Abstract
We have studied the meson-baryon S−wave interaction in the isoscalar hidden-charm strange sector with the coupled-channels, ηcΛ, J/ψΛ, D¯Ξc, D¯sΛc, D¯Ξc′, D¯⁎Ξc, D¯s⁎Λc, D¯⁎Ξc′, D¯⁎Ξc⁎ in JP=1/2−, J/ψΛ, D¯⁎Ξc, D¯s⁎Λc, D¯⁎Ξc′, D¯Ξc⁎, D¯⁎Ξc⁎ in 3/2− and D¯⁎Ξc⁎ in 5/2−. We impose constraints of heavy quark spin symmetry in the interaction and obtain the non vanishing matrix elements from an extension of the local hidden gauge approach to the charm sector. The ultraviolet divergences are renormalized using the same meson-baryon-loops regulator previously employed in the non-strange hidden charm sector, where a good reproduction of the properties of the newly discovered pentaquark states is obtained. We obtain five states of 1/2−, four of 3/2− and one of 5/2−, which could be compared in the near future with forthcoming LHCb experiments. The 5/2−, three of the 3/2− and another three of the 1/2− resonances are originated from isoscalar D¯(⁎)Ξc′ and D¯(⁎)Ξc⁎ interactions. They should be located just few MeV below the corresponding thresholds (4446, 4513, 4588 and 4655 MeV), and would be SU(3)-siblings of the isospin 1/2 D¯(⁎)Σc(⁎) quasi-bound states previously found, and that provided a robust theoretical description of the Pc(4440), Pc(4457) and Pc(4312) LHCb exotic states. The another two 1/2− and 3/2− states obtained in this work are result of the D¯(⁎)Ξc−Ds(⁎)Λc coupled-channels isoscalar interaction, are significantly broader than the others, with widths of the order of 15 MeV, being D¯s(⁎)Λc the dominant decay channel.
Highlights
The discovery of two pentaquark states of hidden charm in Refs. [1, 2] by the LHCb collaboration gave a boost to hadron physics, providing one example of baryon states that challenge the standard wisdom of the three quark structure
We study states that can couple to J/ψΛ, the channel where, by analogy to the J/ψp of Ref. [3], the new states could be observed
We take into account the lowest order (LO) constraints of heavy quark spin symmetry (HQSS) [39,40,41], which states that interactions should be independent of the spin of the heavy quark (Q), up to corrections of the order of O(ΛQCD/mQ), with mQ the heavy quark mass
Summary
The discovery of two pentaquark states of hidden charm in Refs. [1, 2] by the LHCb collaboration gave a boost to hadron physics, providing one example of baryon states that challenge the standard wisdom of the three quark structure. The Run-2 experiment of the collaboration [3] has added more precise information where the old narrow state has split into two differentiated structures and a former small fluctuation has given rise to a new distinct peak Predictions for these hidden charm states in that energy region had been done before [4,5,6,7,8,9,10,11,12] and, after their discovery, a large number of works were devoted to explain their possible structure or new reactions where they could be alternatively obtained. The information provided by the new LHCb experiment [3] has been very useful to tune the theories for unknown information In this sense the masses of the three states reported in Ref. The work of Ref. [4] has been complemented recently to evaluate decay modes and rates of the states found in Refs. [4, 37], estimating the uncertainties [38]
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