# W particle and beta decay

1. Sep 9, 2004

### Rothiemurchus

w particle and beta decay and muons

How many w particles,at any instant in time, are there in one cubic metre of a mass of radioactive nuclei which undergo beta decay?
And how fast do these w particles move on average?
How many w particles are,at any instant in time, in the neighbourhood of a muon that strikes the upper atmosphere of the Earth?

Last edited: Sep 9, 2004
2. Sep 9, 2004

### zefram_c

Short answer: None, unless some of those nuclei/muon have an energy greater than 80 GeV, in which case a real W might be produced (it decays away very quickly though).

Longer answer: you're probably thinking of virtual particles "constantly being emitted and re-absorbed" by the nuclei/muon. Since virtual states are not observable, this is not a physically meaningful question.

3. Sep 9, 2004

### misogynisticfeminist

How many particles are emitted in a radioactive nuclei undergoing beta decay?? Uhhhh, if I'm not wrong isn't it dependent on how radioactive it is, how many becquerels stuff like that? I don't think the rate of radioactivity is constant right?

btw, to zefram_c, are the W particles emitted by a quark during beta decay virtual or real?? Are if I'm not wrong W particles are pretty massive, is there something about the higgs mechanism which cause this mass? or is it something else?

4. Sep 9, 2004

### zefram_c

That's right, but the original question asked about W particles. I don't know how you define the rate (# decays/sec maybe), but the probability that a given nucleus decays per unit time is constant.
They cannot be real in the decay of an isolated particle. However, if a nucleus that has an energy great enough scatters off another nucleus, it can emit a real W in the process.
The Higgs mechanism is what generates the mass, yes. But the details of that should probably go in a different thread.

5. Sep 10, 2004

### marlon

In decay the W particles are virtual, yet as we all know they can become real when there is enough energy "around" that is used to give these virtual particles a legitimate reason to exist. Conservation of energy can be violated in QFT for a short while and this time period is determined by the Heisenberg-uncertainty principle between energy and time.

regards
marlon

and yes, the mass of the gauge bosons is acquired through interaction with the omnipresent Higgsfield after the spontanuous breakdown of symmetry of the QCD-vacuum (the U(1)-symmetry, right...)

:tongue2: