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Newform theory for the full space via local Shimura correspondence and Waldspurger-type theorem

Research Project

Project/Area Number 18K13396
Research Category

Grant-in-Aid for Early-Career Scientists

Allocation TypeMulti-year Fund
Review Section Basic Section 11010:Algebra-related
Research InstitutionTokyo Institute of Technology

Principal Investigator

プルカイト ソーマ  東京工業大学, 理学院, 特任准教授 (30806592)

Project Period (FY) 2018-04-01 – 2025-03-31
Project Status Granted (Fiscal Year 2023)
Budget Amount *help
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2021: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2019: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2018: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
KeywordsLocal Hecke algebra / Local Newforms / Shimura correspondence / Whittaker functions / Iwahori Hecke algebra / mod p representation / Hecke algebra / Congruent numbers / Automorphic / Representation / Automorphic forms / Half-integral weight / Newforms / Waldspurger's formula
Outline of Annual Research Achievements

In a joint research with Moshe Baruch and Markos Karameris, we describe the subalgebra H of the metaplectic G:=\tilde{SL}_2(Q_p) of level p^n (with trivial and quadratic character) that is supported in the maximal compact K using generators and relations, in particular we show that it is a commutative 2n dimensional algebra and give a complex basis of eigenvectors under the left action of H on I(n) where the later is the induced representation from K_0(p^n) to K. In particular we obtain two level p^n new vectors with determined eigenaction. We consider principal series representations of G (induced from Borel of suitable characters of conductor p^n) and describe the 2-dimensional local newforms in these representations under the action of H.

In another work with Ramla Abdellatif, we describe the p-modular Iwahori-Hecke algebras (with trivial and quadratic) associated with G using generators and relations. We compute the center of these algebras and use this and the presentation to classify their finite dimensional simple modules, they are at most 2 dimensional. When the character is neither trivial nor quadratic, the p-modular Iwahori Hecke algebra turns out to be a polynomial algebra. In each of these cases, we compute the Iwahori-isotypical components of genuine principal series representations.

Current Status of Research Progress
Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

We plan to use the aforementiond results to compute local newforms in the automorphic representation of metaplectic SL_2(Q_p). We considered the case of irreducible principal series and will next consider the special and supercuspidals. We expect to obtain (partially) local newform theory of half integral weight for p odd. We have also done computations of subalgebra of level 2^n. We will return to this once we complete the odd p case.

On the p-modular Shimura correspondence work with Dr. Abdellatif, we not only recover and generalized Peskin’s results for arbitrary odd p but also classified the finite dimensional representations of Iwahori Hecke algebras (with character) and obtained the Iwahori invariant vectors of principal series representations.

Strategy for Future Research Activity

In the complex representation setting, we next plan to consider the special representations of the metaplectic SL_2(Q_p) and compute the associated local newforms. The next goal will be to study the supercuspidal representations. By Shimura-Waldspurger, we know the correspondence between representations of metaplectic SL_2 and that of PGL_2. Using this and our computation of local newforms we hope to obtain a local newform theory of half integral weight for p odd. As mentioned above, we also plan to complete our computations of subalgebra of level 2^n and hope to obtain local newforms for p=2 case.

In p-modular setting, having described the Iwahori Hecke algebra and the Iwahori module structures, our next goal is to study and describe the connection with the pro-p Iwahori Hecke algebra and their modules. On the representation theoretic side, the goal is to determine the irreducible smooth representations of metaplectic SL_2(Q_p) (given Peskin's work and our generalization, we are left to describe the mod p genuine supersingular representation). This required study of the category of right modules over the Iwahori-Hecke algebras aforementioned. We plan to compare our classification results with those obtained by Witthaus for metaplectic GL_2 and hope to obtain some first instance of functoriality in the p-modular setting.

Report

(6 results)
  • 2023 Research-status Report
  • 2022 Research-status Report
  • 2021 Research-status Report
  • 2020 Research-status Report
  • 2019 Research-status Report
  • 2018 Research-status Report
  • Research Products

    (23 results)

All 2024 2023 2022 2021 2020 2019 2018 Other

All Journal Article (7 results) (of which Int'l Joint Research: 3 results,  Peer Reviewed: 3 results) Presentation (13 results) (of which Invited: 9 results) Book (1 results) Remarks (1 results) Funded Workshop (1 results)

  • [Journal Article] A variant of the congruent number problem2024

    • Author(s)
      Jerome T Dimabayao, Soma Purkait
    • Journal Title

      Kyushu Journal of Mathematics (Accepted)

      Volume: Vol.78 no.2

    • Related Report
      2023 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] pi/4 Congruent number problem2022

    • Author(s)
      Soma Purkait
    • Journal Title

      WINJ2022 第15回数論女性の集まりと共に

      Volume: -

    • Related Report
      2022 Research-status Report
  • [Journal Article] Hecke Algebra of Level p^22021

