Arithmeticity of critical $L$-values for Hilbert-Siegel modular forms in the left half plane and $s = 1$

Abstract: For a cuspidal automorphic representation $π_f$ generated by a Hilbert-Siegel modular form $f$ and a Hecke character $μ$ with parallel signature, we show the arithmeticity of critical $L$-values of the standard $L$-function $L^S(s,π_f, μ)$ twisted by $μ$ in the left half plane. As a consequence, we show the arithmeticity at $s=1$ under the assumption that there exists a nonarchimedean place $v$ such that $π_v$ is unramified and $μ_v$ is ramified.