Special Semester on Cohomology in Arithmetic, CRM, Fall 2020

p-adic L-functions and Euler systems (in honor of Bernadette Perrin-Riou)

September 21-25, 2020

Organisers: Henri Darmon, Adrian Iovita and Antonio Lei



Tentative speakers and participants (to be confirmed):
Rebecca Bellovin (UCL), Denis Benois (Bordeaux), Laurent Berger (Lyon), Massimo Bertolini (Essen), Christophe Breuil (Orsay), Kazim Buyukboduk (UC Dublin), Antonio Cauchi (Laval), Francesc Castella (UC Santa Barbara), Charlotte Chan (Princeton), Mirela Ciperiani (Texas), Pierre Colmez (Jussieu), Samit Dasgupta (Duke), Ellen Eischen (Oregon), Olivier Fouquet (Orsay), Francesca Gatti (UPC) Ming-Lun Hsieh (Sinica), Ralph Greenberg (Washington), Dimitar Jetchev (EPFL), Lin Jie (Essen), Kazuya Kato (Chicago), Guido Kings (Regensburg), Shinishi Kobayashi (Kyushu), Masato Kurihara (Keio), Ruochuan Liu (Peking), Zheng Liu (Princeton), David Loeffler (Warwick), Kenkichi Nakamura (Saga), Jan Nekovar (Jussieu), Wieslawa Niziol (Lyon), Tadashi Ochiai (Osaka), Victor Rotger (Barcelona), Karl Rubin (UC Irvine), Peter Schneider (Munster), Chris Skinner (Princeton), Florian Sprung (Arizona State), Rodolfo Venerucci (Essen), Otmar Venjakob (Heidelberg), Shanwen Wang (Fudan), Sarah Zerbes (UCL)


Outline:
In Iwasawa Theory, one of the central questions is the study of the Iwasawa main conjecture, which relates the characteristic ideal of the Selmer group of a motive to its p-adic L-function (when it exists). This in turn leads to information on the Bloch-Kato conjecture, a generalization of the Birch and Swinnerton-Dyer conjecture. Cases of the Iwasawa main conjecture have been established using the machinery of Euler systems, which are collections of cohomology classes satisfying certain norm relations and are related to the L-function of a motive and were first introduced and exploited in the late 80s and early 90s in the works of Thaine, Kolyvagin, Rubin, and Kato.

Bernadette Perrin-Riou, one of the influential, pioneering figures in Iwasawa Theory in the 1990s, is widely acclaimed for the influential ideas she has brought to the subject. Her deep study of the Euler system originally constructed by Kato led to the introduction of her fundamental ``big logarithm map" (often refereed as the ``Perrin-Riou map" nowadays), which is a far reaching generalisation of the Coleman power series and is one of the key ingredients in establishing links between Euler systems and p-adic L-functions. Her work also initiated the study of higher rank Euler systems and has been a source of inspiration for many further developments in this direction. Likewise, her p-adic analogue of the Gross-Zagier formula has opened up an area of enquiry that remains active and fertile to the present day. All these, as well as many other important contributions of Perrin-Riou, continue to serve as a model and a guide for today's research in Iwasawa Theory. This workshop is therefore dedicated to the celebration of her 65th birthday.

In the first decade of this century, further progress in the theory of Euler systems was stymied by the fact that few instances were known beyond the basic examples (circular units, elliptic units, Heegner points, and Beilinson elements) introduced and exploited by Thaine, Rubin, Kolyvagin and Kato respectively. Around 2010, the scope of Kato's construction was extended to encompass p-adic families of cohomology classes arising from Beilinson-Flach elements, and diagonal cycles in triple products of Kuga-Sato varieties, with application to the Birch and Swinnerton conjecture in analytic rank zero, in the spirit of the early work of Coates and Wiles. Important progress was then made in establishing the Euler system norm compatibilities of Beilinson-Flach elements. This has opened the floodgates for a wide variety of new Euler system constructions, applying notably to the Rankin-Selberg convolution of two modular forms, Siegel modular forms on GSp(4) and GSp(6), as well as Hilbert modular surfaces. At around the same time, and quite independently, a markedly different strategy has been proposed for studying diagonal on triple products based on congruences between modular forms instead of $p$-adic deformations, leading to remarkable constructions whose scope has the potential to surpass the more traditional approach based on norm-compatible elements. Finally, important progress arising from the method of Eisenstein congruences offer a powerful complementary approach, greatly contributing to the power, usefulness, and widening appeal of Euler system techniques.


The workshop will precede the annual Quebec-Maine conference which will take place that year at Laval University on Saturday and Sunday (September 26-27). The workshop will end on Friday at noon so that those who wish to attend can travel to Quebec City in the afternoon. (A roughly 3 hour trip by train or by bus.)