MarkWayne
Reputation
1,158
Next privilege 2,000 Rep.
 Oct 31 revised Normalization of the real Klein Gordon Field in Peskin and Schroeder chapter 2 added 10 characters in body Sep 4 awarded Yearling Aug 20 awarded Taxonomist Jun 22 comment Anomalous magnetic moment of electron You're trying to sound rigorous but you're just splitting hairs. Lorentz invariance itself is established experimentally. The initial point that your statement is folklore remains. We do obtain g=2 from the Pauli-Schrodinger equation without putting it in by hand when we recognize that $\mathbf{p}$ is not the appropriate operator for spin-1/2 particles. Jun 19 comment Anomalous magnetic moment of electron @ArnoldNeumaier: Yes. Of course, with this expression, carrying out the MS would give a coupling (from the first terms) that leads to the wrong rates for, say, (no spin-flip) atomic transitions. Jun 18 comment Anomalous magnetic moment of electron @ArnoldNeumaier: example? Jun 17 awarded Peer Pressure Jun 17 comment Anomalous magnetic moment of electron "g=2 comes from the Dirac equation, and is a relativistic effect. In the Pauli equation, it would have to be added by hand." This is folklore. Feynman pointed out (as Sakurai notes in Advanced QM, p.79, footnote) g=2 follows from the non-relativistic Schrodinger equation by writing the $H_0 = \mathbf{p}\cdot\mathbf{p}/(2m) = (\boldsymbol{\sigma}\cdot\mathbf{p})(\boldsymbol{\sigma}\cdot\mathbf{p})/(2m)$ and then making the minimal substitution $\mathbf{p}\to\mathbf{p}-e\mathbf{A}$. Apr 26 awarded Nice Answer Mar 3 comment Divergence of non conservative electric field I'm not sure how you gather that I "seem to be missing the point" of a trivial case of Gauss' law. Elaborate, if you want but please be specific. Sep 4 awarded Yearling Mar 28 awarded Enlightened Mar 28 awarded Nice Answer Mar 27 answered Angular Momentum Operator in Quantum Field Theory Mar 19 answered Internuclear Binding Force: Experimental geometric detail Feb 27 answered How to calculate critical temperature of the Ising model? Jan 24 comment Propagator and expectation value If you have the propagator then you know all of the eigenstates of the potential. See L. Brown's book, Quantum Field Theory, first chapter, section 1.5. Armed with this, you can devise a way to this calculation. Jan 24 comment Diagonalize a dot product with Pauli matrices You can use some notes I wrote for advanced high school or undergraduates to work through this problem yourself. A pdf version of the notes is here: public.lanl.gov/mparis/qmp.pdf -- And the relevant section with exercise problems start on page 32, section 5 of chapter 2. Nov 17 comment Baryon masses in Wetterich's new cosmology I have. You're still wrong. Nov 15 comment Baryon masses in Wetterich's new cosmology -1: From the abstract: "We discuss a cosmological model where the universe shrinks rather than expands during the radiation and matter dominated periods."