报告题目 (Title)：O(D,D) string cosmology from double field theory
（双场理论下的O(D,D)弦宇宙学）
报告人 (Speaker)：Dr. Stephen Angus（韩国西江大学）
报告时间 (Time)：2025年9月24日(周三) 10:00-11:40
报告地点 (Place)：校本部 AJ204
邀请人 (Inviter)：尹璐
主办部门：理学院物理系
摘要 (Abstract)：
The
low-energy limit of string theory contains additional gravitational
degrees of freedom that are not present in general relativity. Together
with the metric, these fields are naturally embedded in the
O(D,D)-symmetric framework of double field theory (DFT). First I will
explain how the O(D,D) symmetry uniquely prescribes the interactions
between the extended gravitational sector and other matter, leading to
novel features beyond conventional string cosmology. Then I will present
the equations of motion for linear perturbations, and I will show how
the generalized conservation laws modify the conditions for conservation
of curvature perturbations. Finally, I will present some examples of
analytic solutions, including candidate models for bouncing cosmologies,
and I will explore how they may imply a non-Riemannian origin of the
universe.