# Weak angle coupling constant

1. Dec 22, 2009

### enotstrebor

You still have not answered the question; What are the two forces of the weak angle coupling constant?

We have spin and charge as known forces. If you can not specifically identify spin or charge as one of the two forces involved in the weak coupling constant than for all you know there could be two new forces that couple together?

Where is Vanadium 50. May be he can answer how the the measured V-A theory $$g_v$$ and $$g_A$$ weak angle values are identified to be either charge $$g_v$$ and the other force of the weak coupling $$g_A$$ or as the other force of the weak coupling $$g_v$$ and spin $$g_A$$?

Last edited: Dec 23, 2009
2. Dec 23, 2009

### ansgar

The electric charge e (and thus the fine structure constant) is defined as:

$$e = \dfrac{g\,g' }{\sqrt{g^2 + {g'}^2}}$$

where g' , g are the U(1)_Y and SU(2)_L coupling constants respectively. Recall that the symmetry is BROKEN from SU(2)_L x U(1)_Y to U(1)_em so one can not call g and g' as "coupling constants of a force".

3. Dec 23, 2009

### arivero

I can not see the problem. The result of the failure of symmetry is a short-range force instead of a long range one, but still a force.

4. Dec 23, 2009

### ansgar

So the coupling constant of the "weak" force is?

5. Dec 23, 2009

### arivero

$$G_F$$

OK I think I see some point. We start we two coupling constants g g' AND a mass scale (the vacuum expected value of of the higgs field). So three quantities. But the historic experimental theory used only two coupling constants, $e$ and $G_F$.

Of course the answer is that $G_F$ is the coupling constant of the "charged weak force", related to the W particle, ant then we have another coupling constant for the "neutral weak force", related to the Z. Neutral currents were first predicted and only discovered later, so there is not a trace of this constant in the textbooks, it is produced from the other, using the Weinberg angle.

6. Dec 23, 2009

### ansgar

exactly arivero :)

7. Dec 24, 2009

### arivero

Another issue is symmetry restoration. For simplicity, and even again the OP, lets put $M_W=M_Z$. It is OK to have $e=0$. Now lets move $$M_W,M_Z\to 0$$. The couplings g and g' should emerge as couplings of two long-range forces, but it is not obvious from the empirical lagrangian.

8. Dec 24, 2009

### enotstrebor

Can no one answer this question???

9. Dec 24, 2009

Staff Emeritus
Your question is so riddled with inaccuracies, I doubt anyone can answer it. "We have spin and charge as known forces" indeed.

"Miss Vito, what would the correct ignition timing be on a 1955 Bel Air Chevrolet, with a 327 cubic-inch engine and a four-barrel carburetor?"

10. Dec 24, 2009

### enotstrebor

Since you choose not to enlighten but to vilify, I will make it simple for you, just answer the first line, i.e.

What are the two forces involved in the weak angle coupling constant?

Last edited: Dec 24, 2009
11. Dec 25, 2009