Form factors in semileptonic decay of D mesons

We study the vector, scalar and tensor form factors for the semileptonic process $D\rightarrow K$ by using lattice Quantum Chromodynamcs (QCD). Chiral lattice fermions are used in our study: overlap fermion for the valence quark and domain-wall fermion for the sea. The 2+1-flavor configurations are from the RBC-UKQCD Collaborations with an inverse lattice spacing $1/a=2.383(9)$ GeV. A modified $z$-expansion taking into account valence quark mass dependence is used to fit our numerical results of the form factors at a fixed pion mass $\sim360$ MeV in the sea. At the physical valence quark mass point we give the preliminary results $f_+(0)=f_0(0)=0.760(39)$ and $f_T(0)=0.733(50)$ with only statistical uncertainties. For $f_T$ the number is given in the $\overline{\rm MS}$ scheme at a scale of 2 GeV.