22.

(a) From Eq. 38-47,

Q

=

−∆m c

2

= (m

Λ

0

− m

p

− m

π

−

)c

2

=

1115.6 MeV

− 938.3 MeV − 139.6 MeV = 37.7 MeV .

(b) We use the formula obtained in problem 11 (where it should be emphasized that E is used to mean

the rest energy, not the total energy):

K

p

=

1

2E

Λ

(E

Λ

− E

p

)

2

− E

2

π



=

(1115.6 MeV

− 938.3 MeV)

2

− (139.6 MeV)

2

2(1115.6 MeV)

= 5.35 MeV .

(c) By conservation of energy,

K

π

−

= Q

− K

p

= 37.7 MeV

− 5.35 MeV = 32.4 MeV .