On the non-triviality of the p-adic Abel-Jacobi image of generalised Heegner cycles

Speaker: 

Ashay Burungale

Institution: 

UCLA

Time: 

Tuesday, October 14, 2014 - 3:00pm to 4:00pm

Location: 

RH340P

Generalised Heegner cycles are associated to a pair of an elliptic Hecke eigenform and a Hecke character over an imaginary quadratic extension K. Let p be an odd prime split in K. We describe the non-triviality of the p-adic Abel-Jacobi image of generalised Heegner cycles modulo p over anticyclotomic extensions of K.

Explicit reciprocity law for generalised Heegner cycles

Speaker: 

Francesc Castella

Institution: 

UCLA

Time: 

Tuesday, October 14, 2014 - 2:00pm to 3:00pm

Location: 

RH340P

We will describe an explicit reciprocity law for generalised Heegner cycles, relating the images of certain twists of these classes under the Bloch-Kato dual exponential map to certain Rankin-Selberg L-values, and explain the applications of this formula to the proof of certain rank 0 cases of the Bloch-Kato conjecture. This is a joint work with M.-L. Hsieh.

Discrete logarithms in small characteristic

Speaker: 

Daqing Wan

Institution: 

UCI

Time: 

Tuesday, October 7, 2014 - 2:00pm

Location: 

RH340P

In this talk, I will explain the mathematical ideas and questions arising from the recent breakthrough BGJT algorithm for discrete logarithms over finite fields of small characteristic.  This is joint work with Q. Cheng and J. Zhuang (ANTS 2014).

 

Igusa’s conjecture for exponential sums

Speaker: 

Wim Veys

Institution: 

University of Leuven (KULeuven), Belgium

Time: 

Friday, September 5, 2014 - 3:00pm

Host: 

Location: 

RH440R

In joint work with Raf Cluckers, we propose a conjecture for exponential sums which generalizes both a conjecture by Igusa and a local variant by Denef and Sperber, in particular, it is without the homogeneity condition on the polynomial in the phase, and with new predicted uniform behavior. The exponential sums have summation sets consisting of integers modulo p^m lying p-adically close to y, and the proposed bounds are uniform in p, y, and m. We give evidence for the conjecture, by showing uniform bounds in p, y, and in some values for m. On the way, we prove new bounds for log-canonical thresholds which are closely related to the bounds predicted by the conjecture.

Slopes of modular forms

Speaker: 

Liang Xiao

Institution: 

UC Irvine

Time: 

Tuesday, May 27, 2014 - 2:00pm

Location: 

RH 340P

I will explain several conjectures and results regarding the slope distribution of Up operator action on the space of modular forms.  Most notably, we prove that the slopes of modular forms with a highly p-divisible characters roughly form unions of arithmetic progressions.  This is a joint work with Daqing Wan and Jun Zhang.

Local newforms for SO(2n+1)

Speaker: 

Pei-Yu Tsai

Institution: 

Caltech

Time: 

Friday, May 16, 2014 - 2:00pm

Location: 

RH 340P

When a holomorphic modular form is a newform, its L-function has nice analytic properties and associates a cuspidal automorphic representation, which is a restricted product of local representations. To recover the newform from the representation, Casselman considered the fixed line of the congruence subgroups of GL(2) at the conductor level on the local representations. A vector on this line shall encode the conductor, the L-function and the \epsilon-factor of the representation. This is called the theory of newforms for GL(2). Similar theory has been established for some groups of small ranks as well as GL(n). In this talk I will introduce one for SO(2n+1).

Overconvergent Eichler-Shimura morphisms for modular curves

Speaker: 

Fucheng Tan

Institution: 

Michigan State University

Time: 

Tuesday, May 20, 2014 - 2:00pm

Location: 

RH 340P

We construct the Eichler-Shimura morphisms for families of overconvergent modular forms via Scholze's theory of pro-etale site, as well as the Hodge-Tate period maps on modular curves of infinite level. We follow some of the main ideas in the work of Andreatta-Iovita-Stevens. In particular, we reprove the main result in their paper. Since we work entirely on the generic fiber of the modular curve, log structures will not be needed if we only consider the Eichler-Shimura morphism for cusp forms.  Moreover, the well-established theory of the Hodge-Tate period map for Shimura varieties of Hodge type may allow us to generalize the construction to more general Shimura varieties. This is a joint work with Hansheng Diao.

Diophantine properties of fields with finitely generated Galois group

Speaker: 

Michael J. Larsen

Institution: 

Indiana University and MSRI

Time: 

Tuesday, April 29, 2014 - 2:00pm

Host: 

Location: 

RH 340P

I will discuss a number of related conjectures concerning the rational points of varieties (especially curves and abelian varieties) over fields with finitely generated Galois group and present some evidence from algebraic numebr theory, Diophantine geometry, and additive combinatorics in support of these conjectures.

Towards a definition of Shimura curves in positive characteristics

Speaker: 

Jie Xia

Institution: 

Columbia University

Time: 

Tuesday, May 13, 2014 - 2:00pm

Location: 

RH 340P

Shimura varieties are defined over complex numbers and generally have number fields as the field of definition. Motivated by an example constructed by Mumford, we find conditions which guarantee a curve in char. p lifts to a Shimura curve of Hodge type. The conditions are intrinsic in positive characteristics and thus they shed light on a definition of Shimura curves in positive characteristics. 

In this talk, I will start with modular curves, and discuss the moduli interpretation of Shimura curves. Then I will present such a condition in terms of isocrystals. Time permitting, I would show a deformation result on Barsotti-Tate groups, which serves as a key step in the proof. 
 

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