标题： 中微子秘密地转化为较轻的粒子，以取悦KATRIN和宇宙 显示英文标题

标题： Neutrinos secretly converting to lighter particles to please both KATRIN and the cosmos

摘要： 在粒子物理的标准模型和标准宇宙学的框架内，宇宙微波背景（CMB）和重子声波振荡（BAO）的观测对中微子质量之和设定了严格的限制。如果这些限制被满足，旨在探测中微子质量低至$\sim 0.2$eV 的即将到来的 KATRIN 实验只会观察到零信号。我们表明，通过引入新的相互作用来处理活性中微子的质量，可以使 KATRIN 可观测到的中微子质量范围与宇宙学限制相兼容。在此场景下，中微子会在早期宇宙中一个约$T\sim$keV 温度附近共振产生中间态，从而转化为新的稳定轻粒子，这导致密度涨落的抑制程度远不如标准模型那么显著。 显示英文摘要

摘要： Within the framework of the Standard Model of particle physics and standard cosmology, observations of the Cosmic Microwave Background (CMB) and Baryon Acoustic Oscillations (BAO) set stringent bounds on the sum of the masses of neutrinos. If these bounds are satisfied, the upcoming KATRIN experiment which is designed to probe neutrino mass down to $\sim 0.2$ eV will observe only a null signal. We show that the bounds can be relaxed by introducing new interactions for the massive active neutrinos, making neutrino masses in the range observable by KATRIN compatible with cosmological bounds. Within this scenario, neutrinos convert to new stable light particles by resonant production of intermediate states around a temperature of $T\sim$ keV in the early Universe, leading to a much less pronounced suppression of density fluctuations compared to the standard model.