學術報告:The Neutrino CP measurements: Dirac & Majorana

來源:  發布時間:2019-06-10 09:34:29 點擊次數:

報告題目:The Neutrino CP measurements: Dirac & Majorana

報告人: 葛韶鋒博士(日本東京大學 Kavli IPMU)

報告時間: 2019611日上午10:00

報告地點: 物理學院新樓5樓多功能廳


The leptonic Dirac CP phase has profound physical consequences due to its connection with leptogenesis for explaining the existence of matter in the Universe. To some extent, the leptonic CP phase is even more important than the Higgs boson that provide mass for all fundamental particles. If we cannot understand the existence of matter, why we need to care about their mass.

I will first review the status of CP measurement and then introduce a new proposal with muon decay at rest (muDAR). Currently, accelerator neutrino experiments such as T2K, NOvA, and DUNE are the most promising for CP measurement. Nevertheless, they suffer from several problems of degeneracy, efficiency, sensitivity, and new physics such as non-unitarity mixing (NUM) and (vector, scalar, dark) non-standard interactions (NSI). The situation can be improved by adding a muon decay at rest (muDAR) source. With T2(H)K running in neutrino mode and muDAR in anti-neutrino mode, both using the same detector, the CP measurement becomes more precise can break the degeneracy between \delta and 180^o - \delta. Most importantly, muDAR can guarantee the CP sensitivity against NUM and NSI.  The same configuration can also apply to next-generation medium baseline reactor neutrino experiments like JUNO and RENO-50, enhancing their physics potential from just mass hierarchy to also CP. With only one source and no extra detectors, this dessign is much better than DAEdLAS which requires 3 sources, but only 20% duty factor and 4 times higher luminosity for each.

If neutrinos are Majorana particles, there is not just one Dirac CP phase, but also two Majorana CP phases. The nature of Majorana neutrinos can be probed in the neutrinoless double beta (0v2b) decay. Unfortunately, current global fit from neutrino oscillation experiments and cosmological observations indicate that the neutrino mass hierarchy should be normal. This seems not good for observing the 0v2b decay. But I will demonstrate that the situation is actually the opposite. The normal hierarchy can allow simultaneous determination of the two Majorana CP phases, which can never be true for the inverted mass hierarchy.


葛韶鋒博士,2002-2006年清華物理系本科,畢業時獲葉企孫獎;2006-2012年清華高能物理中心博士,2009年在美國德克薩斯州立大學奧斯汀分校聯合培養。2012-2014年獲日本學術振興會(JSPS)學者在日本高能加速器研究機構(KEK)、2014-2017年在德國海德堡馬普所MPIK從事理論研究。2017年至今獲美國加州大學伯克利分校和日本東京大學Kavli IPMU聯合聘請,擔任項目研究員;2017年獲美國費米國家加速器實驗室(Fermilab)中微子中心學者獎、并受邀于2018年夏天訪問研究三個月。獲聘上海交通大學李政道研究所,任李政道青年學者。主要研究領域為中微子、暗物質、對撞機物理的理論與唯象研究。共發表文章30篇,其中三篇PRL

邀請人:孫亮 教授

關閉信息】  【打印信息