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Yoav Achiman

Publications and source records attributed to Yoav Achiman.

12 recordsLinked to original sources
arXiv2008

Spontaneous CP Violation in next to minimal renormalizable SUSY SO(10)

The minimal renormalizable SUSY SO(10) model is a very compact and predictive theory. It was very popular till one realized that it cannot account for the masses of the neutrinos. The best cure to this problem is to add the 120 Higgs representaion, the 'next to minimal' version. To reduce the number of free parameters, it was suggested in recent papers to use only real parameters in the superpotential and induce CP violation via complex VEVs. This is what one usually calls 'spontaneous CP violation'. The number of free parameters turned out, then, to be even smaller than in the original minimal model and good fits to all known masses and mixings were obtained. Out of those papers only that of Aulakh and Garg discusses how CP is spontaneously violated. Some heavy MSSM singlet VEVs generate a phase at high scale and CP violationis carried down to the CKM matrix by the mixing of the scalar MSSM doublets. They study the model in great detail and give a large set of solutions. As a proof of principle, two of the solutions are shown to induce realistic phenomenological fits. It is not clear, however, how the right physical solution is obtained. I study the way solutions for spontaneous CP violation affect the scalar potential. The one that gives the lowest minimum of the potential, in terms of a given set of parameters, is the right physical one. In the way of doing so, I will prove that complex MSSM singlet VEVs lead actually to lower minima than the real (CP conserving) ones. This proves that CP is spontaneously violated in this model.

hep-ph↗
arXiv2007

Spontaneous CP Violation in SUSY SO(10)

A scenario is suggested for spontaneous CP violation in non-SUSY and SUSY- SO(10). The idea is to have a scalar potential which generates spontaneously a phase, at the high scale, in the VEV that gives a mass to the RH neutrinos. As a possible realization the case of the minimal renormalizable SUSY SO(10) is discussed in detail and one finds that a phase is induced in the CKM matrix. It is also pointed out that, in these models, the scales of Baryogenesis, Seesaw, Spontaneous CP violation and Spontaneous U(1)PQ breaking are all at the same order of magnitude.

hep-ph↗
arXiv2007

A Scenario for Spontaneous CP Violation in SUSY SO(10)

A scenario is suggested for spontaneous CP violation in non-SUSY and SUSY SU(10). The idea is to have a scalar potential which generates spontaneously a phase, at the high scale, in the VEV that gives a mass to the RH neutrinos. The case of the minimal renormalizable SUSY SO(10) is discussed in detail. The high scale CP breaking induces a phase in the CKM matrix as well. It is also pointed out that, in these models, the scales of Baryogenesis, Seesaw, Spontaneous CP violation and Spontaneous U(1)_QP breaking are all of the same order of magnitude.

hep-ph↗
arXiv2004

Can One Phase Induce All CP Violations Including Leptogenesis?

In the framework of a SUSY SO(10) model a phase is generated spontaneously for the B-L breaking VEV. Fitting this phase to the observed CP violating K,B decays all other CP breaking effects are uniquely predicted. In particular, the amount of Leptogenesis can be explicitly calculated and found to be in the right range and sign for the BAU.

hep-ph↗
arXiv2001

Gauge Mediated Proton Decay in a Renormalizable SUSY SO(10) with Realistic Mass Matrices

Proton decay via d=5 operators is excluded by now not only in the framework of SUSY SU(5) but also its extensions like SUSY SO(10) are on the verge of being inconsistent with d=5 decays. It is reasonable therefore to suppress, e.g. by a symmetry, the d=5 operators and to consider gauge boson induced d=6 decays. This is suggested in several recent papers in the framework of models with a lighter $ M_X$. We discuss here explicitly the fermionic sector of such a renormalizable SUSY SO(10) with realistic mass matrices. We find that the recently ``observed'' large leptonic mixing leads to an enhancement of the nucleon decay channels involving $μ$'s and in particular the $μ^+π^o$, $μ^+π^-$ modes.

