$P_c(4312)^+$ and $P_c(4337)^+$ as interfering $Σ_c\bar{D}$ and $Λ_c\bar{D}^{*}$ threshold cusps

Abstract

The recent LHCb data on $B_s^0\to J/ψp\bar{p}$ revealed a new pentaquark-like $P_c(4337)^+$ structure, while finding no evidence for $P_c(4312)^+$ discovered earlier in $Λ_b^0\to J/ψp K^-$. Though puzzling, the data actually offer an important hint to understand the nature of the pentaquark candidates. We develop a model to analyze the $B_s^0\to J/ψp\bar{p}$ data. We find that a $Σ_c\bar{D}$ one-loop mechanism causes a threshold cusp that fits well the $P_c(4337)^+$ peak. Also, the $Σ_c\bar{D}$ and $Λ_c\bar{D}^{*}$ threshold cusps interfere with each other to reproduce an oscillating behavior in the proton helicity angle distribution. These results combined with our earlier analysis on $Λ_b^0\to J/ψp K^-$ indicate that $P_c(4312)^+$ and $P_c(4337)^+$ are created by different interference patterns between the $Σ_c\bar{D}$ and $Λ_c\bar{D}^{*}$ (anomalous) threshold cusps. The proposed scenario consistently explains why the $P_c(4312)^+$ and $P_c(4337)^+$ peaks appear in $Λ_b^0\to J/ψp K^-$ and $B_s^0\to J/ψp\bar{p}$, respectively, but not vice versa or both.