Pinning down the New Minimal Supersymmetric GUT

We show that generic ${\bf{10\oplus 120\oplus {\bar {126}}}}$ fits of fermion masses and mixings, using real superpotential couplings but with complex `Higgs fractions' leading to complex yukawa couplings in the effective MSSM, \emph{overdetermine}(by one extra constraint) the superpotential parameters of the New Minimal Supersymmetric SO(10) GUT\cite{nmsgut}. Therefore fits should properly be done by generating the 24 generic fit parameters from the 23 parameters of the NMSGUT superpotential, given $\tan\beta$ as input. Each numerical fit then \emph{fully specifies} the parameters of the NMSGUT. An analysis of all its implications, modulo only the residual uncertainty of supersymmetry breaking parameters, is now feasible. Thus the NMSGUT offers the possibility of a confrontation between the scale of gauge unification and the fit to fermion masses due to their extractable common dependence on the NMSGUT parameters. If and when `smoking gun' discoveries of Supersymmetry and Proton decay occur they will find the NMSGUT fully vulnerable to falsification.Comment: Minor changes : (1) Abstract : Phrase "complex Higgs doublet vevs" made more precise and a conjunction deleted (2)References : Umlauts inserted in an author nam

Neutrino Masses and Mixings in a Predictive SO(10) Model with CKM CP Violation

It has recently been shown that a minimal SO(10) model with a single {\bf 10} and single {\bf 126} Higgs field breaking B-L symmetry predicts large solar and atmospheric mixings in agreement with observations if it is assumed that the neutrino mass obeys the type II seesaw formula. No additional symmetries need to be assumed for this purpose. Understanding CP violation in the renormalizable version of the model however requires a significant non-CKM source. In this paper we show that if we extend the model by the inclusion of a heavy {\bf 120} dimensional Higgs field, then it can accomodate CKM CP violation while remaining predictive in the neutrino sector. Among the predictions are:(i) solar mixing angle in the observed range; (ii)\theta_{13} in the range of 0.1 to 0.26; (iii) the Dirac phase close to maximal for the central value of the solar mixing angle.Comment: 16 pages, 10 figures, Comments are added, Typos are corrected, An erroneous sentence on discrete symmetry is modified, Results are unchange

Fermion masses and mixings in a renormalizable SO(10) x Z_2 GUT

We investigate a scenario in a supersymmetric SO(10) Grand Unified Theory in which the fermion mass matrices are generated by renormalizable Yukawa couplings of the $\mathbf{10} \oplus \mathbf{120} \oplus \bar{\mathbf{126}}$ representation of scalars. We reduce the number of parameters by assuming spontaneous CP violation and a \mathbbm{Z}_2 family symmetry, leading to nine real Yukawa coupling constants for three families. Since in the ``minimal SUSY SO(10) GUT'' an intermediate seesaw scale is ruled out and our scenario lives in the natural extension of this theory by the $\mathbf{120}$, we identify the vacuum expectation value (VEV) $w_R$ of $(\mathbf{10}, \mathbf{1}, \mathbf{3}) \in \bar{\mathbf{126}}$ with the GUT scale of $2 \times 10^{16}$ GeV. In order to obtain sufficiently large neutrino masses, the coupling matrix of the scalar $\bar{\mathbf{126}}$ is necessarily small and we neglect type II seesaw contributions to the light-neutrino mass matrix. We perform a numerical analysis of this 21-parameter scenario and find an excellent fit to experimentally known fermion masses and mixings. We discuss the properties of our numerical solution, including a consistency check for the VEVs of the Higgs-doublet components in the SO(10) scalar multiplets.Comment: 13 pages, 1 figure; material, clarifications and references added, final version for Phys. Lett.

Constraint on the heavy sterile neutrino mixing angles in the SO(10) model with double see-saw mechanism

Constraints on the heavy sterile neutrino mixing angles are studied in the framework of a minimal supersymmetric ${\rm SO}(10)$ model with {\it double see-saw mechanism}. A new singlet matter in addition to the right-handed neutrinos is introduced to realize the double see-saw mechanism. The minimal ${\rm SO}(10)$ model gives an unambiguous Dirac neutrino mass matrix, which enables us to predict the masses and the mixing angles in the enlarged $9 \times 9$ neutrino mass matrix. Mixing angles between the light Majorana neutrinos and the heavy sterile neutrinos are shown to be within the LEP experimental bound on all ranges of the Majorana phases.Comment: 16 pages, 4 figures; the version to be published in Eur. Phys. J.

Strong suppression of superconductivity by divalent Ytterbium Kondo-holes in CeCoIn_5

To study the nature of partially substituted Yb-ions in a Ce-based Kondo lattice, we fabricated high quality Ce_{1-x}Yb_xCoIn_5 epitaxial thin films using molecular beam epitaxy. We find that the Yb-substitution leads to a linear decrease of the unit cell volume, indicating that Yb-ions are divalent forming Kondo-holes in Ce_{1-x}Yb_xCoIn_5, and leads to a strong suppression of the superconductivity and Kondo coherence. These results, combined with the measurements of Hall effect, indicate that Yb-ions act as nonmagnetic impurity scatters in the coherent Kondo lattice without serious suppression of the antiferromagnetic fluctuations. These are in stark contrast to previous studies performed using bulk single crystals, which claim the importance of valence fluctuations of Yb-ions. The present work also highlights the suitability of epitaxial films in the study of the impurity effect on the Kondo lattice.Comment: 5 pages, 4 figure

Radiative seesaw: a case for split supersymmetry

We revive Witten's mechanism for the radiative seesaw induced neutrino masses in SO(10) grand unified theory. We propose its extension to charged fermion masses as a possible cure for wrong tree level mass relations. We offer two simple realizations that can produce a realistic fermionic spectrum. The first one requires two 10 dimensional Higgses in the Yukawa sector and utilizes radiative effects for charged fermion masses. The second one trades one 10 for a 120 dimensional Higgs and leads to the SO(10) theory with less parameters in the Yukawa sector. The mechanism works only if supersymmetry is broken at the GUT scale while gauginos and higgsinos remain at TeV. This provides a strong rationale for the so called split supersymmetry.Comment: 12 pages, 2 figures, a few references and short comment on gluinos adde

Fermion mixings vs d=6 proton decay

It is well known, although sometimes ignored, that not only the d=5 but also d=6 proton decay depends on fermion mixings. In general we study carefully the dependence of d=6 decay on fermion mixings using the effective operator approach. We find that without specifying a theory it is impossible to make clear predictions. Even in a given model, it is often not possible to determine all the physical parameters. We point out that it is possible to make a clear test of any grand unified theory with symmetric Yukawa couplings. We discuss in some detail realistic theories based on SU(5) and SO(10) gauge symmetry.Comment: 12 pages, two new references, a new equation, and few correction