The solar-neutrino problem, 1995

Summary The status of the Solar-Neutrino Problem (SNP), as is seen in 1995, is reviewed. Basically, there are two principal solutions to the SNP: i) withstandard neutrino (neutrino of SM of electroweak interactions) and ii) withnon-standard neutrino (neutrino beyond the SM). Actually, one can distinguish three solar-neutrino problems: the deficit of⁸B neutrinos, the deficit of⁷Be neutrinos and the HOMESTAKE/KAMIOKANDE conflict. The first problem probably can be solved with small correlated changes of nuclear cross-sections and the change of the central temperature of the Sun. The deficit of⁷Be neutrinos looks like the key problem. The HOMESTAKE/KAMIOKANDE conflict strongly disfavours or excludes the standard neutrino (nuclear/astrophysical solution to the SNP). MSW conversion gives a most plausible explanation to the SNP.     

Resonant amplification of neutrino spin rotation in matter and the solar-neutrino problem

It is shown that in the presence of matter there can occur resonant amplification of the flavor-changing neutrino spin rotation in transverse magnetic fields, which is roughly analogous to the Mikheyev-Smirnov-Wolfenstein effect in neutrino oscillations. Possible consequences for solar neutrinos are briefly discussed.     

Cosmological bounds on a left-right symmetric model

The right-handed neutrino cross sections of the processes ν_L + ? → ν_R + ? and ν_R + ? → ν_R + ?, where ? is a relativistic lepton, are calculated in the SU(2)_L × SU(2)_R × U(1) model. According to a cosmological criterion the parameters of the model are bounded. In particular we obtain the bound $\text{M}{}_{\mathrm{<mtext>W</mtext>}}{}_{\mathrm{<mtext>R</mtext>}}\text{? 30 M}{}_{\mathrm{<mtext>W</mtext>}}{}_{\mathrm{<mtext>L</mtext>}}$, assuming the neutrinos are Dirac four-component particles.     

The inhomogeneous slab,a rigorous solution to the propagation problem

A rigorous solution based on an integral equation to investigate the propagation in an inhomogeneous slab of arbitratry index profile is given.     

The number of neutrinos and the left-right symmetric model

The meaning of N _v in the Left-Right Symmetric Model (LRSM) is discussed. In its original definition N _v is the number of neutrinos or generations of leptons, so, in the Standard Model its value is three. However the determination of N _v in experiments and in astrophysical observations is subject to different theoretical interpretations. We present arguments that gives N _v as a parameter of the LRSM. Using an experimental value for the rate Γ_inv/Γ_ll? we calculate the bound $2.90leq N_{v_{LR}}leq 3.04 (90% {? C.L.})$, where $N_{v_{LR}}$ is a function of the left-right mixing angle ?. This range is less restrictive than the one of the standard model.     

具有整体代对称性的左右对称模型中的中微子质量

本文基于具有整体U(1)代对称性的SU(2)_L×SU(2)_R×U(1)模型推导了轻子的味混合矩阵,对中微子的质量问题进行了研究.在本文的模型中,产生轻子Dirac质量的汤川耦合拉格朗日密度具有整体U(1)代对称性,所以,模型中的带电轻子质量矩阵和中微子Dirac质量矩阵是Fritzsch形式的.但是,中微子除了具有Dirac质量,一般还具有Majorana质量,在这种一般情况下, 关键词： 中微子质量 轻子味混合矩阵 左右对称模型 代对称性