L-packets of quasisplit $GSp(2n)$ and $GO(2n)$

TL;DR

This paper extends Arthur's characterization of L-packets from quasisplit symplectic and orthogonal groups to their similitude groups, confirming they satisfy conjectural endoscopic identities.

Contribution

It provides a new description of L-packets for similitude groups, building on Arthur's work and verifying key conjectural identities.

Findings

L-packets for similitude groups are explicitly characterized.

The packets satisfy the expected endoscopic character identities.

Extension of Arthur's results to a broader class of groups.

Abstract

In his monograph (2013) Arthur characterizes the L-packets of quasisplit symplectic groups and orthogonal groups. By extending his work, we characterize the L-packets for the corresponding similitude groups with desired properties. In particular, we show these packets satisfy the conjectural endoscopic character identities.