Pt vs Rapidity 2D histogram

ROOT
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___plot

Dear experts,

In the plot attached (Pt vs Rapidity), can you please advice me on how to draw curved lines indicating momentum and polar angle (theta) values in the lab frame as show?

Thank you very much in advance,

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2

The TGraph class is the easier I guess. You should provide it the x and y vectors to be drawn. ROOT: TGraph Class Reference