How to reveal the exotic nature of the P c (4450)

By F. Guo, U. Meissner, Wei Wang, Zhi Yang. 2015

244 citations recorded by the source corpus.

The LHCb Collaboration announced two pentaquark-like structures in the J/ψp 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 χc1p to J/ψp: First, it is located exactly at the χc1p threshold. Second, the mass of the four-star well-established Λ(1890) is such that a leading Landau singularity from a triangle diagram can coincidentally appear at the χc1p threshold, and third, there is a narrow structure at the χc1p threshold but not at the χc0p and χc2p thresholds. In order to check whether that structure corresponds to a real exotic resonance, one can measure the process Λb0→K-χc1p. If the Pc(4450) structure exists in the χc1p invariant mass distribution as well, then the structure cannot be just a kinematical effect but is a real resonance; otherwise, one cannot conclude that Pc(4450) is another exotic hadron. In addition, it is also worthwhile to measure the decay ϒ(1S)→J/ψpp¯: a narrow structure at 4.45 GeV but not at the χc0p and χc2p thresholds would exclude the possibility of a pure kinematical effect.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/c100472004797e409170cc763c1eab71b7449423

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Citations in the corpus

Observation of $J/\psi p$ Resonances Consistent with Pentaquark States in $\Lambda_b^0 \to J/\psi K^- p$ Decays (2015, background): “in Λ 0 b → χc1Kp, as this would rule out some rescattering models [86], while observing a deficit at the Pc(4450) mass in mχc1p would confirm them.”
Opportunities in Flavour Physics at the HL-LHC and HE-LHC (2018, background): “There are ways to distinguish triangle singularities from real resonances: i) quantum numbers, since triangle singularities produce narrow peaks only for S-wave couplings; ii) the near-threshold χc1p distribution for the process Λb → χc1pK, since a triangle singularity would not lead to a near-thres”
Multiquark States (2017, background): “via the so-called triangle anomaly, must happen in an S-wave to be pronounced, thus cannot account for spin 5/2 either [171, 172, 43].”
Hadronic molecules (2017, background): “(Guo et al., 2015b) where strong support is presented that at least some of the signals indeed refer to S-matrix poles.”
Physics case for an LHCb Upgrade II - Opportunities in flavour physics, and beyond, in the HL-LHC era (2018, unknown): “P+ c → χc1,2(→ J/ψγ)p) by amplitude analyses of Λb→ χc1,2pK− decays [480,481].”
Multiquark Resonances (2016, background): “The molecular models can describe the narrow state, either as a D̄Σc molecule [397], or as a χc1 p molecule [224], but cannot at the same time describe the broader state, or with opposite parity to the narrow one.”
The XYZ states: Experimental and theoretical status and perspectives (2019, background): “Triangle singularities might play an important role in different decays of vector mesons [341, 342, 796], and might explain the signal of the Zc(4430) [595, 797, 798] or the narrow pentaquark signal [799, 800].”