Song Cheng , Jinpeng Liu , Zhengwei Liu , Ziwen Liu

Dongsheng Ge

Friday, March 20, 2026 4:00 PM - 5:30 PM

Shuangqing-B627

Zoom 230 432 7880 (BIMSA)

Composite defect Quantum Field Theory represents a new regime where analytical tools are still at hand, though spacetime symmetries are further broken by introducing a sub-defect inside a conventional defect system. We have constructed explicitly such a composite defect model in terms of $d=3-\epsilon$ vector $O(N)$ models via localized interactions. This model allows for unitary Wilson-Fisher fixed points and is shown perturbatively to satisfy a weak C-theorem for the subdefect along the localized RG flows. Through further studies, this model is found to be identical to a two-dimensional long-range Ising model with a pining type interface. Such a pining interface appears to be non-factorizing in the IR limit, as opposed to what the factorizing conjecture suggests. This talk is based on 2408.04428, 2505.15018 and ongoing works.

Dr. Dongsheng Ge received his PhD degree at Ecole Normale Superieur in Paris in 2020. After that, he has performed a postdoc at the University of Warsaw in Poland and then at the University of Osaka in Japan. Currently he is a postdoc fellow at YMSC in Tsinghua University. His interests include holographic duality, defects in quantum field theories and their relation to quantum information.