Spin triplet superconductivity with line nodes in Sr2RuO4

Several possible odd-parity states are listed up group-theoretically and examined in light of recent experiments on Sr${}_2$RuO${}_4$. Those include some of the $f$-wave pairing states, ${\mib d}({\mib k})\propto{\hat{\mib z}} k_xk_y(k_x + {\rm i}k_y)$and${\hat{\mib z}} (k_x^2-k_y^2)(k_x + {\rm i}k_y)$andother${\hat{\mib z}} (k_x + {\rm i}k_y)\cos ck_z$($c$isthe$c$-axis lattice constant) as most plausible candidates. These are time-reversal symmetry broken states and have line nodes running either vertically (the former two) or horizontally (the latter), consistent with experiments. Characterizations of these states and other possibilities are given.