CP Violation In Theories Research Articles

Development of the Measurement System for the Search of an Electric Dipole Moment of the Electron with Laser-Cooled Francium Atoms

We plan to measure the permanent electric dipole moment (EDM) of the elec- tron, which has the sensitivity to the CP violation in theories beyond the standard model by using the laser-cooled francium (Fr) atom. This paper reports the present status of the EDM measurement system. A high voltage application system was constructed in order to produce the strong electric field (100 kV /cm) needed for the experiment. After condi- tioning, the leakage current was 10 pA when a high voltage of 43 kV was applied. Also, a drift of an environmental field was measured at the planned location of the Fr-EDM experiment. The drift is suppressed at present down to the level of 10 pT by installing a 4-layer magnetic shield. Improvements are still needed to reach the required field stability of 1 fT.

τpolarization asymmetries inB+→τ+ντγandBc+→τ+ντγ

We study the lepton polarization asymmetries in the radiative leptonic B decays of $B^+\to l^+\nu_{l}\gamma$ and $B^+_{c}\to l^+\nu_{l}\gamma$. We concentrate on the transverse component of the $\tau$ lepton asymmetries in the tau decay modes due to CP violation in theories beyond the standard model to search T violating effect.

T-violating muon polarization inK+→μ+νγ

We study the T violating transverse muon polarization in the decay of $K^+\to \mu^+\nu\gamma$ due to CP violation in theories beyond the standard model. We find that the polarization asymmetry could be large in some CP violation models and it may be detectable at the ongoing KEK experiment of E246 as well as the proposed BNL experiment.

Spontaneous CP violation in theories with low-energy supersymmetry.

The problem of strong CP violation in theories with low-energy supersymmetry is studied. Special emphasis is given to theories with spontaneous CP violation. It is found that supersymmetric versions of the Nelson models only receive contributions to \ensuremath{\Theta}\ifmmode\bar\else\textasciimacron\fi{} of order (${m}_{g}$/${M}_{\mathrm{GUT}}$) or at the three-loop level. The resulting \ensuremath{\Theta} is of order ${10}^{\mathrm{\ensuremath{-}}13}$ or less. This improves on the nonsupersymmetric Nelson models where \ensuremath{\Theta} arises at the one-loop level. Constraints on the mechanism for spontaneously breaking CP invariance in supersymmetric models are found.