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Critical values of $L$-functions of residual representations of $\mathrm{GL}_4$

Johannes Droschl

TL;DR

This work extends Gröbner–Raghuram-type rationality results for critical $L$-values from cohomological cuspidal representations to non-cuspidal discrete series of ${ m GL}_4$, by lifting from ${ m GL}'_2$ via the Jacquet–Langlands correspondence on a quaternion algebra. It uses Shalika models and zeta-integrals to express critical values as Shalika periods up to a rational multiple, under admissibility and cohomological hypotheses; the analysis hinges on a careful treatment of automorphic rational structures and twists by Hecke characters. The main contributions include (i) a framework for rational structures and Aut$(oldsymbol C)$-compatibility in the residual setting, (ii) a Shalika–period interpretation of critical values for ${ m GL}_4$-residual representations, and (iii) concrete algebraicity statements for twisted and untwisted half-integer critical values within the field ${f Q}(oldsymbol\\Pi',oldsymbol\\chi,oldsymbol\\eta)$. These results illuminate the arithmetic nature of special values of $L$-functions attached to residual automorphic representations and provide tools for explicit algebraicity computations via cohomology and periods.

Abstract

In this paper we prove rationality results of critical values for $L$-functions attached to representations in the residual spectrum of $\mathrm{GL}_4(\mathbb{A})$. We use the Jacquet-Langlands correspondence to describe their partial $L$-functions via cuspidal automorphic representations of the group $\mathrm{GL}_2'(\mathbb{A})$ over a quaternion algebra. Using ideas inspired by results of Grobner and Raghuram we are then able to compute the critical values as a Shalika period up to a rational multiple.

Critical values of $L$-functions of residual representations of $\mathrm{GL}_4$

TL;DR

This work extends Gröbner–Raghuram-type rationality results for critical -values from cohomological cuspidal representations to non-cuspidal discrete series of , by lifting from via the Jacquet–Langlands correspondence on a quaternion algebra. It uses Shalika models and zeta-integrals to express critical values as Shalika periods up to a rational multiple, under admissibility and cohomological hypotheses; the analysis hinges on a careful treatment of automorphic rational structures and twists by Hecke characters. The main contributions include (i) a framework for rational structures and Aut-compatibility in the residual setting, (ii) a Shalika–period interpretation of critical values for -residual representations, and (iii) concrete algebraicity statements for twisted and untwisted half-integer critical values within the field . These results illuminate the arithmetic nature of special values of -functions attached to residual automorphic representations and provide tools for explicit algebraicity computations via cohomology and periods.

Abstract

In this paper we prove rationality results of critical values for -functions attached to representations in the residual spectrum of . We use the Jacquet-Langlands correspondence to describe their partial -functions via cuspidal automorphic representations of the group over a quaternion algebra. Using ideas inspired by results of Grobner and Raghuram we are then able to compute the critical values as a Shalika period up to a rational multiple.
Paper Structure (26 sections, 49 theorems, 449 equations)

This paper contains 26 sections, 49 theorems, 449 equations.

Key Result

Theorem 1

Assume ${\mathbb{D}}$ is a quaternion division algebra and $\Pi'$ a cuspidal irreducible automorphic representation of ${\mathrm{GL}}'_{2}\left({\mathbb{A}}\right)$. If $\mathrm{JL}\left(\Pi'\right)$ is cuspidal and irreducible, the following assertions are equivalent. If $\mathrm{JL}\left(\Pi'\right)$ is not cuspidal, $\mathrm{JL}\left(\Pi'\right)=\mathrm{MW}(\Sigma,2)$ for some cuspidal irreduc

Theorems & Definitions (87)

  • Theorem 1: GanTakII
  • Theorem 2
  • Theorem 3: Bad,MoeWal
  • Theorem 4: GroRag2
  • Lemma 1
  • proof
  • Theorem 5: Sal
  • Lemma 2
  • proof
  • Proposition 1
  • ...and 77 more