Peskin/schroeder RG flow diagram

[geoduck]

On page 403, diagram 12.1 (b) of Peskin and Schroeder, does anyone know why the coupling constant at first increases to the right, and then all of a sudden decreases to left until it reaches the fixed point zero?

According to equation 12.28, as b→0, the coupling decreases monotonically. So shouldn't the coupling always be decreasing?

 

[Vic Sandler]

I think it's just the perspective. The curves are supposed to be in the m^2 = 0 plane.