题    目: From S^1-gerbes over [G/G]to affine deformations of cotangent groupoids

主讲人:  戚铠川

单    位: 宾夕法尼亚州立大学

时    间: 2026年5月23日  15:00

地    点: 学院一楼报告厅

摘    要: For a compact connected Lie group G, I willexplain how the Kac-Moody S^1-central extension ofLG gives an explicit S^1-gerbe over the quotient stack[G/G], whose Dixmier-Douady class is the Alekseev-Malkin-Meinrenken class. I will then describe a generalmechanism suggested by this example: an S^1-centralextension of Lie groupoids, via nonzero symplecticreduction of cotangent groupoids, produces an affinedeformation of $TA*\mathcal {G rightrightarrowsA^*$. This is joint work with Dadi Ni.