Why Xi(1690) and Xi(2120) are so narrow
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Date
2018
Authors
Khemchandani, K. P. [UNIFESP]
Martinez Torres, A.
Hosaka, A.
Nagahiro, H.
Navarra, F. S.
Nielsen, M.
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Abstract
The Xi baryons are expected to be naturally narrower as compared to their nonstrange and strange counterparts since they have only one light quark and, thus, their decay involves producing either a light meson and doubly strange baryon or both meson and baryon with strangeness which involves, relatively, more energy. In fact, some Xi's have full widths of the order of even 10-20 MeV when, in principle, they have a large phase space to decay to some open channels. Such is the case of Xi(1690), for which the width has been found to be of the order of 10 MeV in the latest BABAR and BELLE data. In this manuscript we study why some Xi's are so narrow. Based on a coupled channel calculation of the pseudoscalar meson-baryon and vector meson-baryon systems with chiral and hidden local symmetry Lagrangians, we find that the answer lies in the intricate hadron dynamics. We find that the known mass, width, spin-parity, and branching ratios of Xi(1690) can be naturally explained in terms of coupled channel meson-baryon dynamics. We find another narrow resonance which can be related to Xi(2120). We also look for exotic states Xi(+) and Xi(--) but find none. In addition we provide the cross sections for (K) over bar Lambda (K) over bar Sigma -> pi Xi which can be useful for understanding the enhanced yield of Xi reported in recent studies of heavy ion collisions.
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Physical Review D. College Pk, v. 97, n. 3, p. -, 2018.