Peaks within peaks and the possible two-peak structure of the Pc(4457): The effective field theory perspective

The LHCb pentaquarks-the P-c(4312), P-c(4440), and P-c(4457)-have been theorized to be Sigma(c)(D) over bar and Sigma(c)(D) over bar* S-wave molecules. Here, we explore the possibility that two of these pentaquarks-the P-c(4440) and P-c(4457)-contain in addition a Lambda(c)(2595)(D) over bar component in the P-wave. We will analyze the effects of this extra channel within two effective field theories: the first one will be a standard contact-range effective field theory, and the second one will include the nondiagonal pion dynamics connecting the Sigma(c)(D) over bar* and Lambda(c)(2595)(D) over bar channels, which happens to be unusually long ranged. The impact of the coupled-channel dynamics between the Sigma(c)(D) over bar* and Lambda(c)(2595)(D) over bar components is modest at best for the P-c(4440) and P-c(4457), which will remain predominantly Sigma(c)(D) over bar* molecules. However, if the quantum numbers of the P-c(4457) are J(P) = 1/2(-), the coupled-channel dynamics is likely to induce the binding of a Lambda(2595)(D) over bar S-wave molecule (coupled to Sigma(c)(D) over bar* in the P-wave) with J(P) = 1/2(+) and a mass similar to the P-c(4457). If this is the case, the P-c(4457) could actually be a double peak containing two different pentaquark states.