Tensor Charge of the Nucleon in Lattice QCD

First results of lattice QCD simulation on the nucleon tensor-charge $\delta q$ are presented. From the quenched QCD simulations with the Wilson quark action at $\beta =5.7$ on a 16${}^3\times$ 20 lattice and on a ${12}^3\times 20$ lattice, we find (i) the connected part $\delta q_{con\mathrm{.}}$ is determined with small statistical error, (ii) the disconnected part $\delta q_{dis\mathrm{.}}$, which violates the OZI rule, is consistent with zero, and (iii) the flavor-singlet tensor charge $ \delta \Sigma (\mu^2 = 2 {\rm GeV}^2) = \delta u + \delta d + \delta s$takes0.562(88)at$\beta=5.7$, which is in contrast with the flavor-singlet axial charge $\mathrm{\Delta }\mathrm{\Sigma }=0.1-0.3$.