w demonstrate that

Li

$,$ Aj

PB $=\backslash$epsi ijkAk $,$

Ai

$,$ Aj

PB $=$

$2$

m

p

$2$

$2$m

$$

$\backslash$alpha

r

$\backslash$epsi ijkLk $,$

where Ai denotes the ith component of the Laplace$-$Runge$-$Lenz vector

A$=$

$1$

m

$$p $\backslash$times L$\backslash$alpha

$$r

r

$($Ai$),\backslash$alpha $=$ const $.$