Recursive constructions in amplitudes are a strong feature that requires careful analytic continuation with momentum shift to yield the full, correct, physical amplitudes. If not done systematically, an undetermined contact term would arise. We study the All-Line Transverse (ALT) shift, which we developed for on-shell recursion of amplitudes for particles of any mass. Our method allows for a nice and clean determination of the constructibility of the underlying theory. We apply the shift to the QED, electroweak theory, and higher-spin Compton scattering. The ALT shift framework allows consistent treatment in dealing with contact term ambiguities for renormalizable massive and massless theories, which we show can be useful in studying real-world amplitudes with massive spinors.
Bio:
Zhen Liu is currently an Associate Professor at the University of Minnesota. Zhen received his Ph.D. from the University of Pittsburgh in 2015, M.Sc. from the University of Wisconsin-Madison in 2011 and B.Sc. from Zhejiang University in 2009. After completing his Ph.D., Zhen conducted postdoctoral research in the Theory Department at Fermi National Accelerator Laboratory between 2015-2018 and Maryland Center for Fundamental Physics at the University of Maryland between 2018-2020. Zhen's research has a broad scope on phenomenology in high energy physics, spanning from new physics searches at collider facilities, such as the LHC and various future colliders (CEPC, muon colliders), neutrino facilities, such as the DUNE and ArgoNeuT experiments, as well as small-scale experiments.
Tencent Meeting：935-639-094
Prof. Jia Liu