    • Author(s)
      Soma Purkait
    • Journal Title

      WINJ14 第14回数論女性の集まりと共に

      Volume: - Pages: 69-79

    • Related Report
      2021 Research-status Report
  • [Journal Article] Newforms of half-integral weight: the minus space counterpart2019

    • Author(s)
      E.M. Baruch, S. Purkait
    • Journal Title

      Canadian Journal of Mathematics

      Volume: To appear

    • Related Report
      2018 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Newforms of half-integral weight: the minus space of S_(k+1/2) (Γ_0 (8M))2019

    • Author(s)
      E.M. Baruch, S. Purkait
    • Journal Title

      Israel Journal of Mathematics

      Volume: To appear

    • Related Report
      2018 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Newforms of half-integral weight2019

    • Author(s)
      S. Purkait
    • Journal Title

      RIMS Kokyuroku

      Volume: 2100 Pages: 109-120

    • Related Report
      2018 Research-status Report
  • [Journal Article] 3. On distinguishing representations of different conductor2018

    • Author(s)
      S. Purkait
    • Journal Title

      「第11回数論女性の集まり」報告集

      Volume: 11 Pages: 77-81

    • Related Report
      2018 Research-status Report
  • [Presentation] p-modular Iwahori-Hecke algebras and their simple modules for the p-adic metaplectic group SL_2(F)2023

    • Author(s)
      Ramla Abdellatif
    • Organizer
      京大数論合同セミナー
    • Related Report
      2023 Research-status Report
    • Invited
  • [Presentation] An irrational variant of the congruent number problem2023

    • Author(s)
      Jerome T Dimabayao
    • Organizer
      九大代数学セミナー
    • Related Report
      2023 Research-status Report
    • Invited
  • [Presentation] Pi/4 Congruent Number Problem2022

    • Author(s)
      Soma Purkait
    • Organizer
      WINJ2022 第15回数論女性の集まりと共に
    • Related Report
      2022 Research-status Report
  • [Presentation] A 2-adic Hecke algebra and its applications2022

    • Author(s)
      Moshe Baruch
    • Organizer
      Number Theory in Tokyo
    • Related Report
      2022 Research-status Report
    • Invited
  • [Presentation] An irrational variant of the congruent number problem2022

    • Author(s)
      Jerome Dimabayao
    • Organizer
      Number Theory in Tokyo
    • Related Report
      2022 Research-status Report
    • Invited
  • [Presentation] Hecke algebra of level p^22021

    • Author(s)
      Soma Purkait
    • Organizer
      第14回数論女性の集まり
    • Related Report
      2021 Research-status Report
  • [Presentation] Local Hecke algebras and Whittaker functions2021

    • Author(s)
      Soma Purkait
    • Organizer
      Modular forms: Conference in honour of Prof. B. Ramakrishnan’s 60th birthday
    • Related Report
      2021 Research-status Report
    • Invited
  • [Presentation] Hecke algebras, Whittaker functions and New space2020

    • Author(s)
      Soma Purkait
    • Organizer
      International Seminar on Automorphic Forms
    • Related Report
      2019 Research-status Report
    • Invited
  • [Presentation] Local Hecke algebra and minus space2019

    • Author(s)
      S. Purkait
    • Organizer
      Number theory conference, IMSc Chennai
    • Related Report
      2018 Research-status Report
    • Invited
  • [Presentation] New forms of half integral weight2019

    • Author(s)
      S. Purkait
    • Organizer
      International Conference on Number Theory, IISER TVM
    • Related Report
      2018 Research-status Report
    • Invited
  • [Presentation] Local Hecke algebras, newforms and new vectors2018

    • Author(s)
      S. Purkait
    • Organizer
      Automorphic forms on reductive groups and their covers: In honour of Solomon Friedberg", ETH Zurich.
    • Related Report
      2018 Research-status Report
  • [Presentation] Minus space of level 82018

    • Author(s)
      S. Purkait
    • Organizer
      Kanazawa Number theory Mini-Workshop 2018.
    • Related Report
      2018 Research-status Report
    • Invited
  • [Presentation] On distinguishing representations of different conductor2018

    • Author(s)
      S. Purkait
    • Organizer
      WINJ11 Workshop, Rikkyo University.
    • Related Report
      2018 Research-status Report
  • [Book] The Computational and Theoretical Aspects of Elliptic Curves (Chapter 6)2019

    • Author(s)
      Liang, Zhibin, Aribam, Chandrakant (Eds.)
    • Total Pages
      11
    • Publisher
      Springer
    • ISBN
      9789811366642
    • Related Report
      2019 Research-status Report
  • [Remarks] International conference "Number Theory in Tokyo"

    • URL

      https://sites.google.com/view/ntint/

    • Related Report
      2022 Research-status Report
  • [Funded Workshop] Number Theory in Tokyo2022

    • Related Report
      2022 Research-status Report

URL: 

Published: 2018-04-23   Modified: 2024-12-25  

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