Guo, FK (reprint author), Chinese Acad Sci, Inst Theoret Phys, State Key Lab Theoret Phys, Beijing 100190, Peoples R China.
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 can measure the process Lambda(0)(b) -> 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 that P-c(4450) is another exotic hadron. In addition, it is also worthwhile to measure the decay Upsilon(1S) -> J/psi p (p) over bar: 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.
; NSFC [11261130311, 11165005, 11575110]
; Chinese Academy of Sciences (CAS) President's International Fellowship Initiative (PIFI) [2015VMA076]
; Shanghai Natural Science Foundation [11DZ2260700, 15ZR1423100]
; Open Project Program of State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, China [Y5KF111CJ1]
; Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry