8. 函数 $y=\sin \left(2 x+\varphi-\frac{\pi}{3}\right)(\phi \in R)$ 为偶函数, 则 $|\phi|$ 的最小值为
由已知, 得 $\varphi-\frac{\pi}{3}=\frac{\pi}{2}+k \pi(\mathrm{k} \in \mathrm{Z}), \therefore \varphi=\frac{5 \pi}{6}+k \pi(\mathrm{k} \in \mathrm{Z}), \therefore|\varphi|_{\text {min }}=\frac{\pi}{6}$.