
Light Degrees of Freedom from String/M theory framework 
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Institute of Theoretical Physics  Chinese Academy of Sciences  Key Laboratory of Theoretical Physics  Seminar  Title 题目  Light Degrees of Freedom from String/M theory framework  Speaker 报告人  Dr. Chakrit Pongkitivanichkul  Affiliation 所在单位  中国科学院高能物理研究所  Date 日期  2016年11月9日（星期三）下午 17:00 PM  Venue 地点  Room 6620,ITP new Building/理论物理所新楼6620报告厅  Abstract 摘要  I will discuss two topics of light degrees of freedom from string/M theory, namely, Axion Like Particles (ALPs) and neutrinos. The string/M theory Axiverse  a plethora of very light ALPs with a vast range of masses  is arguably a generic prediction of string/M theory. String/M theory also tends to predict that the early Universe is dominated by moduli fields. When the heavy moduli decay, before nucleosynthesis, they produce dark radiation in the form of relativistic ALPs. Generically one estimates that the number of relativistic species (Neff) grows with the number of axions in the Axiverse, in contradiction to the observations that Neff < 4. I will explain this problem in detail and suggest some possible solutions to it. The second part of the talk I will discuss the origin of neutrino mass from SO(10) arising from M Theory compactified on a G2manifold. This is linked to the problem of the breaking of the extra U(1) gauge group, in the SU(5) x U(1) subgroup of SO(10), which is achievable via a (generalised) KoldaMartin mechanism. The resulting neutrino masses arise from a combination of the seesaw mechanism and induced Rparity breaking contributions. The rather complicated neutrino mass matrix is analysed for one neutrino family and it is shown how phenomenologically acceptable neutrino masses can emerge.  Contact Person 联系人  李田军 



