Simple supercuspidal L-packets of split special orthogonal groups over dyadic fields

Abstract: We consider the split special orthogonal group $\mathrm{SO}{N}$ defined over a $p$-adic field. We determine the structure of any $L$-packet of $\mathrm{SO}{N}$ containing a simple supercuspidal representation (in the sense of Gross--Reeder). We also determine its endoscopic lift to a general linear group. Combined with the explicit local Langlands correspondence for simple supercuspidal representations of general linear groups, this leads us to get an explicit description of the $L$-parameter as a representation of the Weil group of $F$. Our result is new when $p=2$ and our method provides a new proof even when $p\neq2$.