报告题目：Celestial CFT from CHY Formalism: Center Charge and Finite Size Effect

报告人：喻明 研究员 （中国科学院理论物理研究所）

报告时间：2024年3月28日（周四）下午15:30-16:30

报告地点：北洋园校区49教410室

报告摘要：

Scattering amplitudes in gauge theories can be calculated either by bulk theories in 4d Minkowski space-time($Mink_4$), or perceived as the correlation functions in celestial CFT(CCFT) living in the celestial sphere at null infinity, where  an infinite-dimensional asymptotic symmetry, BMS group,  resides.

Another well developed method is the CHY formalism, which  formulates the scattering amplitude in terms of the correlation functions on a 2d world sheet, on which an ambitwistor string theory  is defined. The relationship between CHY theory and  CCFT is encoded in scattering equations, which are  algebraic equations lacking of analytical solutions in general. So we start from the CHY formalism, take the collinear limit, then find a nice operator formalism for the CCFT. In particular, the center charge $c$ is calculated to be 36  for the CCFT related to the  4d Yang-Mills theory. It then follows that the 4d cosmological constant naturally  arises as the finite size effect in 2d CCFT, which is calculated by the method of  $ar{T}$ perturbed CCFT.

报告人简介：

1982年毕业于湖南大学物理系，同年考取教育部委托四川大学代培出国预备研究生。
1988年8月在丹麦玻尔物理研究所获博士学位，同年去意大利国际理论物理中心做博士后。
1990年12月被聘为理论物理研究所副研究员。
1996年被聘为理论物理所研究员、博士生导师。