346 research outputs found

    Resonances and the Weinberg--Tomozawa 56-baryon --35-meson interaction

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    Vector meson degrees of freedom are incorporated into the Weinberg-Tomozawa (WT) meson-baryon chiral Lagrangian by using a scheme which relies on spin--flavor SU(6) symmetry. The corresponding Bethe-Salpeter approximation successfully reproduces previous SU(3)--flavor WT results for the lowest-lying s--wave negative parity baryon resonances, and it also provides some information on the dynamics of the heavier ones. Moreover, it also predicts the existence of an isoscalar spin-parity 32\frac32^- KNK^*N bound state (strangeness +1) with a mass around 1.7--1.8 GeV, unstable through KK^* decay. Neglecting d-wave KN decays, this state turns out to be quite narrow (Γ15\Gamma \le 15 MeV) and it might provide clear signals in reactions like γpKˉ0pK+π\gamma p \to \bar K^0 p K^+\pi^- by looking at the three body pK+πp K^+\pi^- invariant mass.Comment: Talk given at the IVth International Conference on Quarks an Nuclear Physics, Madrid, June 5th-10th 2006. Minor correction

    Quark-mass dependence of baryon resonances

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    We study the quark-mass dependence of J^P = \frac12^- s-wave and J^P = \frac32^- d-wave baryon resonances. Parameter-free results are obtained in terms of the leading order chiral Lagrangian. In the 'heavy' SU(3) limit with m_\pi =m_K \simeq 500 MeV the s-wave resonances turn into bound states forming two octets plus a singlet representations of the SU(3) group. Similarly the d-wave resonances turn into bound states forming an octet and a decuplet in this limit. A contrasted result is obtained in the 'light' SU(3) limit with m_\pi =m_K \simeq 140 MeV for which no resonances exist.Comment: 8 pages, three figures, talk presented at HYP200

    Odd Parity Light Baryon Resonances

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    We use a consistent SU(6) extension of the meson-baryon chiral Lagrangian within a coupled channel unitary approach in order to calculate the T-matrix for meson-baryon scattering in s-wave. The building blocks of the scheme are the pion and nucleon octets, the rho nonet and the Delta decuplet. We identify poles in this unitary T-matrix and interpret them as resonances. We study here the non exotic sectors with strangeness S=0,-1,-2,-3 and spin J=1/2, 3/2 and 5/2. Many of the poles generated can be associated with known N, Delta, Sigma, Lambda and Xi resonances with negative parity. We show that most of the low-lying three and four star odd parity baryon resonances with spin 1/2 and 3/2 can be related to multiplets of the spin-flavor symmetry group SU(6). This study allows us to predict the spin-parity of the Xi(1620), Xi(1690), Xi(1950), Xi(2250), Omega(2250) and Omega(2380) resonances, which have not been determined experimentally yet.Comment: New appendix and references adde

    Influence of gender determinants on informal care and health service utilization in Spain: Ten years after the approval of the equality law

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    The existence of gender inequalities in health, in the use of health services, and in the development of informal care has been demonstrated throughout scientific literature. In Spain, a law was passed in 2007 to promote effective equality between men and women. Despite this, different studies have shown that the previous gender inequalities are still present in Spanish society. For all these reasons, the objective of this paper is to study the differences by sex in informal care and in the use of emergency care, and to identify the existence of gender inequalities in Spain 10 years after the adoption of the aforementioned equality law. In this case, we development a cross-sectional study based on the 2017 Spanish National Health Survey of the Spanish population aged 16 and over. To analyze the influence of gender determinants on informal care and emergency care utilization, logistic regressions were performed, model 1 was adjusted for age, and model 2 was further adjusted too by the variables of the Andersen care demand model. The results showed that informal care and the use of the emergency care continues to be higher in women than in men. Informal care in women was related to a higher level of education. In emergency care, the older the age, the lower the probability of utilization, and living in a rural municipality was related to a higher probability of utilization for both sexes. Finally, we concluded that there is still a need for studies that analyze gender inequalities in different contexts, such as the informal care and the use of health services. This is especially relevant in Spain, where economic changes have led to a change in roles, mainly for women, and new management strategies are needed to achieve equity in care and effective equality between men and women

    Clood CBR: towards microservices oriented case-based reasoning.

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    CBR applications have been deployed in a wide range of sectors, from pharmaceuticals; to defence and aerospace to IoT and transportation, to poetry and music generation; for example. However, a majority of these have been built using monolithic architectures which impose size and complexity constraints. As such these applications have a barrier to adopting new technologies and remain prohibitively expensive in both time and cost because changes in frameworks or languages affect the application directly. To address this challenge, we introduce a distributed and highly scalable generic CBR system, Clood, which is based on a microservices architecture. This splits the application into a set of smaller, interconnected services that scale to meet varying demands. Experimental results show that our Clood implementation retrieves cases at a fairly consistent rate as the casebase grows by several orders of magnitude and was over 3,700 times faster than a comparable monolithic CBR system when retrieving from half a million cases. Microservices are cloud-native architectures and with the rapid increase in cloud-computing adoption, it is timely for the CBR community to have access to such a framework

    Double Λ\Lambda and the ΛΛ\Lambda-\Lambda Interaction

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    The Λ\Lambda-Λ\Lambda effective interaction, in the channel L=S=0L=S=0, in the nuclear medium is fitted to the available binding energies, BΛΛB_{\Lambda\Lambda}, of double Λ\Lambda hypernuclei: ΛΛ6^{6}_{\Lambda\Lambda}He, ΛΛ10^{10}_{\Lambda\Lambda}Be and ΛΛ13^{13}_{\Lambda\Lambda}B. The mesonic decay of these hypernuclei is also investigated. Finally, this effective interaction is used to predict the binding energies and mesonic decays widths of heavier double Λ\Lambda hypernuclei.Comment: 4 pages, (latex file, postscript-file and 3 Postscript-figures included

    Low-lying even parity meson resonances and spin-flavor symmetry

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    A study is presented of the ss-wave meson-meson interactions involving members of the ρ\rho-nonet and of the π\pi-octet. The starting point is an SU(6) spin-flavor extension of the SU(3) flavor Weinberg-Tomozawa Lagrangian. SU(6) symmetry breaking terms are then included to account for the physical meson masses and decay constants, while preserving partial conservation of the axial current in the light pseudoscalar sector. Next, the TT-matrix amplitudes are obtained by solving the Bethe Salpeter equation in coupled-channel with the kernel built from the above interactions. The poles found on the first and second Riemann sheets of the amplitudes are identified with their possible Particle Data Group (PDG) counterparts. It is shown that most of the low-lying even parity PDG meson resonances, specially in the JP=0+J^P=0^+ and 1+1^+ sectors, can be classified according to multiplets of the spin-flavor symmetry group SU(6). The f0(1500)f_0(1500), f1(1420)f_1(1420) and some 0+(2++)0^+(2^{++}) resonances cannot be accommodated within this SU(6) scheme and thus they would be clear candidates to be glueballs or hybrids. Finally, we predict the existence of five exotic resonances (I3/2I \ge 3/2 and/or Y=2|Y|=2) with masses in the range 1.4--1.6 GeV, which would complete the 27127_1, 10310_3, and 10310_3^* multiplets of SU(3)\otimesSU(2).Comment: 43 pages, 2 figures, 61 tables. Improved discussion of Section II. To appear in Physical Review
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