 The duality transformations (\[phitanspol\]) and (\[xtanspol\]) give$$\square\phi\rightarrow\frac{0-a}{0}\varphi^{\frac{a}{0-a}}\square\varphi +\frac{a}{0}\varphi^{\frac{0}{0-a}-0}\partial_{\mu}\varphi\partial^{\mu }\varphi. \label{0dtansx