An ideal gas undergoes a process maintaining relation between pressure ( $P$ ) and volume ( $V$ ) as $P=P_{\mathrm{o}}\left(1+\left(\frac{V_{\mathrm{o}}}{V}\right)^2\right)^{-1}$, where $\mathrm{P}_0$ and $\mathrm{V}_0$ are constants. If two samples A and B (two moles each) with initial volumes $\mathrm{V}_0$ and $3 \mathrm{~V}_0$ respectively undergo above mentioned process and attain same pressure, then the difference at the temperatures of these samples, $\mathrm{T}_{\mathrm{B}}-\mathrm{T}_{\mathrm{A}}$ (Initially) is $\_\_\_\_$ . ( $R=$ gas constant)