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The e ective neutrino mass of neutrinoless double-beta decays:how possible to fall into a well

Zhi-zhong Xing; Zhen-hua ZhaoSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The neutrinoless double-beta (0ν2β) decay is currently the only feasible process in particle and nuclear physics to probe whether massive neutrinos are the Majorana fermions. If they are of the Majorana nature and have a normal mass ordering, the e?ective neutrino mass term mee of a 0ν2β decay may su?er signi?cant cancellations among its three components and thus sink into a decline,resulting in a “well” in the three-dimensional graph of |mee| against the smallest neutrino mass m1 and the relevant Majorana phase ρ. We present a new and complete analytical understanding of the ?ne issues inside such a well, and identify a novel threshold of |mee| in terms ofthe neutrino masses and ?avor mixing angles: |mee|? = m3 sin2 θ13 in connection with tan θ12 = m1/m2 and ρ = π. This threshold point, which links the local minimum and maximum of |mee|, can be used to signify observability or sensitivity of the future 0ν2β-decay experiments. Given current neutrino oscillation data, the possibility of |mee| < |mee|? is found to be very small. |

A Realization of Effective SUSY with Strong Unification

Chun Liu; Zhen-hua ZhaoSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

A natural model of realizing the effective supersymmetry is presented. Two sets of the Standard Model-like gauge group G1×G2 are introduced, where Gi = SU(3)i×SU(2)i ×U(1)i, which breakdiagonally to the Standard Model gauge group at the energy scale M ? 107 GeV. Gauge couplings in G1 are assumed much larger than that in G2. Gauge mediated supersymmetry breaking is adopted. The first two generations (third one) are charged only under G1 (G2). The effective supersymmetry spectrum is obtained. How to reproduce realistic Yukawa couplings is studied.Fine-tuning for an 126 GeV Higgs is much reduced by the large A term due to direct Higgs-messenger interaction. Finally, G2 is found to be a non-trivial realization of the strong unificationscenario in which case we can predict #11;s(MZ) without real unification |

13 and the Higgs mass from high scale supersymmetry

Chun Liu ; Zhen-hua ZhaoSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

In the framework in which supersymmetry is used for understanding fermion masses rather than stabilizing the electroweak scale, we elaborate on the phenomenological analysis for the neutrino physics. A relatively large sin #18;13 ? 0.13 is naturally obtained. The model further predicts vanish-ingly small CP violation in neutrino oscillations. While the high scale supersymmetry genericallyresults in a Higgs mass of about 141 GeV, our model reduces this mass to 126 GeV via introducingSU(2)L triplet fields which make the electroweak vacuum metastable (with a safe lifetime) and also contribute to neutrino masses. |

MINOS Anomaly as A Signal of Lorentz Violation

Chun Liu; Jin-tao Tian; Zhen-hua ZhaoSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Recently, the MINOS collaboration reported an anomaly that the mass-squared difference and mixing angle of ?ν? ? ν?τ are both different from that of ν? ? ντ . In this letter, based on the framework of neutrino oscillations, terms that break the Lorentz symmetry are used as perturbation to explain this anomaly and satisfactory results are got. Remarkably, some surprising conclusions, one of which is that in the high energy limit (hundreds of GeV) neutrino oscillation pattern will be independent of energy, are also arrived. |

A Modified Friedberg-Lee symmetry for the TM1 neutrino mixing

Zhen-hua ZhaoSubjects: Physics >> Nuclear Physics

In this letter, we put forward a special neutrino mass matrix which is invariant under a modified Friedberg-Lee (FL) transformation?νe→νe?2θ?and?νμ,τ→νμ,τ+θ?with?θ?being a space-time independent element of the Grassmann algebra. Compared to the original FL symmetry (with the transformation?νe,μ,τ→νe,μ,τ+θ) which results in the TM2 neutrino mixing, the modified FL symmetry will lead us to the TM1 mixing which has a better agreement with the experimental results. While the original FL symmetry has to be broken in order to produce a realistic neutrino mass spectrum, the modified FL symmetry is allowed to remain intact and give us a vanishing?m1. A combination of the FL symmetry with the?μ-τ?reflection symmetry is also discussed. |

On the four-zero texture of quark mass matrices and its stability

Zhi-zhong Xing; Zhen-hua ZhaoSubjects: Physics >> Nuclear Physics

We carry out a new study of quark mass matricesMu(up-type) and Md(down-type) which are Hermitian and have four zero entries, and find a new part of the parameter space which was missed in the previous works. We identify two more specific four-zero patterns ofMu and Md with fewer free parameters, and present two toy flavor-symmetry models which can help realize such special and interesting quark flavor structures. We also show that the texture zeros of Mu and Md are essentially stable against the evolution of energy scales in an analytical way by using the one-loop renormalization-group equations. |

750 GeV diphoton excess confronted with a top-pion in the TTM model

Yu-Chen Guo; Chong-Xing Yue; Zhen-hua ZhaoSubjects: Physics >> Nuclear Physics

The latest LHC data suggest an intriguing excess at?mγγ=750?GeV which apparently requires an explanation from the beyond standard model physics. In this note we explore the possibility for this signal to arise from a top-pion in the Top Triangle Moose model which can be viewed as a dimensional-deconstruction version of the top-color assisted technicolor model. We demonstrate that the observed excess can be accommodated by and has important implications for this interesting model. |

On the breaking of mu-tau flavor symmetry

Zhen-hua ZhaoSubjects: Physics >> Nuclear Physics

In light of the observation of a relatively large?θ13, one has to consider breaking the?μ-τ?symmetry properly which would otherwise result in a vanishing?θ13?(as well as?θ23=π/4). Therefore, we investigate various symmetry-breaking patterns and accordingly identify those that are phenomenologically viable. Furthermore, the symmetry-breaking effects arising from some specific physics (e.g., the renormalization group equation running effect) are discussed as well. |

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