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Abstract:
In this talk, I will present some recent progress on loop integrands from several perspectives. At one loop, we derive a universal expansion for general gauge theories through single-cut reconstruction, leading to closed-form expressions in gauge theory, in particular for Yang–Mills theory. We further extend the single-cut reconstruction to one-loop gravity integrands and derive the corresponding double-copy BCJ and KLT relation at the level of loop integrands. Similar ideas can be generalized to higher loops, although subtleties arise in Yang–Mills theory. Nevertheless, we develop an algorithm for constructing higher-loop Yang–Mills integrands via single-cut recursion. These results suggest that the general philosophy of reconstructing integrands from cuts applies broadly to color-ordered loop integrands.
Biography:
Qu Cao received his Bachelor's degree from Zhejiang University in 2021. He will complete his doctoral studies in Theoretical Physics at Zhejiang University and the Institute of Theoretical Physics, Chinese Academy of Sciences, in 2026, under the supervision of Ellis Ye Yuan and Song He. He has twice received the National Graduate Scholarship and was awarded an National Natural Science Foundation of China doctoral research grant during his PhD. His research focuses on the analytic properties and underlying mathematical structures of perturbative scattering amplitudes in quantum field theory and string theory. He will join Westlake University as a Westlake Fellow in the summer of 2026.
Host: Prof. Kai Yan
Alternative online link：https://meeting.tencent.com/dm/EJrHFRN8Llei
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