应刘玉孝教授邀请，武汉大学物理科学与技术学院杜一剑副教授来我院进行学术交流，并作学术报告。欢迎广大师生届时参加！

题目：A graphic approach to gauge invariance induced identity

时间：2018年12月7日（周五）下午4:00

地点：齐云楼525报告厅

摘要：

All tree-level amplitudes in Einstein-Yang-Mills (EYM) theory and gravity (GR) can be expanded in terms of color ordered Yang-Mills (YM) ones whose coefficients are polynomial functions of Lorentz inner products and are constructed by a graphic rule. Once the gauge invariance condition of any graviton is imposed, the expansion of a tree level EYM or gravity amplitude induces a nontrivial identity between color-ordered YM amplitudes. Being different from traditional amplitude relations (such as Kleiss-Kuijf (KK) and Bern-Carrasco-Johansson (BCJ) relations), the gauge invariance induced identity includes polarizations in the coefficients. In this talk, I will introduce the graphic expansion of EYM and GR amplitudes. By a refined graphic rule, I will show that the gauge invariance induced identities are just proper combinations of traditional BCJ relations.  A graph-based BCJ relation will be established as a byproduct.

个人简介：

杜一剑，2005年毕业于浙江大学竺可桢学院取得学士学位，2010年浙江大学物理系取得博士学位。2010年-2015年先后在浙江大学、复旦大学、隆德大学（瑞典）从事博士后研究工作。2015年9月入职武汉大学物理科学与技术学院。研究方向为量子场论、弦论，近年来主要从事量子场论和弦论散射振幅新结构、新性质的研究。