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314
bio website home.gwu.edu/~mparis
location Santa Fe, NM
age 45
visits member for 2 years, 10 months
seen Jun 26 at 2:19

Nuclear physics, theory


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
28
comment Neutrinos and anti-neutrinos in the Standard Model
You're right. It should have been "2) No.". Thanks.
Feb
27
comment Neutrinos and anti-neutrinos in the Standard Model
I mentioned this. Please reread the final sentence. I agree that it's somewhat cryptic.
Feb
27
answered Neutrinos and anti-neutrinos in the Standard Model
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."