Odd parity bottom-flavored baryon resonances

TL;DR

This paper predicts and explains the properties of bottom-flavored baryon resonances, including their masses and quantum numbers, using a unitarized meson-baryon coupled-channel model that respects heavy-quark spin symmetry.

Contribution

It introduces a dynamical model that predicts bottom baryon resonances and their quantum numbers, aligning with recent experimental observations.

Findings

Resonances Lambda_b(5912) and Lambda*_b(5920) are heavy-quark spin symmetry partners.

Predicted bottom-strange baryon resonances at Xi_b(6035.4) and Xi_b(6043.3).

Resonances form a multiplet consistent with SU(3)-flavor and heavy-quark spin symmetry.

Abstract

The LHCb Collaboration has recently observed two narrow baryon resonances with beauty. Their masses and decay modes look consistent with the quark model orbitally excited states Lambda_b(5912) and Lambda*_b(5920), with quantum numbers J^P=1/2^- and 3/2^-, respectively. We predict the existence of these states within a unitarized meson-baryon coupled-channel dynamical model, which implements heavy-quark spin symmetry. Masses, quantum numbers and couplings of these resonances to the different meson-baryon channels are obtained. We find that the resonances Lambda^0_b(5912) and Lambda^0_b(5920) are heavy-quark spin symmetry partners, which naturally explains their approximate mass degeneracy. Corresponding bottom-strange baryon resonances are predicted at Xi_b(6035.4) (J^P=1/2^-) and Xi_b(6043.3) (J^P=3/2^-). The two Lambda_b and two Xi_b resonances complete a multiplet of SU(3)-flavor times heavy-quark spin symmetry.