Recent content by gheremond

Consider a monoatomic 1-D chain of atoms (only acoustic branch). What happens with the inference of the dispersion curve through neutron scattering? In one dimension, conservation of momentum dictates $$ k'=k+K_s $$, if k_s is the phonon momentum vector and we only consider processes where a...

Whoa! I didn't expect it would get that deep! I would assume that things would be pretty clear for a theory like QED, which has be beaten into a pulp over decades of work. Great reference too! Thanks!

In QED, the Ward identities set Z_1=Z_2 and Z_1 - 1 = \left. {\frac{{d\Sigma \left( p \right)}}{{dp}}} \right|_{p = m} . This can be shown explicitly for the 1-loop calculations if one uses an on-shell subtraction scheme, where the renormalized mass and charge are identical to the...

Thanks for the reply! The parallel with complex conjugation in the Schroedinger equation indeed makes some sense. Yet it is not fully formally equivalent. It would be, provided you could define a current and density for the Dirac equation that is valid "component-wise", not as a sum of terms...

Consider the Dirac equation in the ordinary form in terms of a and \beta matrices i\frac{{\partial \psi }} {{\partial t}} = - i\vec a \cdot \vec \nabla \psi + m\beta \psi The matrices are hermitian, \vec a^\dag = \vec a,\beta ^\dag = \beta . Daggers denote hermitian...

Thanks for the reply. However, if you look on page 88, you will see that the definition for \delta ^{\alpha \beta } _{\mu \nu } = \delta ^\alpha _\mu \delta ^\beta _\nu - \delta ^\alpha _\nu \delta ^\beta _\mu according to MTW does not carry the 1/2! factor that you mention...

In Misner-Thorne-Wheeler Gravitation, Chapter 4, Page 92, Box 4.1, at section 4, there is a formula for the contraction of a p-form and a p-vector. Now, it states that the contraction of a p-form basis with a p-vector basis gives the antisymmetrizer symbol, \left\langle {\omega ^{i_1 } \wedge...