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On infinitesimal $\boldsymbol { \tau }$-isospectrality of locally symmetric spaces

Published online by Cambridge University Press:  09 January 2025

Chandrasheel Bhagwat*
Affiliation:
Department of Mathematics, Indian Institute of Science Education and Research, Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India e-mail: cbhagwat@iiserpune.ac.in
Kaustabh Mondal
Affiliation:
Department of Mathematics, Indian Institute of Science Education and Research, Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India e-mail: cbhagwat@iiserpune.ac.in
Gunja Sachdeva
Affiliation:
Department of Mathematics, BITS Pilani, K.K. Birla Goa Campus, Zuarinagar, Goa 403726, India e-mail: gunjas@goa.bits-pilani.ac.in

Abstract

Let $(\tau , V_{\tau })$ be a finite dimensional representation of a maximal compact subgroup K of a connected non-compact semisimple Lie group G, and let $\Gamma $ be a uniform torsion-free lattice in G. We obtain an infinitesimal version of the celebrated Matsushima–Murakami formula, which relates the dimension of the space of automorphic forms associated to $\tau $ and multiplicities of irreducible $\tau ^\vee $-spherical spectra in $L^2(\Gamma \backslash G)$. This result gives a promising tool to study the joint spectra of all central operators on the homogenous bundle associated to the locally symmetric space and hence its infinitesimal $\tau $-isospectrality. Along with this, we prove that the almost equality of $\tau $-spherical spectra of two lattices assures the equality of their $\tau $-spherical spectra.

Type
Article
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Canadian Mathematical Society

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Footnotes

K. Mondal thanks Prime Minister Research Fellowship (PMRF) Govt. of India for supporting this work partially. G. Sachdeva’s research is supported by Department of Science Technology-Science and Engineering Research Board, Govt. of India POWER Grant [SPG/2022/001738].

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