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

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## Abstract

In his monograph Arthur (The endoscopic classification of representations: orthogonal and symplectic groups, Colloquium Publications, American Mathematical Society, Providence, 2013) 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.

## Mathematics Subject Classification

Primary 22E50 Secondary 11F70## Notes

### Acknowledgements

The author wants to thank his thesis advisor James Arthur for his generous support and constant encouragement when this work was carried out. He also wants to thank the hospitality of the Institute for Advanced Study, where he finished writing up the current version. During his stay at IAS, he was supported by the National Science Foundation No. DMS-1128155 and DMS-1252158. At last, the author wants to thank the referee for many helpful comments and suggestions.

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