CKMCPviolation in a minimal SO(10) model for neutrinos and its implications

Abstract

A minimal supersymmetric SO(10) model with one 10 and one 126 Higgs superfield has recently been shown to predict all neutrino mixings as well as the solar mass difference squared in agreement with observations. Two assumptions critical to the predictivity and success of the model are that: (i) the superpotential includes only renormalizable terms, thereby limiting the number of free parameters and (ii) the triplet term in the type II seesaw formula for neutrino mass dominates, leading to the sum rule M ν = c(M d − M e ) that is responsible for large mixings. However, CKM CP phase is constrained to be in the second or third quadrant requiring a significant non-CKM component to CP violation to explain observations. We revisit this issue using type I seesaw formula for neutrino masses and obtain the following results: (i) we show that the above sumrule responsible for large mixing angles can also emerge in type I seesaw models; the detailed predictions are however not compatible with present data for any choice of CP phases. (ii) We then show that addition of a nonrenormalizable term restores compatibility with neutrino data and CKM CP violation both in type I and type II cases. We further find that (iii) the MSSM parameter tan β ≥ 30 in the type I model and (iv) lepton flavor violation and lepton electric dipole moments which are accessible to proposed experiments in both type I and type II models. We also discuss the unification of the gauge couplings in type I model which requires an intermediate scale.

CPviolation in a minimal renormalizable supersymmetricSO(10)model and beyond

“…Non-renormalizable operators are invoked in ref. [23], while in ref. [24] a 120 dimensional Higgs extension is considered (with an additional parity symmetry), in order to restore the agreement with the data.…”

“…δCKM and the electron mass formula When complex Yukawa couplings are considered, it is claimed that a successful fit of the electron mass forces the CKM phase to take values in the second or third quadrant [22,23,24], thus requiring an extension of the model to recover the measured CP violation.…”

“…When complex Yukawa couplings are taken into account, recent analyses [22,23,24] show that the fit of the lepton mixings may improve, but the CabibboKobayashi-Maskawa (CKM) phase is forced to the second or third quadrant by the electron mass fit, thus requiring significant contributions to CP violation from other sources. Non-renormalizable operators are invoked in ref.…”

Lepton Flavour Violation in the Minimal SO(10) GUT Model and in the Standard Model with additional Heavy Dirac Neutrinos

“…The constants in these vertices are defined by mSUGRA SUSY breaking mediation mechanism [12] and the underlying GUT model, here chosen to be the minimal SO(10) model [4,5,6,7,8,9]. The model contains two SO(10) Higgs superfields, 10 and 126 in the Yukawa sector, and additional Higgs superfields 126 and 210 to preserve the supersymmetry at the GUT scale [23] and to break the SO(10) symmetry to [23,24].…”

“…The simpler of these models, SM extended by heavy (quasi-)Dirac neutrinos [1,2,3] (called model A here) has only additional heavy (quasi-) Dirac neutrino fields compared to the SM field content. The second model [4,5,6,7,8,9] (model B) is based on the minimal supersymmetric standard model (MSSM) with heavy right-handed neutrinos [10,11], with model parameters determined by the underlying GUT model and through the minimal SUGRA (mSUGRA) SUSY-breaking mediation mechanism [12].…”