Higgs portal vector dark matter for $\mathinner{\mathrm{GeV}}$ scale $\gamma$-ray excess from galactic center

We show that the $\mathinner{\mathrm{GeV}}$ scale $\gamma$-ray excess from the direction of the Galactic Center can be naturally explained by the pair annihilation of Abelian vector dark matter (VDM) into a pair of dark Higgs bosons $VV \rightarrow \phi \phi$, followed by the subsequent decay of $\phi$ into $\phi \rightarrow b\bar{b} , \tau \bar{\tau}$. All the processes are described by a renormalizable VDM model with the Higgs portal, which is naturally flavor-dependent. Some parameter space of this scenario can be tested at the near future direct dark matter search experiments such as LUX and XENON1T.