Magnitude Of CP Violation Research Articles

Cancellations Between Two-Loop Contributions to the Electron Electric Dipole Moment with a CP-Violating Higgs Sector.

We present a class of cancellation conditions for suppressing the total contributions of Barr-Zee diagrams to the electron electric dipole moment (eEDM). Such a cancellation is of particular significance after the new eEDM upper limit was released by the ACME Collaboration, which strongly constrains the allowed magnitude of CP violation in Higgs couplings and hence the feasibility of electroweak baryogenesis (EWBG). Explicitly, if both the CP-odd Higgs-photon-photon (Z boson) and the CP-odd Higgs-electron-positron couplings are turned on, a cancellation may occur either between the contributions of a CP-mixing Higgs boson, with the other Higgs bosons being decoupled, or between the contributions of CP-even and CP-odd Higgs bosons. With a cancellation, large CP violation in the Higgs sector is still allowed, yielding successful EWBG. The reopened parameter regions would be probed by future neutron, mercury EDM measurements, and direct measurements of Higgs CP properties at the Large Hadron Collider Run II and future colliders.

Neutrino mixing anarchy: Alive and kicking

Neutrino mixing anarchy is the hypothesis that the leptonic mixing matrix can be described as the result of a random draw from an unbiased distribution of unitary three-by-three matrices. In light of the very strong evidence for a nonzero sin2⁡2θ13, we show that the anarchy hypothesis is consistent with the choice made by the Nature – the probability of a more unusual choice is 41%. We revisit anarchy's ability to make predictions, concentrating on correlations – or lack thereof – among the different neutrino mixing parameters, especially sin2⁡θ13 and sin2⁡θ23. We also comment on anarchical expectations regarding the magnitude of CP-violation in the lepton sector, and potential connections to underlying flavor models or the landscape.

Realization of the lepton flavor structure from point interactions

We investigate a 5d gauge theory on S1 with point interactions. The point interactions describe extra boundary conditions and provide three generations, the charged lepton mass hierarchy, the lepton flavor mixing and tiny degenerated neutrino masses after choosing suitable boundary conditions and parameters. The existence of the restriction in the flavor mixing, which appears from the configuration of the extra dimension, is one of the features of this model. Tiny Yukawa couplings for the neutrinos also appears without the see-saw mechanism nor symmetries in our model. The magnitude of CP violation in the leptons can be a prediction and is consistent with the current experimental data.

Realization of the lepton flavor structure from point interactions

We investigate a 5d gauge theory on $S^1$ with point interactions. The point interactions describe extra boundary conditions and provide three generations, the charged lepton mass hierarchy, the lepton flavor mixing and tiny degenerated neutrino masses after choosing suitable boundary conditions and parameters. The existence of the restriction in the flavor mixing, which appears from the configuration of the extra dimension, is one of the features of this model. Tiny Yukawa couplings for the neutrinos also appears without the see-saw mechanism nor symmetries in our model. The magnitude of CP violation in the leptons can be a prediction and is consistent with the current experimental data.

Upper limit onCPviolation in theBs0−B¯s0system

In a previous publication we noted that the time dependence of an incoherent $B^0-\bar{B}^0$ mixture undergoes a qualitative change when the magnitude of CP violation $\delta$ exceeds a critical value. Requiring, on physical grounds, that the system evolve from an initial incoherent state to a final pure state in a monotonic way, yields a new upper limit for $\delta$. The recent measurement of the wrong charge semileptonic asymmetry of $B_s^0$ mesons presented by the D0 collaboration is outside this bound by one standard deviation. If this result is confirmed it implies the existence of a new quantum mechanical oscillation phenomenon.

T-ODD ASYMMETRY IN TRILEPTONIC DECAY OF SCALAR LEPTON

The complex mass matrix for neutralinos could lead to T-violation in the neutralino decay. We analyze the successive decay of the scalar lepton into three leptons and the lightest neutralino, which is mediated by a heavier neutralino. If the magnitude of CP-violation is not small, T-odd asymmetry will be observed in the angular distribution of the three leptons.

T violation in neutralino decay

We show that in the supersymmetric standard electroweak theory the neutralino decay causesCP violating phenomena. It will be possible to observeT odd asymmetry in the angular distribution if the trilepton decay of theW boson is found. We also discuss the constraint on the magnitude ofCP violation by the electric dipole moment of the neutron.

Mixing angles andCPviolation in anSU(2)L×U(1)gauge model

Expressions for the mixing parameters are obtained in terms of mass ratios in the standard Weinberg-Salam model with permutation symmetry S/sub 3/ for six quarks. The CP-violating phase delta is taken into account and there are no arbitrary parameters except for the quark masses. In the lowest order, the angles defined by Kobayashi and Maskawa are sintheta/sub 1/ approx. = (m/sub d//(m/sub d/+m/sub s/))/sup 1/2/, sintheta/sub 2/ approx. = -((m/sub s//m/sub b/)/sup 2/-(m/sub c//m/sub t/)/sup 2/)/sup 1/2/, and sintheta/sub 3/=(m-italic/sub s//m/sub b/)/sup 2//costheta/sub 1/. The model can be consistent with the observed magnitude of CP violation. The b quarks decay predominantly into c quarks with lifetime of tau/sub b/ approx. = 10/sup -11/ sec.

Mass hierarchies and a formula for the Cabibbo angle in SU(2) L × U(1)

Form the observation that there is a three-fold hierarchy of quark and lepton masses we are led to impose a discrete symmetry on the lagrangian. As a consequence, two quark masses and all mixing angles are predicted with the following results: (i) tan θ c = (m d /m s ) 1 2 ; (ii) m b is predicted correctly; (iii) m t is predicted to be ∼ 20 GeV; (iv) the relation m e/ m μ ≈ m u/ m c emerges automatically; (v) a heavy meson containing a b quark is predicted to decay into charmed particles with a lifetime of ∼ 10 −11 s; (vi) the magnitude of CP violation in K L → 2π automatically is O(10 −3).