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Register a new userNew CP-violation and preferred-frame tests with polarized electrons
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We used a torsion pendulum containing $sim 9 times 10^{22}$ polarized electrons to search for CP-violating interactions between the pendulums electrons and unpolarized matter in the laboratorys surroundings or the sun, and to test for preferred-frame effects that would precess the electrons about a direction fixed in inertial space. We find $|g_{rm P}^e g_{rm S}^N|/(hbar c)< 1.7 times 10^{-36}$ and $|g_{rm A}^e g_{rm V}^N|/(hbar c) < 4.8 times 10^{-56}$ for $lambda > 1$AU. Our preferred-frame constraints, interpreted in the Kostelecky framework, set an upper limit on the parameter $|bm{tilde {b}}^e| leq 5.0 times 10^{-21}$ eV that should be compared to the benchmark value $m_e^2/M_{rm Planck}= 2 times 10^{-17}$ eV.
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We used a torsion pendulum containing $approx 10^{23}$ polarized electrons to search new interactions that couple to electron spin. We limit CP-violating interactions between the pendulums electrons and unpolarized matter in the earth or the sun, test for rotation and boost-dependent preferred-frame effects using the earths rotation and velocity with respect to the entire cosmos, and search for exotic velocity-dependent potentials between polarized electrons and unpolarized matter in the sun and moon. Finally, we find that the gravitational mass of an electron spinning toward the galactic center differs by less than about 1 part in $10^{21}$ from an electron spinning in the opposite direction. As a byproduct of this work, the density of polarized electrons in Sm$ $Co$_5$ was measured to be $(4.19pm 0.19)times 10^{22} {rm cm}^{-3}$ at a field of 9.6 kG.
Measurements of CP--violating observables in neutrino oscillation experiments have been studied in the literature as a way to determine the CP--violating phase in the mixing matrix for leptons. Here we show that such observables also probe new neutrino interactions in the production or detection processes. Genuine CP violation and fake CP violation due to matter effects are sensitive to the imaginary and real parts of new couplings. The dependence of the CP asymmetry on source--detector distance is different from the standard one and, in particular, enhanced at short distances. We estimate that future neutrino factories will be able to probe in this way new interactions that are up to four orders of magnitude weaker than the weak interactions. We discuss the possible implications for models of new physics.
We introduce the CP violating scalar leptoquark $S_3$ to explain the measured values of the lepton universality ratios $R_{K^{(*)}}$. We derive constraints on the CP-even and CP-odd components of the leptoquark Yukawa couplings stemming from effects in $b to s mu mu$ and $B_s$ mixing. For the $b to s mu mu$ processes we impose $R_{K^{(*)}}$, $mathcal{B}(B_s to mu^+ mu^-)$, as well as CP-sensitive angular asymmetries $A_{7,8,9}$, whereas in the $B_s$ mixing sector $Delta M_s$ and $S_{psiphi}$ are considered. Combining the constraints within the $S_3$ model reveals that a large CP phase with a definite sign is perfectly viable for a leptoquark of mass below a few TeV. For larger mass of the $S_3$ leptoquark the CP phase is suppressed due to the observables pertaining to the $B_s$ system. We provide predictions of direct and mixing-induced CP asymmetries in $B to K mu mu$ that could reveal the presence of the novel CP phase.
We study leptonic CP violation from a new perspective. For Majorana neutrinos, a new parametrization for leptonic mixing of the form $V=O_{23} O_{12} K_{a}^{i}cdot O$ reveals interesting aspects that are less clear in the standard parametrization. We identify several important scenario-cases with mixing angles in agreement with experiment and leading to large leptonic CP violation. If neutrinos happen to be quasi-degenerate, this new parametrization might be very useful, e.g., in reducing the number of relevant parameters of models.
Three possibilities for the origin of CP violation are discussed: (1) the Standard Model in which all CP violation is due to one parameter in the CKM matrix, (2) the superweak model in which all CP violation is due to new physics and (3) the Standard Model plus new physics. A major goal of B physics is to distinguish these possibilities. CP violation implies time reversal violation (TRV) but direct evidence for TRV is difficult to obtain.
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