# When K-mesons decay

1. Jan 12, 2005

### Kika

ok say a K- meson decays to... Oh i dont know say... A pion 0 and a beta+ and a... what is the third particle in the series. If it was to decay like this would u not need the third particle to have a charge of 2 (dont worry i know this is impossible... and by impossible i mean without doubly charged particles which is definately not the answer) to balance the equation.

Could this decay series be a typo or could it be valid...

If you have a site containing info on baryons decaying by releasing leptons it would also be a great help because the next two questons also pertain to these types of decays

After a few hours online I got no closer to an answer
In need of help!
Kika

2. Jan 12, 2005

### dextercioby

The decay should be something like that:

$$K^{-}\rightarrow \pi^{0} + e^{-} +\bar{\nu}_{e}$$

There are several reasons for considering this reaction.Actually they are called conservation laws.4-momentum,electric charge,spin,lepton number,isospin,color,...all of them must be conserved in elementary processes.

Daniel.

PS.Hopefully someone else will give a link where u could read more into it,though i still think you ought to read a good book.Aitchinson &Hey is a good one.

3. Jan 12, 2005

### Kika

Thanks for that.

Now all i need to know is why, but I'll try to work that out for myself.

Thanks again!

4. Jan 13, 2005

### Kika

ok I got it wrong turns out it was a K+ meson thus the whole "charge of 2" thing... little help here!

5. Jan 13, 2005

### Staff: Mentor

Well using Daniel's equation

$$K^{+}\rightarrow \pi^{0} + e^{+} + {\nu}_{e}$$

But this is only one of several possibilities of decay modes.

The most probable decay mode (perhaps Daniel may confirm) is $K^{+}\rightarrow \mu^+ + \nu_\mu$.

6. Jan 15, 2005

### nrqed

Yes, the decay $K^{+}\rightarrow \mu^+ + \nu_\mu$ is observed about 63.5% of the time.

The next most observed decay is to $\pi^+ \pi^0$ (about 21% of the time)

Then ther is to $\pi^+ \pi^- \pi^+$ (5.6%)

and then $\pi^0 e^+ \nu_e$ (4.8%)

and then $\pi^0 \mu^+ \nu_\mu$ (3.2%)

and so on. (source : Particle Properties data Booklet, but that's a very old edition (1992) so these numbers may have changed a bit)

Pat