Model-independent evidence for $J/\psi p$ contributions to $\Lambda_b^0\to J/\psi p K^-$ decays

TL;DR

This study provides strong, model-independent evidence that $J/ p$ contributions significantly influence $^0 o J/ p K^-$ decays, supporting the existence of pentaquark states.

Contribution

It offers the first model-independent evidence for $J/ p$ contributions in $^0$ decays, reinforcing prior model-dependent findings of pentaquark states.

Findings

More than 9 standard deviations evidence for $J/ p$ contributions.

Decays cannot be explained by $K^- p$ contributions alone.

Supports the existence of $P_c^+ o J/ p$ pentaquark states.

Abstract

The data sample of $\Lambda_b^0\to J/\psi p K^-$ decays acquired with the LHCb detector from 7 and 8~TeV $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$, is inspected for the presence of $J/\psi p$ or $J/\psi K^-$ contributions with minimal assumptions about $K^- p$ contributions. It is demonstrated at more than 9 standard deviations that $\Lambda_b^0\to J/\psi p K^-$ decays cannot be described with $K^- p$ contributions alone, and that $J/\psi p$ contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for $P_c^+\to J/\psi p$ charmonium-pentaquark states in the same data sample.