- #1
Einj
- 470
- 59
Hi everyone, I've been studying the so-called XYZ spectroscopy and the existence of possible 4-quark states.
The LHCb collaboration recently confirmed the existence of a particle called [itex]Z(4430)^-[/itex]. This particle is the unambiguous evidence for the existence of 4-quark states. From what I understood the reason is that this particle decays as [itex]Z(4430)^-\to \psi' \pi^-[/itex]. Since it decays in a [itex]c\bar c[/itex] it must contain such quarks as valence quarks. Moreover it is charged and therefore its minimal quark content can only be [itex]c\bar c d\bar u[/itex].
My question is: some time ago was also discovered another particle, the [itex]Z_c(3900)^+[/itex] decaying in [itex]J/\psi \pi^+[/itex]. Why this is not considered as an evidence for 4-quark states? It seems to me that it follows the same criteria as the [itex]Z(4430)^-[/itex].
Does anyone know something about it?
Thanks
The LHCb collaboration recently confirmed the existence of a particle called [itex]Z(4430)^-[/itex]. This particle is the unambiguous evidence for the existence of 4-quark states. From what I understood the reason is that this particle decays as [itex]Z(4430)^-\to \psi' \pi^-[/itex]. Since it decays in a [itex]c\bar c[/itex] it must contain such quarks as valence quarks. Moreover it is charged and therefore its minimal quark content can only be [itex]c\bar c d\bar u[/itex].
My question is: some time ago was also discovered another particle, the [itex]Z_c(3900)^+[/itex] decaying in [itex]J/\psi \pi^+[/itex]. Why this is not considered as an evidence for 4-quark states? It seems to me that it follows the same criteria as the [itex]Z(4430)^-[/itex].
Does anyone know something about it?
Thanks