Production of $P_c$ states in ${\Lambda }_b$ decays

Abstract

We develop a model for the production of the Pc states observed at LHCb in Lambdab - Jpsi p K- decays. With fewer parameters than other approaches, we obtain excellent fits to the Jpsi-p invariant mass spectrum, capturing both the prominent peaks, and broader features over the full range of invariant mass. A distinguishing feature of our model is that whereas Pc(4312), Pc(4380), and Pc(4440) are resonances with Sigmac*-D* constituents, the nature of Pc(4457) is quite different, and can be understood either as a Sigmac-D* threshold cusp, a Lambdac(2595)-D enhancement due to the triangle singularity, or a Lambdac(2595)-D resonance. We propose experimental measurements that can discriminate among these possibilities. Unlike in other models, our production mechanism respects isospin symmetry and the empirical dominance of colour-enhanced processes in weak decays, and additionally gives a natural explanation for the overall shape of the data. Our model is consistent with experimental constraints from photoproduction and Lambdab - Lambdac-D(*)0 K- decays and it does not imply the existence of partner states whose apparent absence in experiments is unexplained in other models.

51 pages, 13 figures. Additional discussion and results. Version to appear in PRD

References in corpus (16)

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• The hidden charm pentaquarks are the hidden color-octet $uud$ baryons?
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Cited by in corpus (7)

• 50 Years of Quantum Chromodynamics
• Emergence of molecular-type characteristic spectrum of hidden-charm pentaquark with strangeness embodied in the $P_{\psi s}^{\Lambda }(4338)$ and $P_{cs}(4459)$
• Hidden-charm pentaquark states in a mass splitting model
• $P_c$ states and their open-charm decays with the complex scaling method
• Towards modeling the short-range interactions of hidden/open charm pentaquark molecular states
• Tetraquark mass relations in quark and diquark models
• Observation of ${\Lambda }_b^0\to {\Lambda }_c^{+}{\bar{D}}^{(\ast )0}{K}^{-}$ and ${\Lambda }_b^0\to {\Lambda }_c^{+}{D}_s^{\ast -}$ decays