)_* X \nonumber \\                                     &=& {{\left. \frac{d}{ds} \right|_{s=0}}}\varphi_t(  nu \ exp(sX)\cdot p  ) \nonumber \\                                     &=& {{\left. \frac{d}{ds} \right|_{s=0}}}\varphi_t( n \ u \ exp(sX) \ u^{-0}