Theoretical study of the Ξ(1620) and Ξ(1690) resonances in

Abstract

Nonleptonic weak decays of Ξc into π + and a meson (M )-baryon (B) final state, M B, are analyzed from the viewpoint of probing S = −2 baryon resonances, i.e., Ξ(1620) and Ξ(1690), of which spinparity and other properties are not well known. We argue that the weak decay of Ξc is dominated by a single quark-line diagram, preferred by the Cabibbo-Kobayashi-Maskawa coefficient, color recombination factor, the diquark correlation, and the kinematical condition. The decay process has an advantage of being free from meson resonances in the π + M invariant mass distribution. The invariant mass distribution of the meson-baryon final state is calculated with three different chiral unitary approaches, assuming that the Ξ(1620) and Ξ(1690) resonances have J P = 1/2 − . It is found that a clear peak for the Ξ(1690) is seen in the πΞ andKΛ spectra. We also suggest that the ratios of the πΞ,KΛ andKΣ final states are useful to distinguish whether the peak is originated from the Ξ(1690) resonance or it is aKΣ threshold effect.

Anomalous enhancement of the isospin-violating Λ(1405) production by a triangle singularity in Λc→

“…[55] (see Table III of that work), we see that, in terms of three quarks, the mixed antisymmetric representation of…”

$$\Lambda _b \rightarrow \pi ^- (D_s^-) \Lambda _c(2595),~\pi ^- (D_s^-) \Lambda _c(2625)$$ Λ b → π - ( D s - ) Λ c ( 2595 ) , π - ( D s - ) Λ c ( 2625 ) decays and $$DN,~D^*N$$ D N , D ∗ N molecular components

“…[13] the b → J/ψ K reaction was studied, which sheds light on the pseudoscalar-baryon interaction at energies above the (1405) region. More recently the c → π + M B reaction has also been shown to be a good tool to investigate the (1620) and (1690) resonances [14]. Related reactions aimed at the production of pentaquark states have been reviewed in Refs.…”

Ξ(1690)− Resonance Production via K−p → K+K−Λ

“…S = −2 three-star baryon states include Ξ(1690) − , Ξ(1820)(J p = 3/2 − ), Ξ(1950), and Ξ(2030). The third state of Ξ has not yet been confirmed between Ξ(1620) and Ξ(1690) − [2][3][4][5][6][7][8]. Ξ(1690) − is near the ΣK threshold, and its existence has been firmly established by several experiments [9][10][11][12].…”