报告题目：Effective Dynamics of Loop Quantum Kaluza-Klein Cosmology

报告人：马永革 教授（北京师范大学）

报告时间：2026 年 9 月 3 日（周四）15 : 30-16 : 30

报告地点：北洋园校区 49 教 410 室

报告摘要：

The five-dimensional loop quantum Kaluza-Klein cosmology is constructed based on the symmetric reduction of the connection formulation of the full theory. Through semiclassical analysis, the effective scalar constraint for the cosmological model coupled with a dust field is derived, incorporating the quantum fluctuations of geometry as a subleading order correction. It demonstrates that the quantum model has the correct classical limit. The explicit solutions to the equations of motion show that the big bang and past big rip singularities in the classical model are avoided by a quantum bounce and a quantum collapse respectively in the effective model. In a particular scenario, the dynamical compactification of the extra dimension is realized, while the observable four-dimensional universe transitions through three distinct epochs: (i) a super-inflationary phase generating 55 e-folds, (ii) a decelerated expansion era, and (iii) a late-time accelerated expansion phase driven by quantum fluctuations. These results suggest that both cosmic inflation and dark energy may originate from the interplay between the compact extra dimension and quantum geometric effects.

报告人简介：

       马永革，北京师范大学物理与天文学院教授，北师大引力与相对论研究中心主任，国际圈量子引力学会指导委员会委员，研究领域：圈量力引力、广义相对论、规范引力理论、高能引力和宇宙学，曾主持完成国家自然科学基金重点项目等多个课题的研究，获得教育部2016年度高等学校科学研究优秀成果奖。