(2030) production in K−p reactions at 4.2 GeV/c

The Ξ 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 Ξ'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 Ξ(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 Ξ'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 Ξ(1690) can be naturally explained in terms of coupled channel meson-baryon dynamics. We find another narrow resonance which can be related to Ξ(2120). We also look for exotic states Ξ + and Ξ −− but find none. In addition we provide the cross sections forKΛ,KΣ → πΞ which can be useful for understanding the enhanced yield of Ξ reported in recent studies of heavy ion collisions.

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“…This state was, however, not found in Ref. [23]. All these experimental data suffer from poor statistics.…”

Section: B ξ(2120)mentioning

confidence: 75%

Why Ξ(1690) and Ξ(2120) are so narrow

et al. 2018

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“…The quantum numbers are quite important as they directly determine the partial waves of the interaction, and high partial wave interactions should be suppressed in the near-threshold region. For the Ξ(2030) state, its spin is equal to or greater than 5/2 [75]. It leads to high partial-wave (l ≥ 2) interaction at the Ξ(2030)KΛ vertex, and will not be considered further.…”

Section: Theoretical Framework and Analysis Results Of All Possible Triangle Singularitiesmentioning

confidence: 99%

Exploring Possible Triangle Singularities in the Ξ b − → K − J / ψ Λ Decay

et al. 2020

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We analyze possible singularities in the J/ψΛ invariant mass distribution of the Ξb−→K−J/ψΛ process via triangle loop diagrams. Triangle singularities in the physical region are found in 18 different triangle loop diagrams. Among those with Ξ*-charmonium-Λ intermediate states, the one from the χc1Ξ(2120)Λ loop, which is located around 4628 MeV, is found the most likely to cause observable effects. One needs S- and P-waves in χc1Λ and J/ψΛ systems, respectively, when the quantum numbers of these systems are 1/2+ or 3/2+. When the quantum numbers of the Ξ(2120) are JP=1/2+, 1/2− or 3/2+, the peak structure should be sharper than the other JP choices. This suggests that although the whole strength is unknown, we should pay attention to the contributions from the Ξ*-charmonium-Λ triangle diagram if structures are observed in the J/ψΛ invariant mass spectrum experimentally. In addition, a few triangle diagrams with the Ds1*(2700) as one of the intermediate particles can also produce singularities in the J/ψΛ distribution, but at higher energies above 4.9 GeV.

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“…Since K * and Σ carries spin parities 1 − and 1/2 + , respectively, an S -wave bound state should have spin parity 1/2 − or 3/2 − . An early experimental analysis [35] suggested that the Ξ(2030) should carry a spin J ≥ 5/2. It requires that the Ξ(2030) is at least a P-wave state if it is a K * Σ molecular state.…”

Section: Resultsmentioning

confidence: 99%

“…It seems to favor the J P = 3/2 + assignment. However, this conflicts with the analysis of the data [35]. Generally speaking, the Ξ(2030) can not easily be understood as a conventional qqq state.…”

Section: Introductionmentioning

confidence: 99%

“…The Ξ(2030) is a three-star state and has a mass of 2025 ± 5 MeV and a width of 20 +15 −5 MeV [16]. An early experimental analysis [35] suggested that the spin of the Ξ(2030) should be J ≥ 5/2. Before the experimental observation of the Ξ(2030), Samios et al predicted that according to the SU(3) flavor symmetry the Ξ(2030) is most likely the partner of the N(1680), Λ(1820) and Σ(1915) with J P = 5/2 + [36].…”

Section: Introductionmentioning

confidence: 99%

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$Ξ$(2030) and $Ξ$(2120) as $\bar{K}^*Σ$ molecular states

Huang,

Wang,

et al. 2018

Preprint

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In this work, the molecular states from the K * Σ interaction are studied in a quasipotential Bethe-Salpeter equation approach with the one-boson-exchange potentials. We consider the exchanges of vector (ρ, ω and φ) mesons and pseudoscalar (π and η) mesons to describe the K * Σ interaction with the coupling constants determined by the SU(3) symmetry, The poles of the scattering amplitude are searched for to find the molecular states dynamically generated from the K * Σ interaction. A bound state with quantum number I(J p ) = 1/2(5/2 + ) is produced, which can be associated to the Ξ(2030) baryon. Other bound states with J ≤ 5/2 are also searched for and it is found that there exist bound states with quantum numbers I(J P ) = 1/2(1/2 − ), 1/2(3/2 − ), and 1/2(3/2 + ). The Ξ(2120) may be a candidate for one of these three bound states. In addition, we also find two bound states with isospin 3/2 and spin parities 1/2 − and 1/2 + .

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(2030) production in K−p reactions at 4.2 GeV/c

Cited by 19 publications

References 9 publications

Why Ξ(1690) and Ξ(2120) are so narrow

Why Ξ(1690) and Ξ(2120) are so narrow

Exploring Possible Triangle Singularities in the Ξ b − → K − J / ψ Λ Decay

$Ξ$(2030) and $Ξ$(2120) as $\bar{K}^*Σ$ molecular states

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