# Do colliders observe mass first-hand?

1. Nov 10, 2005

### jhe1984

Are all of the characteristics of particles currently confirmed by tests?

For instance, while I understand that certain particles are prescribed certain masses - and that these particles can be observed in cloud chambers, etc - but is the mass itself confirmed in the lab? By what process?

Also - and this is probably worthy of another thread - how will the graviton (the actual particle, not the phenomenon of g waves or gravity) be "discovered" in the lab? Will this happen soon or is the graviton still very speculative currently?

Thanks

2. Nov 10, 2005

### Pengwuino

What do you mean "how will it be discovered"? If it doesn't exist, it's not going to be discovered.... But if it does, of course, it will be hopefully.

3. Nov 10, 2005

### Staff: Mentor

Experiments and theoretical models have been going concurrently. As colliders have achieved higher energies, more particles have been discovered.

Take a look in the thread - Elementary Particles Presented - https://www.physicsforums.com/showthread.php?t=43685

4. Nov 11, 2005

### Intuitive

Doesn't Gravity act like a omni-directional Monofield in some sence?

5. Nov 11, 2005

### Staff: Mentor

In particle-physics experiments one determines the mass of a particle by measuring energy and momentum of the particles in an interaction that includes the particle in question, and applying conservation of energy and momentum, and the relationship

$$E^2 = (pc)^2 + (m_0 c^2)^2$$

New particles have often first shown up as peaks in a histogram of $E^2 - (pc)^2$ where E and p are the total energy and momentum of the outgoing particles after an interaction, indicating that a particle with the corresponding mass was an "intermediate" particle in the reaction.

6. Nov 16, 2005

### ahrkron

Staff Emeritus
Here is an example of the distribution mentioned by jtbell. This is from a published CDF result, showing the mass of a B-meson, reconstructed from its observable decay products.

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7. Nov 16, 2005

### marlon

With all due respect, but allow me to contemplate on this raethorical question : "Do i understand myself, the words i have just written down ?"

regards
marlon