hep-ph↗
arXiv2001

Large Quark Rotations Neutrino Oscillations and Proton Decay

The large freedom in the SM fermionic mass matrices allows for large LH and LH quark rotations. This is a natural possibility in view of the observed large leptonic mixing. Proton decay and especially its gauge mediated decay is sensitive also to those mixing angles which are non-relevant in the SM. A model with realistic mass matrices and large rotations is presented.. It is shown that the large leptonic mixing leads to enhancement of the proton decay branching ratios involving muons.

hep-ph↗
arXiv2000

Large Quark Rotations, Neutrino mixing and Proton Decay

Right-handed (RH) rotations do not play a role in the Standard Model, and only the differences of the LH mixing angles are involved in ${\bf V}_{\scr \textrm{CKM}}$. This leads to the huge freedom in the fermionic mass matrices. However, that is no more true in extensions of the Standard Model. For example in GUTs large RH rotations of the quarks can be related to the observed large neutrino mixing or in particular, all mixing angles are relevant for the proton decay. We present a simple realistic non-SUSY SO(10) GUT with large RH and LH mixing and study the corresponding nucleon decay rates.

hep-ph↗
arXiv1999

Large Right Handed Rotations, Neutrino Oscillations and Proton Decay

Right Handed (RH) rotations are not observable in the standard model (SM). The freedom is used to give the phenomenologically correct mass matrices all kind of different forms and this is one of the reasons for the proliferation of models for the fermionic masses. The SM must be however extended and in most extensions, RH currents appear at higher energy scales. At those energies the RH rotations are not irrelevant any more, they can affect neutrino oscillations, proton decay, baryon assymetry, R-parity violating interactions etc. We study possible implications of large RH mixing in GUTs. Those are interesting not only because large mixing induce large effects. They are intimately related to large lepton mixing in GUTs, via a relation between LH mixing of the leptons and the RH ones of the d-quarks ,(``$d - \ell$ duality'') and can change considerably the branching ratios of proton decay. Observation of proton decay channels as well as neutrino oscillations will teach us about RH rotations and will reduce, therefore, considerably the freedom in the fermionic mass matrices. Some interesting examples are studied in detail. In particular a new $E_6$ model which realizes naturally a $d$ - $\ell$ duality by mixing with exotic $E_6$ fermions.

hep-ph↗
arXiv1999

Are Right-Handed Mixings Observable?

Asymmetric mass matrices can induce large RH mixings. Those are non- measurable in the SM but are there and play an important role in its extensions. The RH rotations are in particular relevant for the proton decay, neutrino properties and baryon asymmetry. E.g. large RH mixings lead to kaon dominated proton decay even without SUSY and could be the reason for a large neutrino mixing. By studying those phenomena one can learn about the RH rotation matrices and this can reduce considerably the arbitrariness in the present fermionic mass study.

hep-ph↗
arXiv1997

Dominance of the Nucleon Decay K-channels in $P_{LR}$ invariant SO(10)

RH rotations of the fermionic mass matrices are not observable in the standard model, but dictate the details of the proton decay in GUTs. $P_{LR}$ symmetry in the two light families leads to a full RH mixing. We give two versions of suitable broken $P_{LR}$ invariant SO(10) which leads to nucleon decay modes similar to those of SUSY-GUTs with rates in the range of observability of superKamiokande and ICARUS.

hep-ph↗
arXiv1994

Fritzsch Texture in SUSY-SO(10) with Large Neutrino Mixing

Fritzsch's texture is imposed on {\em all} mass matrices in a SUSY-SO(10) via a family $U(1)_{PQ}$ symmetry. The observed charged fermion parameters fix the $ν$-masses and mixing, while the later are evolved from the GUT scale to low energies using the RG. Large $\sin^2 2θ_{12}$ results. As in a SUSY-GUT no intermediate scale is allowed, the RH-neutrino scale is the unification one and this gives in our model $Δm_{12}^2 \approx {10}^{-10} eV^2$, in accordance with the vacuum oscillation solution to the solar-$ν$ puzzle.

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