Speaker
Vittorio Lubicz
(Universita' Roma Tre)
Description
We describe our study of the chromomagnetic operator O_CM, which appears in the effective Hamiltonian describing DS=1 transitions in and beyond the Standard Model.
Having dimension 5, the chromomagnetic operator is characterized by a rich pattern of mixing with other operators of equal and lower dimensionality. We have computed the coefficients of the mixing with the various dimension 5 operators using one loop lattice perturbation theory and determined the power-divergent mixing coefficient with the scalar density non-perturbatively. The numerical computations have been carried out by using the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 + 1 + 1 dynamical quarks, at three values of the lattice spacing and several values of the light quark masses.
In this talk, we will mainly describe the non-perturbative parts of the calculation and present preliminary results for the matrix element of the chromomagnetic operator between pion and kaon states.
Primary author
Vittorio Lubicz
(Universita' Roma Tre)
Co-authors
Davide Meloni
(Universita' Roma Tre)
Guido Martinelli
(SISSA)
Haris Panagopoulos
(University of Cyprus)
Marios Kosta
(University of Cyprus)
Martha Constantinou
(University of Cyprus)
Roberto Frezzotti
(Universita' Tor Vergata)
Silvano Simula
(INFN, Sezione di Roma Tre)
