For which subatomic particles do we have empirical evidence?

[murshid_islam]

I have two questions: which subatomic particles do we have empirical evidence for? And which are postulated but never been detected or doesn't have any evidence yet.

Thanks in advance.

 

[phyzguy]

I'd say we have mountains of empirical evidence for all of the particles of the standard model except the Higg's boson and the graviton.

 

[jtbell]

See the data collection of the Particle Data Group.

 

[Kevin_Axion]

Here is a list of Particles discovered and ones that are hypothetical but are predicted by Superstring Theory, and various other GUTs: http://en.wikipedia.org/wiki/List_of_particles.

 

[murshid_islam]

Thanks a lot for your help, everyone.

 

[murshid_islam]

One more question: Are the ideas that "Higgs boson exists" or "supersymmetry is a symmetry of nature" falsifiable even in principle?

 

[Kevin_Axion]

Yes, if we don't find the Higgs Boson in it's expected energy range also with Supersymmetry. But one can always extend the energy levels on Supersymmetry.

 

[murshid_islam]

Yes, if we don't find the Higgs Boson in it's expected energy range also with Supersymmetry. But one can always extend the energy levels on Supersymmetry.

What is the expected energy range for Higgs boson? I didn't really understand how "supersymmetry is a symmetry of nature" is falsifiable. Sorry, I must sounds pretty dumb. But these are new stuff for me.

 

[Kevin_Axion]

No, you don't sound dumb, you sound curious. The expected range for the Higgs Boson is between 115-185 GeV. An electro volt (eV) is the amount of energy an electron gains when accelerated through an electric potential difference of 1 volt = [tex] 1.602 x 10^{-19} J [/tex]. Supersymmetry is a symmetry of nature because it states that each fermion has a corresponding boson that differs by half a unit of spin and since it is a broken symmetry they are much more massive.

 

[murshid_islam]

Supersymmetry is a symmetry of nature because it states that each fermion has a corresponding boson that differs by half a unit of spin and since it is a broken symmetry they are much more massive.

If supersymmetry is false, how can we actually falsify it?

 

[Kevin_Axion]

It isn't false, falsifiable means it can be proven wrong through experiment. We are stll looking for Supersymmetry.

 

[murshid_islam]

It isn't false, falsifiable means it can be proven wrong through experiment.

Oh yes, I know that. I just wanted to know that just in case it is false, what experiment would prove it wrong.

 

[Kevin_Axion]

The LHC but you can always extend the mass of supersymmetric particles as to save them from falsification.

 

[murshid_islam]

The LHC but you can always extend the mass of supersymmetric particles as to save them from falsification.

What exactly did you mean by "extend the mass"?

 

[Kevin_Axion]

I mean the theorists can say "Well, the Supersymmetric Particles can be much more massive than what the energies can probe at the LHC."

 

[murshid_islam]

I mean the theorists can say "Well, the Supersymmetric Particles can be much more massive than what the energies can probe at the LHC."

Can the same thing be said about Higgs boson? Why or why not?

 

[Kevin_Axion]

Possibly, but I think there is an upper-limit on the mass of the Higgs boson while supersmmetric particles don't.