Interpretation of the newly observed Λb(6146) and Λb(6152

Abstract

The strong decays of the low-lying λ-mode Λ b (1D, 2S ) and Σ b (2S ) states are studied in a chiral quark model. We find that: (i) the newly observed Λ b (6146/6152) resonances in the Λ b π + π − spectrum by the LHCb Collaboration might be explained with the λ-mode Λ b (1D) states in the quark model. It should be emphasized that whether the structure in the Λ b π + π − spectrum correspond to two states or one state should be further clarified with more observations in future experiments. (ii) The Λ b (2S ) |J P = 1 2 + , 0 state mainly decays into Σ * b π channel, which may be an ideal channel for searching for this Λ b (2S ) state in future experiments. (iii) The Σ b (2S ) |J P = 1 2 + , 1 and |J P = 3 2 + , 1 dominantly decay into Λ b π with Γ ≃ 3.82 MeV and Γ ≃ 4.72 MeV, respectively. PACS numbers:

Observation of a new baryon state in the $$ {\Lambda}_{\mathrm{b}}^0{\pi}^{+}{\pi}^{-} $$ mass spectrum

“…[ of narrow states, Λ b (6146) 0 and Λ b (6152) 0 , was also observed by LHCb collaboration [10]. The measured masses and widths of these states are compatible with the expectations for the Λ b (1D) 0 doublet [11][12][13][14]. Recently, the CMS collaboration reported an evidence for a broad excess of events in the Λ 0 b π + π − mass spectrum in the region of 6040 − 6100 MeV corresponding to a statistical significance of four standard deviations [15].…”

Possible interpretation of the newly observed $$\Omega _b$$ states

“…In this work we study the strong decay properties with the chiral quark model. This model has been successfully applied to study the strong decays of baryons and heavy-light mesons [24,25,[30][31][32][33][34][35][36][37][38][39][40][41][42]. In the chiral quark model, the effective low energy quark-pseudoscalar-meson coupling in the SU(3) flavor basis at tree level is described by [43]…”

Interpretation of the observed Λb(6146)0 and ΛbChen1, Luo2, Liu3 et al. 2019Phys. Rev. D366322View full textAdd to dashboardCite

“…Then, the possible interference effects, which were ignored in the LHCb analysis [12], might be important to pin down the decay behaviors of Λ b ð6146Þ 0 and Λ b ð6152Þ 0 . Another possible explanation is that the mass inversion may occur for the 1D Λ 0 b states [32,33]. That is to say, the Λ b ð6146Þ 0 with smaller mass should be the J P ¼ 5=2 þ state, while the Λ b ð6152Þ 0 should be a J P ¼ 3=2 þ state.…”