I What Are Tetraquarks and Why Are They Important?

[Kevin McHugh]

I just heard of these, can somebody explain what they are, how they were discovered, and the implications of their existence?

 

[ZapperZ]

Have you read this:

https://www.physicsforums.com/threads/fermilab-announces-new-tetraquark-state.859379/ ?

Zz.

 

[mfb]

Or better this from LHCb for a proper analysis (different state).

 

[Kevin McHugh]

Thanks ZZ, I had not seen that. The DZero link was very informative.

 

[Jimtaff]

I understand that these exotic particles are termed X Y and Z, and that the Y(4140) was recently renamed X(4140) by the Particle Data Group . Can someone explain the difference between X Y and Z please?

 

[mfb]

This paper with figure 2 would suggest Z for charged states, X for C even and Y for C odd states, but I don't know if that naming scheme is used universally, especially as these slides include a neutral Z (slide 11).