Sketch the sixth-order Feynman diagram

Sketch the sixth-order Feynman diagram representing Delbruck scattering: r + r -> r+ r. (This process, the scattering of light by light, has no analog in classical electrodynamics.) This question is from the textbook 'Introduction to elementary particles' by David Griffiths.

'Introduction to Elementary Particles' by David Griffiths problems 2.6, 2.6, 2.8

This question is from the textbook 'Introduction to Elementary Particles' by David Griffiths Question No. is 2.6,7,8 of the picture. (See attached file for full problem description)

Radioactive decay

What determines whether a particular element will have alpha or beta decay? For example 238 4 234 U -----> He + Th 92 2 90 is always shown as having alpha decay in books is this always the case why does it not have beta decay? is one type of decay ie(alpha decay in this case) merely more likely to happen? if so can you calculate this?

Solve Schrodinger equation for a potential

Solve the schrodinger equation for the following pontential V(x) = INFINITY x< 0 = -V0 (v subscript zero) 0 a V0 (v subscript zero) is positive and solutions needed are for energies E>0 Do not attempt to normalize the wave function. Asume particles are incident from x = -INFINITY (negative infinity). Evaluate all undertemined Coeffifients in terms of a single coeffiecent

Proton velocity/speed of light

What is B, when B=v/c and it is for a 20MeV Proton?