Bridging grant application for T2K/-Canada: Improved measurements of neutrino oscillations and interactions

中微子有质量，可以改变味道，这一事实对我们对宇宙的理解产生了深远的影响：从星系是如何进化的，到为什么今天只有物质而没有反物质。为了进一步了解这一现象，T2K实验测量了中微子从日本东海的J-PARC实验室到富山的超级神冈探测器（距离295公里）时是如何改变味道的。T2K的长期目标是精确测量中微子和反中微子传播之间的任何差异，以寻找物质-反物质的差异。为了在这种测量上取得进展，实验必须减少其系统的不确定度。目前最重要的不确定性与我们对T2K探测器中中微子如何与原子核相互作用的不完全理解有关。

The fact that neutrinos have mass and can change flavors has a profound impact on our understanding of the universe: from how galaxies evolved to why today there is only matter and no antimatter. To learn more about this phenomenon, the T2K experiment measures how neutrinos can change flavors when they travel from the J-PARC laboratory in Tokai Japan to the Super-Kamiokande detector in Toyama, a distance of 295km. The long-term goal of T2K is to measure precisely any difference between neutrino and antineutrino propagation to search for matter-antimatter differences. To make progress on this measurement the experiment must reduce its systematic uncertainties. The most important uncertainties today have to do with our incomplete understanding of how neutrinos interact with the nuclei in T2K's detectors. The short term-goals of this program are: 1. Work to improve the neutrino event generator that T2K uses to simulate neutrino interactions. This model is currently the state of the art, and a version is in use by the DUNE experiment. 2. Make cross section measurements with the T2K Near Detector, focusing on neutrino interactions that produce pions. These measurements will be key for both the current and next generation experiments. 3. Extend the reach of T2K by working on the joint fits using both T2K and NOvA, a similar experiment based in the US. Because of the statistical precision of both, the treatment of the correlations in systematic effects is crucial. 4. Work with the existing York group to measure coherent pion production and to maintain the Optical Transition Monitor for T2K, in preparation for the new OTR installation in 2021. This is an application for a bridging grant to support Harris's research program for two years, until the renewal of the T2K-Canada Project Grant in 2021. In July 2019 Harris started as a Professor at York University and was admitted to the T2K collaboration. The proposed research program on T2K will expand the important role that Canada already plays in the experiment by leveraging Harris's experience with neutrino beamlines and with neutrino interaction measurements and modeling. This proposal requests funding to support a postdoc at 50% and two graduate students (Rowan Zaki and Damandeep Kaur), also at 50%. The impact of this work will extend far beyond that of the T2K experiment. The neutrino interaction measurements and model improvements produced will be inputs to other current and future neutrino propagation experiments. The Optical Transition Monitor is a promising technology for future high power proton beam measurements. Finally, the group supported here will learn simulation techniques, statistics, coding in a complex software environment, data analysis, and working in large international collaborations. This will serve the group well in whatever steps they take next.