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A note on a classical relative trace formula

Zhining Wei

TL;DR

This note presents a classical derivation of a relative trace formula for holomorphic cusp forms on $\mathrm{SL}_2(\mathbb{Z})$, yielding a closed formula for the eigenvalue-weighted second moment of central $L$-values. It decomposes the trace into spectral and geometric sides, with explicit expressions for singular and regular orbital integrals and a regularization that handles divergences, ultimately matching Kuznetsov’s preprint (and Iwaniec–Sarnak). The main result expresses the weighted second moment as $M_2(n;s_1,s_2)+E(n;s_1,s_2)$, with a detailed breakdown of terms from the geometric side and their analytic continuations, and a corollary at $(s_1,s_2)=(0,0)$. The approach combines classical kernel methods with hypergeometric representations and divisor arithmetic to produce explicit, computable terms, reinforcing connections to the Kuznetsov framework and related trace-formula techniques.

Abstract

In this note, we derive a relative trace formula (RTF) using classical methods. We obtain a closed formula for the second moment of the central values of holomorphic cusp forms, a result originally established in Kuznetsov's preprint.

A note on a classical relative trace formula

TL;DR

This note presents a classical derivation of a relative trace formula for holomorphic cusp forms on , yielding a closed formula for the eigenvalue-weighted second moment of central -values. It decomposes the trace into spectral and geometric sides, with explicit expressions for singular and regular orbital integrals and a regularization that handles divergences, ultimately matching Kuznetsov’s preprint (and Iwaniec–Sarnak). The main result expresses the weighted second moment as , with a detailed breakdown of terms from the geometric side and their analytic continuations, and a corollary at . The approach combines classical kernel methods with hypergeometric representations and divisor arithmetic to produce explicit, computable terms, reinforcing connections to the Kuznetsov framework and related trace-formula techniques.

Abstract

In this note, we derive a relative trace formula (RTF) using classical methods. We obtain a closed formula for the second moment of the central values of holomorphic cusp forms, a result originally established in Kuznetsov's preprint.

Paper Structure

This paper contains 19 sections, 10 theorems, 117 equations.

Key Result

Theorem A

(Kuznetsov, preprint $1994$) Assume that $\textbf{s}=(s_1,s_2)$ is in the region: and $s_1-s_2$ is not an integer. Then where and Here: Moreover, $(s_1,s_2)=(0,0)$ is a removable singularity.

Theorems & Definitions (23)

  • Theorem A
  • Remark 2.1
  • Lemma 2.2
  • proof
  • Proposition 3.1
  • proof
  • Proposition 3.2
  • proof
  • Proposition 3.3
  • proof
  • ...and 13 more