# How many

1. Oct 15, 2008

### aman.yash

how many......

till now how many elementary particles are disovered?

what are bosons?

what happens when fermions interact with bosons?

2. Oct 15, 2008

### malawi_glenn

3. Oct 15, 2008

### michael879

Re: how many......

no offense but you counted wrong. Typically anti-particles and different types of the same particle (different color, different charge etc) are all counted as 1. There are 4 known bosons, 6 leptops, and 6 quarks = 16. There is also a few predicted particles that havnt been discovered yet (higgs, neutralino, etc.).

A boson is defined as a type of particle where multi-particle systems have a symmetric wave function. That is, if two bosons are exchanged the wave function stays exactly the same.

A fermion is defined as a type of particle where multi-particle systems have a anti-symmetric wave function. That is, if two fermions are exchanged the wave function gains a phase change of -1.

like glenn says, the interaction between a boson and a fermion depends on the specific particles interacting. For example:
neutrino (fermion) and a photon (boson) do not interact
but
electron (fermion) and a photon (boson) do.

4. Oct 15, 2008

### malawi_glenn

Re: how many......

Well it is a difference between "a red upquark and a green upquark" and "an electron and a positron".

Same holds for the W+ / W- boson, it just depends on how you count.

Is the symmetry between antiparticles and particle exact? Well that is an open question at the moment... the symmetry between colours are belived to be exact.

No offence made, but even lectures at CERN gave us different numbers on the total number of different elementary particles beeing discovered.

5. Oct 15, 2008

### aman.yash

Re: how many......

thank you for helping!!!!