On the hidden charm pentaquarks in $$\Lambda _b \rightarrow J/\psi K^- p$$ Λ b → J / ψ K - p decay

Abstract

In a previous work we presented a theoretical analysis of the b → J/ψ K − p reaction based on which a recent experiment by the LHCb collaboration at CERN claimed the existence of two hidden charm pentaquarks, P c (4380) + and P c (4450) + . In that work we focused only on the (1405) and P c (4450) + signals and discussed the possible explanation of this pentaquark state within the picture of a dynamical meson-baryon molecule made up mostly fromD * c andD * * c components. In the present work we improve upon the previous one by considering the total K − p and J/ψ p data including all the relevant resonances contributing to the spectra, and discuss the possible nature of both P c (4380) + and P c (4450) + . We also discuss several important topics, like the effect of the contact term in the reaction, the viability of reproducing the data without the P c (4380) + and the possible quantum number assignment to these pentaquarks.

Hidden charm pentaquarks in $\Lambda_b \to J/\psi K^- p$ decay

“…In the present section, which is a summary of the work in ref. [6], we aim at reproducing the total K − p and J/ψ p invariant mass and thus we must add the relevant Λ contributions to the process. In our analysis it is enough to consider only those Λ resonances which gave a sizable contribution to the final cross section in [1] which, in addition to the Λ(1405) discussed above, turn out to be Λ(1520) (3/2 − ), Λ(1600) (1/2 + ), Λ(1690) (3/2 − ), Λ(1800) (1/2 − ) and Λ(1810) (1/2 + ).…”

“…The Λ resonances (except the Λ(1405) which, as explained above, is dynamically generated) are parametrized by a Breit-Wigner shape with Flatté parametrization of the width, considering also spin and momentum structure of the resonance (see the Appendix of ref. [6]). Furthermore, contact terms with the different spin and angular momentum of the J/ψ and kaon are also considered as explained in the Appendix of ref.…”

“…Furthermore, contact terms with the different spin and angular momentum of the J/ψ and kaon are also considered as explained in the Appendix of ref. [6]). These contact terms were found to be negligible in the experimental fit [1] but we will explain in the results section that some of them could indeed play an important role.…”

“…Furthermore, in ref [6] we provide a wide discussion of the important role played by the tree level contact elementary Λ b → J/ψK − p production and the K − p rescattering. The interference of these two terms gives rise to the Λ(1405) resonance in our case, and we showed that this procedure, implementing unitarity in coupled channels, produced results in remarkable agreement with those of the analysis of [1], where a Λ(1405) resonance Breit-Wigner term (accounting for Flatté effect) was introduced.…”

Synthesis, crystal structure and magnetic properties of a new tri‐nuclear iron (II, III) complex, a precursor for the preparation of superparamagnetic Fe3O4 nanoparticles applicable in the removal of Cd2+

“…[12] The thermal degradation of iron complexes is a well-established method for the preparation of pure Fe 3 O 4 nanoparticles, which has been reported by a number of researchers. [13][14][15][16][17] Nanoparticles are known as efficient adsorbents. Among them, nano-magnets are widely used adsorbents with an evident advantage that they can be easily removed from water under magnetic field, and they have a small diffusion resistance.…”