The $p$-adic constant for mock modular forms associated to CM forms II

Abstract

For a normalized newform $g \in S_{k}(\Gamma_{0}(N))$ with complex multiplication by an imaginary quadratic field $K$, there is a mock modular form $F^{+}$ corresponding to $g$. K. Bringmann et al. modified $F^{+}$ in order to obtain a $p$-adic modular form by a certain $p$-adic constant $\alpha_{g}$. In addition, they showed that if $p$ is split in $\mathcal{O}_{K}$ and $p \nmid N$, then $\alpha_{g}=0$. On the other hand, the author showed that $\alpha_{g}$ is a $p$-adic unit for an inert prime $p$ satisfying that $p\nmid 2N$ when $\dim_{\mathbb{C}} S_{k}(\Gamma_{0}(N))=1$. In this paper, under mild condition, we determine the $p$-adic valuation of $\alpha_{g}$ for an inert prime $p$ and a general CM form $g$ of weight $2$ with rational Fourier coefficients.