T-odd andCP-odd aplanarities ine+e−colliders

We consider possible tests of CP violation or new strong-interacting sectors at future colliders, for instance $e^{+}$ $e^{\mathrm{-}}$. These tests minimize the flavor identification needed. In the case of the standard model no sizable observable is found, even if the Higgs sector becomes strongly interacting. The mean values of the simplest T-odd operators involving electron and positron polarizations and initial or final momenta are forbidden by the chiral-conserving interactions. More complicated observables involving correlations between final momenta and electron or positron polarizations can in principle have nonvanishing expectation values. However, the effect is proportional to a very small phase shift between left-handed and right-handed amplitudes. On the contrary, in theoretical schemes beyond the standard model, with significant chirality-flip couplings to fermions, either new sources of CP violation or new strong-interacting forces could be tested below the threshold of production of new particles.