The hypothesis of the decay of neutrino mass eigenstates leads to a substantial modification of the appearance and disappearance probabilities of flavor eigenstates. We investigate the impact on the standard oscillation scenario caused by the decay of the heaviest mass eigenstate ν ₃ (with a mass m ₃ and a mean life τ ₃) to a sterile state in deep underground neutrino experiment. We find that the lower bound of 5.1 10⁻¹¹seV⁻¹ at 90% confidence level on the decay parameter τ ₃/m ₃ can be set if the neutral current data are included in the analysis, thus providing the best long-baseline expected limit so far. We also show that the ν _τ appearance channel would give only a negligible contribution to the decay parameter constraints. Our numerical results are corroborated by analytical formulae for the appearance and disappearance probabilities in vacuum (which is a useful approximation for the study of the invisible decay model) that we have developed up to the second order in the solar mass splitting and to all orders in the decay factor t/τ ₃.

中微子质量本征态衰变的假设导致风味本征态出现和消失概率的实质性修改。我们研究了在深部地下中微子实验中由最重质量本征态ν ₃（质量为m ₃和平均寿命为τ ₃）衰减到无菌状态对标准振荡场景的影响。我们发现衰减参数τ ₃ / m ₃在 90% 置信水平下的下限为 5.1 10 ^-11 seV ^-1 如果分析中包含中性线电流数据，则可以设置，从而提供迄今为止最好的长基线预期限制。我们还表明ν _τ外观通道对衰减参数约束的贡献可以忽略不计。我们的数值结果得到了真空中出现和消失概率的分析公式的证实（这是研究不可见衰变模型的有用近似），我们已经开发到太阳质量分裂的二阶和所有阶衰减因子t / τ ₃。