Talk:Weak isospin/Archive 1

Archive 1

Conservation law

There is also a weak isospin conservation law: all weak interactions must preserve the weak isospin.

But the spontaneously broken vacuum contains a charge condensate of Higgs bosons with nonzero weak isospin. If we take this charge condensate into account, weak isospin is still conserved, but it we don't, we can have a left handed electron (isospin I₃=-1/2) oscillating into a right handed electron (I₃=0). What "really" happens is the left-handed electron "emits" a Higgs boson (with I₃=-1/2) and turns into a right-handed electron, but the "emitted" Higgs boson enters the condensate and becomes undetectable because the number of Higgs boson in the charge condensate is undetermined. Maliz 20:22, 19 November 2006 (UTC)

Helicity or Chirality

Why does the article talk about the "helicity" of the left handed states but the "chirality" of the right handed states? --Gargletheape (talk) 16:42, 24 April 2008 (UTC)

Chirality is correct. Helicity is some kind of 'apparent chirality'. For details see Chirality, Helicity. --ErnstS 19:25, 29 February 2009 (CET)

Weak Isospin and Weak Hypercharge

Is it correct to state that weak isospin is a COMPONENT of weak hypercharge? (fourth sentence of the article) I think its those two TOGETHER that make up the electroweak SU(2)xU(1)gauge group, no?

Ambiguous Symbols

Symbol T is used with two different meanings: a) topness, b) weak isospin. Same problem for symbol B (Baryon Number/Bottomness was solved by denoting the latter as B' (also seen B^*). ==> Shouldn't topness be renamed the same way denoting it as T' ? -- As I₃ aka I_z is used for the (normal) isospin, weak isospin should only be denoted as T₃ alias T_z--ErnstS 19:35, 29 January 2009 (CET)

Another (may be better) way was to leave T as symbol for topness, to use I_W instead of T for weak isospin, and I_W3 (alias I_Wz) instead of T₃ (alias T_z) for its 3rd component (while I is used as symbol for Isospin, and I₃ aka I_z for the 3rd component of I). This resembles Y_w as symbol for weak hypercharge (while Y is used as symbol for Hypercharge)--ErnstS 22:15, 18 February 2009 (CET)

The problem, unfortunately, is that people use T/T_z for weak isospin. Also if you use I_W for weak isospin, then you'd have I_Wz or I_W3 for the "weak isospin projection" which is rather ugly. T prime ( T′ ) for topness would IMO be a much better choice than a house style I_W / I_Wz.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:24, 18 February 2009 (UTC)

I think the most common designation for I_Wz is I₃ and the W is implied by context. T looks ugly, IMO, and is confusing (again IMO). Any objections to standardisng on I rather than T?--Michael C. Price ^talk 09:23, 6 October 2009 (UTC)

Checking my textbooks, it looks like T₃ is the most common usage, not T_z. --Michael C. Price ^talk 22:24, 1 November 2009 (UTC)

Confusion between spin and isospin?

Shouldn't it be?

The symmetry associated with isospin is SU(2). This requires gauge bosons to transform between weak isospin charges: bosons W+, W− and W0. This implies that W bosons have a T = 1, with three different values of Tz.

Headbomb {^ταλκ_{κοντριβς} – WP Physics} 06:09, 2 February 2009 (UTC)

What about antiparticles?

The article says left-handed fermions have T = 1/2 and right-handed fermions have T = 0. What about antiparticles? Perhaps it should say left-handed fermions (and right-handed anti-fermions) have T = 1/2 and right-handed fermions (and left-handed anti-fermions) have T = 0.

See these class notes (PDF).

K.enevoldsen (talk) 19:51, 5 July 2009 (UTC)

Good of you to post that link, but it's gone dead. I suspect that you are right; my source is Schumm (2004). But I dare not wade in and make changes, because I am not a physicist.132.181.160.42 (talk) 04:09, 28 August 2009 (UTC)

Here are some more references and links defining the weak isospins of antiparticles.

"Why is B-L Conserved and Baryon Number Not Conserved in Unified Models of Quarks and Leptons", Harry J. Lipkin June, 1980, Argonne National Laboratory and Fermi National Accelerator Laboratory, Report Number: ANL-HEP-CP-80-44, OSTI ID: 6639172, PDF. Page 3: "In the standard models for quarks and leptons, all left-handed particles and right-handed antiparticles have weak isospin 1/2 and all right-handed particles and left-handed antiparticles have weak isospin zero."

"The Algebra of Grand Unified Theories", John Baez and John Huerta, March 11, 2010, Bulletin of the American Mathematical Society, Volume 47, Number 3, July 2010, PDF. Pages 500-501: "I3 [weak isospin] equals zero for right-handed particles, and +/- 1/2 for left-handed particles. ... Left-handed electron e-L I3 = -1/2. ... Right-handed electron e-R I3 = 0. [e- = electron] ... The antiparticle of a left-handed particle is right-handed, and the antiparticle of a right-handed particle is left-handed. The [weak] isospins also change sign. For example, I3(e+R) = +1/2 , while I3(e+L) = 0. [e+ = anti-electron]"

K.enevoldsen (talk) 23:31, 20 October 2010 (UTC)