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arXiv · 2601.20630

Searching for a $P_{cs}(4200)$ state in the $Λ_b\toϕη_cΛ$ reaction

Wen-Tao Lyu·Eulogio Oset
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Abstract

We propose the $Λ_b\toϕη_c Λ$ reaction to observe a $P_{cs}$ state around $4200$ MeV, predicted at lower masses than expected from comparison with the $P_c$ states, stemming as a consequence of the important role played by coupled channels in the $P_{cs}$ case, which does not appear in the $P_c$ case. That state decays to $η_c Λ$ with a width of about $200$ keV. The reaction is related to $Λ_b^0\toϕD_s^- Λ_c^+$, which has already been observed. We predict a branching fraction for $Λ_b\toϕP_{cs}(4200)$; $P_{cs}\toη_c Λ$ of the order of $10^{-5}$, which is within present capabilities of the LHCb collaboration. The observation of this state would bring valuable light on the nature of the $P_c$ and $P_{cs}$ states and the role played by coupled channels in hadron structure and hadron reactions.

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Wen-Tao Lyu, Eulogio Oset. 2026-05-05. Searching for a $P_{cs}(4200)$ state in the $Λ_b\toϕη_cΛ$ reaction. https://doi.org/10.1016/j.physletb.2026.140452

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