Extraction of ND scattering lengths from the Λb → π−pD0 decay and properties of the Σc(2800)+

Abstract

The isovector and isoscalar ND s-wave scattering lengths are extracted by fitting to the LHCb data of the pD0 invariant-mass distribution in the decay Λb→π−pD0, making use of the cusp effect at the nD+ threshold. The analysis is based on a coupled-channel nonrelativistic effective field theory. We find that the real part of the isovector ND scattering length is unnaturally large due to the existence of a near-threshold state with a mass around 2.8 GeV. The state is consistent with the Σc(2800)+ resonance observed at Belle. Our results suggest that it couples strongly to the ND channel in an s-wave, and that its quantum numbers are JP=1/2−. The strong cusp behavior at the nD+ threshold can be verified using updated LHCb data.

Keywords

• ND scattering lengths
• Charmed baryons