, while vacuum matrix elements involving the same kind of operators appear in inclusive dispersion relations, such as those relevant in tau -decay analyses. Using an SU(3)(L) circle times SU(3)(R) decomposition of the operators, we derive generic relations between these matrix elements, extending well-known results that link observables in the two different sectors. Two relevant phenomenological applications are presented. First, we determine the electroweak-penguin contribution to the kaon CP-violating ratio epsilon '/epsilon, using the measured hadronic spectral functions in tau decay. Second, we fit our SU(3) dynamical parameters to the most recent lattice data on K -> pi pi matrix elements. The comparison of this numerical fit with results from previous analytical approaches provides an interesting anatomy of the Delta I = 1/2 enhancement, confirming old suggestions about its underlying dynamical origin.
ER