The arithmetic fundamental lemma for regular semisimple elements

Let FF be a non-archimedean local field, let E/FE/F be the relevant quadratic extension, and let Sn(F)S_n(F), U(J01)(F)U(J_0\oplus 1)(F), and the matching relation be as defined above. For a regular semisimple element γSn(F)rs\gamma\in S_n(F)_{\rm rs}, let O(γ,1Sn(OF))O(\gamma,1_{S_n(\mathcal{O}_F)}) be the weighted orbital integral, let gg be a matching regular semisimple element when one exists, let KK be the stabilizer of the chosen self-dual lattice, and let ω(γ)\omega(\gamma) be the sign defined by the valuation formula in the paper.

The arithmetic fundamental lemma. For γSn(F)rs\gamma\in S_n(F)_{\rm rs},

O(γ,1Sn(OF))={ω(γ)O(g,1K),if γ matches gU(J01)(F)rs,0,if γ matches no gU(J01)(F)rs.O(\gamma,1_{S_n(\mathcal{O}_F)})= \begin{cases} \omega(\gamma)O(g,1_K),&\text{if }\gamma\text{ matches }g\in U(J_0\oplus 1)(F)_{\rm rs},\\\\ 0,&\text{if }\gamma\text{ matches no }g\in U(J_0\oplus 1)(F)_{\rm rs}. \end{cases}

This is the minuscule-case fundamental lemma for unitary groups. Equal-characteristic results and the pp-adic case for sufficiently large, unspecified residue characteristic were known according to the source; the general statement in the paper is presented as a conjecture.

Sources & referencesView supporting material

Primary source

Michael Rapoport, Ulrich Terstiege and Wei Zhang, “On the Arithmetic Fundamental Lemma in the minuscule case”, arXiv:1203.5827 (2013).

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