Roper-like resonances with various flavor contents and their two-pion emission decays
Ahmad Jafar Arifi, Hideko Nagahiro, Atsushi Hosaka, K. Tanida
Abstract
We study the three-body decay of the newly observed bottom baryon ${\mathrm{\ensuremath{\Lambda}}}_{b}^{*}(6072)$ by LHCb; ${\mathrm{\ensuremath{\Lambda}}}_{b}^{*}(6072)\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\pi}\ensuremath{\pi}$. Its mass about 500 MeV above the ground state ${\mathrm{\ensuremath{\Lambda}}}_{b}$ and a broad width imply that the state could be an analogue of the Roper resonance of the nucleon $N(1440)$. In terms of sequential processes going through ${\mathrm{\ensuremath{\Sigma}}}_{b}$ and ${\mathrm{\ensuremath{\Sigma}}}_{b}^{*}$, we find that the observed invariant mass distribution is reproduced assuming its spin and parity ${J}^{P}=1/{2}^{+}$. We discuss that the ratio of the two sequential processes and angular correlation of two pions are useful for the determination of spin and parity. We suggest further studies for the Roper resonance analogue in various flavor contents, raising an interesting and important question in baryon spectroscopy.