New physics in \epsilon' from chromomagnetic contributions and limits on   Left-Right symmetry
  New physics in the chromomagnetic flavor changing transition s->dg* can avoid the strong GIM suppression of the Standard Model and lead to large contributions to CP-violating observables, in particular to the epsilon' parameter, that we address here. We discuss the case of the Left-Right symmetric models, where this contribution implies bounds on the phases of the right-handed quark mixing matrix, or in generic models with large phases a strong bound on the Left-Right symmetry scale. To the leading order, a numeric formula for epsilon' as a function of the short-distance coefficients for a wide class of models of new physics is given. 
Stefano Bertolini, Jan O. Eeg, Alessio Maiezza, Fabrizio Nesti
hep-ph