Rare Kaon Decay Experiments

在CERN NA 62实验上对K ~+到π ~+中微子反中微子（KPNN）的超稀有K ~+衰变进行高精度测量，将是对夸克味物理最深入的探索之一。分支比对许多新的物理模型很敏感，这些模型是其他反应无法达到的，它们扩展了标准模型（SM）来解决其相当大的问题。KPNN分支分数的SM预测被广泛认为在5%水平上具有理论上的稳健性。只有极少数的环主导夸克过程可以用这种确定性来预测。SM中KPNN分支分数的抑制到10-10级允许SM之外的物理对分支分数做出显着贡献，其增强高达SM预测的五倍。可以预测SM对KPNN的贡献的确定性将允许新物理学的重大发现潜力，其在夸克味物理学中具有独特的灵敏度，并且它允许在LHC的范围内探测与夸克耦合的大多数新物理模型。此外，KPNN的高精度测量对许多新物理模型很敏感，这些模型的质量尺度远远超出了LHC的直接范围。NA 62预计将在SM级观测100个KPNN事件，覆盖新物理模型贡献的大部分参数空间。它还将研究许多其他罕见或禁止的反应，以寻找暗物质，重无菌中微子，中性π衰变和辐射过程。

High precision measurement of the ultra-rare kaon decay K+ to pi+ neutrino anti-neutrino (KPNN) at the CERN NA62 experiment will be one of the most incisive probes of quark flavor physics. The branching ratio is sensitive to many new physics models not accessible by other reactions which extend the Standard Model (SM) to solve its considerable problems. The SM prediction for the KPNN branching fraction is broadly recognized to be theoretically robust at the 5% level. Only a precious few accessible loop-dominated quark processes can be predicted with this level of certainty. The suppression of the KPNN branching fraction in the SM to the level 10-10 allows physics beyond the SM to contribute dramatically to the branching fraction with enhancements of up to factors of five above SM predictions. The certainty with which the SM contribution to KPNN can be predicted will permit a significant discovery potential for new physics with sensitivity unique in quark flavor physics and it allows probing of most models of new physics that couple to quarks within the reach of the LHC. Furthermore, a high precision measurement of KPNN is sensitive to many models of new physics with mass scales well beyond the direct reach of the LHC. NA62 expects to have sensitivity for observing 100 events at the SM level for KPNN covering most of the parameter space for new physics models to contribute. It will also study many other rare or forbidden reactions to search for dark matter, heavy sterile neutrinos, neutral pion decays, and radiative processes.