Could someone please explain electron (or any partical for that matter) spin in terms of quantum field theory. I am well aware of the classical interpretation: a rotating sphere inducing a magnetic field.
Don't tell me to go to wikipedia, I am looking for a first hand explaniation from another physicst.
2007-05-25 05:50:35 · 4 answers · asked by kennyk 4 in Science & Mathematics ➔ Physics
Spin is an intrinsic angular momentum of a particle (intrinsic as opposed to orbital, since a point particle can't have orbital angular momentum about itself). This spin is simply an additional degree of freedom for the particle, so in QFT, whereas spin-0 particles can be represented by a single field, spin-1/2 particles have to be represented by spinor fields.
2007-05-25 05:54:56 · answer #1 · answered by Anonymous · 1⤊ 0⤋
The following is more of a general quantum mechanical interpretation:
The electron has two types of angular momenta: orbital angular momentum (L) due to motion about the nucleus; and spin angular momentum (S). Unlike in classical mechanics, wherein spin angular momentum may be viewed as the integral sum of infinitesimal masses orbiting the center of mass of the particle in question, essentially identical to orbital angular momentum aside from naming convention, in quantum mechanics the spin is quite a distinct property intrinsic to a particle. Whereas the orbital angular momentum may be altered by changing the distance between the particle and the nucleus, spin angular momentum is immutable and distinct.
We note that the spin state of a particle is given by |s m>, where s is the spin and m = -s, -s +1, -s +2, ... , s - 1, s. For purposes of determining the spin states of combinations of two or more elementary particles, one may apply the Clebsch - Gordon tables to determine the possible values and the probability of each.
2007-05-25 13:44:50 · answer #2 · answered by riemannsurface2 1 · 0⤊ 0⤋
Spin results as a natural consequence of the Dirac equation of relativistic quantum mechanics. It turns out that Lorentz invariant solutions must have four components. Two become negligible at low velocities, so that in nonrelativistic QM (Shrodenger Eq.) only a two component "spinor" is left to consider. The spinor solution has angular momentum for fermions, with half integer spin.
2007-05-25 16:43:31 · answer #3 · answered by Dr. R 7 · 0⤊ 0⤋
Take a free lesson:
http://hyperphysics.phy-astr.gsu.edu/hbase/particles/parcon.html
2007-05-25 13:09:08 · answer #4 · answered by Anonymous · 0⤊ 0⤋