Bay Area Algebraic Number Theory and Arithmetic Geometry Day 11

Saturday, December 5, 2015
University of California, Santa Cruz
Room: McHenry Library, room 1240


Jeremy Booher, Stanford University
Jayce Getz, Duke University
Matthew Greenberg, University of Calgary
Rachel Pries, Colorado State University
Zhiwei Yun, Stanford University


9:30-10:00 Coffee/Bagels
10:00-11:00 Rachel Pries
11:00-11:15 Coffee Break
Jayce Getz
1:45-2:45 Zhiwei Yun
Coffee Break
Jeremy Booher
Matthew Greenberg
Dinner, Laili Restaurant
Please RSVP to sdasgup2 (at) ucsc (dot) edu

Titles and Abstracts:

Jeremy Booher, "Geometric Deformations of Orthogonal and Symplectic Galois Representations"
For a representation of the absolute Galois group of the rationals over a finite field of characteristic p, we would like to know if there exists a lift to characteristic zero with nice properties. In particular, we would like it to be geometric in the sense of the Fontaine-Mazur conjecture: ramified at finitely many primes and potentially semistable at p. For two-dimensional representations, Ramakrishna proved that under technical assumptions odd representations admit geometric lifts. We generalize this to higher dimensional orthogonal and symplectic representations. The key ingredient is a smooth local deformation condition obtained by analysing unipotent orbits and their centralizers in the relative situation, not just over fields.

Jayce Getz, "Beyond endoscopy, hyperkloosterman sums, and the Kuznetsov formula"
We introduce the Langlands' beyond endoscopy proposal from the perspective of the Kuznetsov formula (following Sarnak and Venkatesh). Special attention will be paid to the analytic difficulties of the proposal and how certain modifications of the formula might provide avenues to surmount these difficulties.

Matthew Greenberg, "p-adic interpolation of branching laws and p-adic period integrals"
In this talk, I will describe the construction of a p-adic period integral interpolating, over balanced subsets of weight space, the period integral functional appearing in Ichino's special value formula for the triple product L-function. Since Ichino's formula relates period integrals to special values of L-functions, these p-adic period integrals can be considered as p-adic L-functions. The key step in the construction is proving that the classical branching laws for representations of GL2 x GL2 restricted to the diagonally embedded GL2 can be p-adically interpolated. This is joint work with Marco Seveso.

Rachel Pries, "The p-torsion invariants of non-ordinary Jacobians and Prym varieties"
In positive characteristic, an elliptic curve can be ordinary or supersingular. For abelian varieties of higher dimension, there are several invariants which can be used to generalize this distinction, including the p-rank, Newton polygon, or Ekedahl-Oort type. There are well-understood stratifications of the moduli space of principally polarized abelian varieties in positive characteristic by these invariants. In the first half of the talk, I will describe the current state of knowledge about which of these invariants occur for Jacobians of curves and how the Torelli locus intersects these strata. In the second half of the talk, I will discuss recent research with Ekin Ozman about p-ranks of Prym varieties.

Zhiwei Yun,"Taylor coefficients of L-functions for function fields"
In joint work with Wei Zhang, we prove a generalization of the Gross-Zagier formula in the function field setting. Our formula relates self-intersection number of certain cycles on the moduli of Drinfeld Shtukas for PGL(2) to higher derivatives of automorphic L-functions at the central point.


The closest parking is at the Hahn parking lot. Parking is free and no permit is required on Saturdays, as long as you park in a legal parking space and do not block emergency access, or park in spaces that are posted and reserved for special use. There is a foot bridge that connects the Hahn parking lot to McHenry Library. If you click on this map and zoom out one level, the bridge is indicated by a dotted line. Halfway through the bridge, there is a path that leads to the left, but you want to ignore this path and continue straight until the end of the bridge. After crossing the bridge, make a sharp left slightly downhill to enter the building at the first level. (The main entrance is actually on the second level, so if you enter at the main entrance you will have to take the elevator down one level.)

Here are printable maps: McHenry Library, and more specifically how to get to Hahn parking lot and walk to McHenry.


There is no formal registration, but if you plan to attend, we would appreciate an email to sdasgup2 at ucsc dot edu to help plan the event, especially if you plan to attend the dinner afterwards.


There will be a dinner following the conference at 6:00pm, at Laili Restaurant in Downtown Santa Cruz. Please send an email to sdasgup2 at ucsc dot edu if you plan to attend. Graduate students will be partially subsidized at the dinner. We thank the UC Santa Cruz Mathematics Department, the Math Research Center at Stanford University, and the UC Berkeley Mathematics Department for partial financial support.