Find two possible mechanisms for the decay p + + e by suitably relabelling

Find two possible mechanisms for the decay p → π⁺ + ν̅_e by suitably relabelling the lines in Figure 12.4(a) and (b). Check that the electric charge Q and the difference (B − L) are both conserved at the vertices in the resulting diagrams, using the values for the latter quantity deduced in Problem 12.2.

Figure 12.4(a) and (b) 

Data From Problem 12.2

Show that it is possible to assign values of (B − L) (B is the baryon number and L is the lepton number) to the X and Y bosons in such a way that B − L is conserved for all the fundamental vertices of Figures 12.2(c) and (d) and Figures 12.3. What are the values of B − L required?

Figure 12.2 (c) and (d) 

Figure 12.3