See formula (39) : https://www.scielo.br/j/rbef/a/wh9hgMSRTJzvws8ZxzL8NNp/?format=pdf&lang=en
with :$\beta= tanh(\varphi)\;\;,\gamma=cosh(\varphi)\;\;, \beta\gamma = sinh(\varphi)$
https://en.wikipedia.org/wiki/Lorentz_transformation
we have:
$x'^{+}=\gamma(x^{+}-\beta x^{+})$
$ x'^{-}=\gamma(x^{-}-\beta x^{-}) $$ x'^{-}=\gamma(x^{-}+\beta x^{-}) $