The t quantity is known as the square of the 4-momentum transfer
[math]\displaystyle{ t \equiv \left({\mathbf P_1^*}- {\mathbf P_1^{'*}}\right)^2=\left({\mathbf P_2^{*}}- {\mathbf P_2^{'*}}\right)^2 }[/math]
temp
[math]\displaystyle{ {\mathbf P_1^{2}}+ {\mathbf P_1^{'2}}-2 {\mathbf P_1} {\mathbf P_1^{'}} }[/math]
[math]\displaystyle{ 2m^2-2E_1E_1^'+2 p_1 p_1^' }[/math]
[math]\displaystyle{ }[/math]
[math]\displaystyle{ \textbf{\underline{Navigation}} }[/math]
[math]\displaystyle{ \vartriangleleft }[/math]
[math]\displaystyle{ \triangle }[/math]
[math]\displaystyle{ \vartriangleright }[/math]