Loophole in Search Beyond Grossman—Nir Bound

10th International Conference on Kaon Physics

Hou, George W.S.^1

Department of Physics, National Taiwan University, Taipei

10617, Taiwan^1

关键词: Explicit modeling;    Kinematic control;    Potential impacts;    W bosons;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/800/1/012024/pdf
DOI  :  10.1088/1742-6596/800/1/012024

来源: IOP

【 摘 要 】

The Grossman-Nir bound concept is robust, but the common perception of KL→ π0v v -9may be circumvented. Because of the blinding Kπ2(3) decay, K+decay experiments such as E787/E949 and the currently running NA62 kinematically exclude the "blinding zone". This offers an opportunity for the currently running KOTO experiment. With no kinematic control, if the KOTO experiment is able to veto all true background, it may discover KL→ π0+ X0, where X0is an invisible " dark " boson with mass mX0∼ mπ0 . This could happen with 2015 data at hand, which supposedly should allow KOTO to reach nominal GN bound sensitivity. An explicit model of gauged Lμ -LT, linked with muon g-2 hence with very light Z' , is given. Adding vector-like quarks that mix with usual quarks, W-boson loops induce s → dZ' and b → sZ' transitions. Besides realizing the scenario, the model provides further illustration of potential impact. Given that usual dark bosons linked with the photon are tightly constrained, KOTO has a unique opportunity to probe the muon-related dark sector.