This title appears in the Scientific Report : 2015 

How to reveal the exotic nature of the $P c ( 4450 )$
Guo, Feng-Kun (Corresponding author)
Meißner, Ulf-G. / Wang, Wei / Yang, Zhi
Theorie der Starken Wechselwirkung; IAS-4
Theorie der starken Wechselwirkung; IKP-3
Physical Review D Physical review / D, 92 92 (2015 2015) 7 7, S. 071502 071502
[S.l.] Soc. 2015
Journal Article
Symmetries and the Emergence of Structure in QCD
Computational Science and Mathematical Methods
Please use the identifier: in citations.
Please use the identifier: in citations.
The LHCb Collaboration announced two pentaquark-like structures in the $J/\psi p$ invariant mass distribution. We show that the current information on the narrow structure at 4.45 GeV is compatible with kinematical effects of the rescattering from $\chi_{c1} p$ to $J/\psi p$: First, it is located exactly at the $\chi_{c1} p$ threshold. Second, the mass of the four-star well-established $\Lambda(1890)$ is such that a leading Landau singularity from a triangle diagram can coincidentally appear at the $\chi_{c1} p$ threshold, and third, there is a narrow structure at the $\chi_{c1}\,p$ threshold but not at the $\chi_{c0} p$ and $\chi_{c2} p$ thresholds. In order to check whether that structure corresponds to a real exotic resonance, one has to measure the process $\Lambda_b^0\to K^-\chi_{c1} p$. If the $P_c(4450)$ structure exists in the $\chi_{c1} p$ invariant mass distribution as well, then the structure cannot be just a kinematical effect but is a real resonance, otherwise, one cannot conclude the $P_c(4450)$ to be another exotic hadron. In addition, it is also worthwhile to measure the decay $\Upsilon(1S)\to J/\psi p \bar p$: a narrow structure at 4.45 GeV but not at the $\chi_{c0} p$ and $\chi_{c2} p$ thresholds would exclude the possibility of a pure kinematical effect.