Searcharxiv⌕ Search

arXiv subjects

Julia Gordon

Publications and source records attributed to Julia Gordon.

22 records · Page 2Linked to original sources
arXiv2004

Motivic nature of character values of depth-zero representations

It is shown that the values of Harish-Chandra distribution characters on definable compact subsets of the set of topologically unipotent elements of symplectic or special orthogonal p-adic groups can be expressed as the trace of Frobenius action on virtual Chow motives. The result is restricted to a class of depth-zero representations that can be obtained by inflation from Deligne-Lusztig representations. The proof relies on arithmetic motivic integration.

math.RT↗
arXiv2002

Virtual Transfer Factors

The Langlands-Shelstad transfer factor is a function defined on some reductive groups over a p-adic field. Near the origin of the group, it may be viewed as a function on the Lie algebra. For classical groups, its values have the form q^c s, where s is -1, 0, or 1, q is the cardinality of the residue field, and c is a rational number. The function s partitions the Lie algebra into three subsets. This article shows that this partition into three subsets is independent of the p-adic field in the following sense. We define three universal objects (virtual sets in the sense of Quine) such that for any p-adic field F of sufficiently large residue characteristic, the F-points of these three virtual sets form the partition. The theory of arithmetic motivic integration associates a virtual Chow motive with each of the three virtual sets. The construction in this article achieves the first step in a long program to determine the (still conjectural) virtual Chow motives that control the behavior of orbital integrals.

math.RT↗
arXiv2002

Motivic Haar measure on reductive groups

We define a motivic analogue of the Haar measure for groups of the form G(k((t))), where k is an algebraically closed field of characteristic zero, and G is a reductive algebraic group defined over k. A classical Haar measure on such groups does not exist since they are not locally compact. We use the theory of motivic integration introduced by M. Kontsevich to define an additive function on a certain natural Boolean algebra of subsets of G(k((t))). This function takes values in the so-called dimensional completion of the Grothendieck ring of the category of varieties over the base field. It is invariant under translations by all elements of G(k((t))), and therefore we call it a motivic analogue of Haar measure. We give an explicit construction of the motivic Haar measure, and then prove that the result is independent of all the choices that are made in the process, even though we have no general uniqueness statement.

math.AG↗