Editorial

Lopes, Marcela Coronel; Carriconde, Raquel; Menezes, Márcia Mendes

doi:10.12957/intratextos.2013.8906

Cited by 3 publications

(12 citation statements)

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“…The following values are commonly assumed: tan θ = 1/ √ 2, corresponding to ideal ω-φ-mixing, α = 1, and z = 1/ √ 6. The latter value reflects an underlying SU (6)symmetry, and only recent studies in view of the observation of high mass neutron stars have relaxed this assumption, for example [18,22,61,84], or even varied freely the hyperonic isoscalar vector couplings, see e.g. [26].…”

Section: Relativistic Mean Field Models For the Eosmentioning

confidence: 99%

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Hyperons in neutron stars and supernova cores

et al. 2016

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The properties of compact stars and their formation processes depend on many physical ingredients. The composition and the thermodynamics of the involved matter is one of them. We will investigate here uniform strongly interacting matter at densities and temperatures, where potentially other components than free nucleons appear such as hyperons, mesons or even quarks. In this paper we will put the emphasis on two aspects of stellar matter with non-nucleonic degrees of freedom. First, we will study the phase diagram of baryonic matter with strangeness, showing that the onset of hyperons, as that of quark matter, could be related to a very rich phase structure with a large density domain covered by phase coexistence. Second, we will investigate thermal effects on the equation of state (EoS), showing that they favor the appearance of non-nucleonic particles. We will finish by reviewing some recent results on the impact of non-nucleonic degrees freedom in compact star mergers and core-collapse events, where thermal effects cannot be neglected.PACS. PACS-key discribing text of that key -PACS-key discribing text of that key 1 An order parameter is defined here as the direction in the observable space corresponding to phase separation, see e.g. Ref.[35] for details

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Section: Relativistic Mean Field Models For the Eosmentioning

confidence: 99%

“…This observation, however, does not exclude them, but only puts stringent constraints on the respective interaction (e.g. [14,15,16,17,18,19,20,21,22,23,24,25,26]). Different solutions with hyperonic and/or quark matter have been proposed without any definite conclusion.…”

Section: Introductionmentioning

confidence: 99%

Hyperons in neutron stars and supernova cores

et al. 2016

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“…In the case of the inclusion of the strange mesons, σ * and φ , the same degree of arbitrariness is found, i.e., their couplings with the hyperons have generally obeyed SU(6) symmetry based on quark counting [29,30]. A choice of couplings based on a mixture of arguments [49] and on SU(3) symmetry [19,20,24] has also been done. If massive stars are to be obtained, the SU( 6) symmetry has to be partially broken and, in this case, strange mesons can couple with the nucleons, influencing nuclear bulk properties and forcing a reparameterisation [24].…”

Section: Formalismmentioning

confidence: 93%

“…A choice of couplings based on a mixture of arguments [49] and on SU(3) symmetry [19,20,24] has also been done. If massive stars are to be obtained, the SU( 6) symmetry has to be partially broken and, in this case, strange mesons can couple with the nucleons, influencing nuclear bulk properties and forcing a reparameterisation [24]. In the present work we avoid the discussion based on group theory and focus our choice on the phenomenological information that can be extracted on the U Λ Λ potential for the meson-Λ couplings.…”

Section: Formalismmentioning

confidence: 99%

“…Meanwhile, many hypernuclei have been synthesised and recent analyses of double-Λ hypernuclei suggests an attraction, though small, in the in the Λ − Λ channel [16]. To fulfill these different requirements, it has become evident that one has to go beyond simple SU (6) symmetry arguments to fix hyperon couplings, and more elaborate models have to be considered [17][18][19][20][21][22][23][24][25][26][27][28]. In the framework of relativistic mean field models (RMF), this is achieved by the inclusion of strange scalar and vector mesons [29,30] mediating the nuclear force alongside the usual scalar-isoscalar σ or f 0 (550), vector-isoscalar ω(782) and vector-isovector ρ(770) mesons.…”

Section: Introductionmentioning

confidence: 99%

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Examination of strangeness instabilities and effects of strange meson couplings in dense strange hadronic matter and compact stars

2017

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International audienceBackground : The emergence of hyperon degrees of freedom in neutron star matter has been associated to first order phase transitions in some phenomenological models, but conclusions on the possible physical existence of an instability in the strangeness sector are strongly model dependent. Purpose : The purpose of the present study is to assess whether strangeness instabilities are related to specific values of the largely unconstrained hyperon interactions, and to study the effect of the strange meson couplings on phenomenological properties of neutron stars and supernova matter, once these latter are fixed to fulfill the constraints imposed by hypernuclear data. Method : We consider a phenomenological RMF model sufficiently simple to allow a complete exploration of the parameter space. Results : We show that no instability at supersaturation density exists for the RMF model, as long as the parameter space is constrained by basic physical requirements. This is at variance with a non-relativistic functional, with a functional behavior fitted through ab-initio calculations. Once the study is extended to include the full octet, we show that the parameter space allows reasonable radii for canonical neutron stars as well as massive stars above two-solar mass, together with an important strangeness content of the order of 30\%, slightly decreasing with increasing entropy, even in the absence of a strangeness driven phase transition. Conclusions : We conclude that the hyperon content of neutron stars and supernova matter cannot be established with present constraints, and is essentially governed by the unconstrained coupling to the strange isoscalar meson

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Many-Body Forces in the Equation of State of Hyperonic Matter

Gomes

Dexheimer

Schramm

et al. 2015

ApJ

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In this work we introduce an extended version of the formalism proposed originally by Taurines et al. that considers the effects of many-body forces simulated by non-linear self-couplings and mesonmeson interaction contributions. In this extended version of the model, we assume that matter is at zero temperature, charge neutral and in beta-equilibrium, considering that the baryon octet interacts by the exchange of scalar-isoscalar (σ, σ * ), vector-isoscalar (ω, φ), vector-isovector ( ) and scalar-isovector (δ) meson fields. Using nuclear matter properties, we constrain the parameters of the model that describe the intensity of the indirectly density dependent baryon-meson couplings to a small range of possible values. We then investigate asymmetric hyperonic matter properties. We report that the formalism developed in this work is in agreement with experimental data and also allows for the existence of massive hyperon stars (with more than 2M ) with small radii, compatible with astrophysical observations.

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Editorial

Cited by 3 publications

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Hyperons in neutron stars and supernova cores

Hyperons in neutron stars and supernova cores

Examination of strangeness instabilities and effects of strange meson couplings in dense strange hadronic matter and compact stars

Many-Body Forces in the Equation of State of Hyperonic Matter

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