Z° Isospin: Understanding T³=0 and Weak Isospin in Particle Physics

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Discussion Overview

The discussion revolves around the properties of the Z° boson in the context of weak isospin, specifically addressing whether the Z° retains a weak isospin value of T³=0 after mixing with other gauge bosons. Participants explore the implications of this mixing and the breaking of symmetry in the electroweak sector.

Discussion Character

  • Technical explanation, Debate/contested

Main Points Raised

  • One participant states that the Z° is a mixture of the iso-scalar B and the iso-triplet W°, questioning if it is valid to assert that the Z° has T³=0 due to symmetry breaking.
  • Another participant argues that since both the iso-scalar and the T³=0 component of the iso-triplet have T³=0, the resulting states after mixing (Z° and photon) should also have T³=0.
  • A third participant expresses agreement with the previous point but seeks confirmation on its correctness.
  • Another participant asserts that the Z° is in an eigenstate of charge (Q) and hypercharge (Y), suggesting it must also be in an eigenstate of T³.
  • A later reply simply affirms the previous statement.

Areas of Agreement / Disagreement

Participants generally agree on the assertion that the Z° retains T³=0 after mixing, but there is uncertainty regarding the correctness of this interpretation, indicating that the discussion remains somewhat unresolved.

Contextual Notes

The discussion does not clarify the implications of symmetry breaking on the weak isospin values or the specific conditions under which the mixing occurs, leaving some assumptions unaddressed.

tom.stoer
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Z° and weak isopsin

The Z° is a mixture of the B (iso-scalar) and the W° (iso-triplet with T³=0). Is it OK to say that the Z° still has T³=0? Or is this meaningless due to the breaking of the original SUwI(2) * UY(1) to Uem(1) and the mixing in the Z°?
 
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Since both the iso-scalar and the T3=0 component of the iso-triplet have T3=0, after mixing the resulting states (Z0 and photon) should still have T3=0 (I think).
 
I think so, too, but is this really correct?
 
The Z is in an eigenstate of Q, and in an eigenstate of Y, right? So it must be in an eigenstate of T3.
 
right
 

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