Solution

ID: past-exam-of-the-particle-physics-course-of-the-university-of-oxford/2017/3/c/solution

Restore the unit conversion in the phase,
Equivalently use mass units and energies in , with . The numerical conversion factor is
Thus
The familiar coefficient uses in metres and in MeV, or kilometres and GeV; it would be a factor of one thousand too small with the units requested here.[ref] The quoted differences with units are interpreted as squared-mass differences, despite the source's abbreviated notation.

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