Strangeness in nuclei and neutron stars

Tolós, Laura; Fabbietti, L.

doi:10.1016/j.ppnp.2020.103770

“…Additionally, a precise knowledge of the Y – N and Y – Y interactions has important consequences for the physics of neutron stars. Indeed, the structure of the innermost core of neutron stars is still completely unknown and hyperons could appear in such environments depending on the Y – N and Y – Y interactions 36 . Real progress in this area calls for new experimental methods.…”

mentioning

confidence: 99%

Unveiling the strong interaction among hadrons at the LHC

2020

Nature

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One of the key challenges for nuclear physics today is to understand from first principles the effective interaction between hadrons with different quark content. First successes have been achieved using techniques that solve the dynamics of quarks and gluons on discrete space-time lattices1,2. Experimentally, the dynamics of the strong interaction have been studied by scattering hadrons off each other. Such scattering experiments are difficult or impossible for unstable hadrons3–6 and so high-quality measurements exist only for hadrons containing up and down quarks7. Here we demonstrate that measuring correlations in the momentum space between hadron pairs8–12 produced in ultrarelativistic proton–proton collisions at the CERN Large Hadron Collider (LHC) provides a precise method with which to obtain the missing information on the interaction dynamics between any pair of unstable hadrons. Specifically, we discuss the case of the interaction of baryons containing strange quarks (hyperons). We demonstrate how, using precision measurements of proton–omega baryon correlations, the effect of the strong interaction for this hadron–hadron pair can be studied with precision similar to, and compared with, predictions from lattice calculations13,14. The large number of hyperons identified in proton–proton collisions at the LHC, together with accurate modelling15 of the small (approximately one femtometre) inter-particle distance and exact predictions for the correlation functions, enables a detailed determination of the short-range part of the nucleon-hyperon interaction.

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“…(11) in [38], one notices that the directions of the relative momenta are the same, however, the ordering of the coupling of the angular momenta and isospins in α * (1) * (Y ) and |α (13)2 are different. The recoupling from (T A−2 t N )T * (1) A−1 to (t NTA−2 )T * (1) A−1 requires a simple phase factor,…”

Section: Discussionmentioning

confidence: 99%

“…After more than 65 years of research on hypernuclei, our knowledge of the interaction of hyperons with nucleons or with other hyperons still remains on a modest level. This situation is rather unsatisfactory given the important role hyperons play for various aspects of nuclear physics as well as for astrophysics [1][2][3][4][5]. For example, as extensively discussed in recent years, the hyperon interaction could have a significant impact on the properties of neutron stars [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Jacobi no-core shell model for p-shell hypernuclei

Le

¹

,

Haidenbauer

²

,

Meißner

³

et al. 2020

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We extend the recently developed Jacobi no-core shell model to hypernuclei. Based on the coefficients of fractional parentage for ordinary nuclei, we define a basis where the hyperon is the spectator particle. We then formulate transition coefficients to states that single out a hyperon–nucleon pair which allow us to implement a hypernuclear many-baryon Hamiltonian for p-shell hypernuclei. As a first application, we use the basis states and the transition coefficients to calculate the ground states of $$^{4}_{\varLambda }\hbox {He}$$ Λ 4 He , $$^{4}_{\varLambda }\hbox {H}$$ Λ 4 H , $$^{5}_{\varLambda }\hbox {He}$$ Λ 5 He , $$^{6}_{\varLambda }\hbox {He}$$ Λ 6 He , $$^{6}_{\varLambda }\hbox {Li}$$ Λ 6 Li , and $$^{7}_{\varLambda }\hbox {Li}$$ Λ 7 Li and, additionally, the first excited states of $$^{4}_{\varLambda }\hbox {He}$$ Λ 4 He , $$^{4}_{\varLambda }\hbox {H}$$ Λ 4 H , and $$^{7}_{\varLambda }\hbox {Li}$$ Λ 7 Li . In order to obtain converged results, we employ the similarity renormalization group (SRG) to soften the nucleon–nucleon and hyperon-nucleon interactions. Although the dependence on this evolution of the Hamiltonian is significant, we show that a strong correlation of the results can be used to identify preferred SRG parameters. This allows for meaningful predictions of hypernuclear binding and excitation energies. The transition coefficients will be made publicly available as HDF5 data files.

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“…The EoS in neutron stars is needed so as to determine not only the speed of sound at T = 0, but also the phonon self-couplings. The theoretical description of matter in neutron stars is a complicated task given that the EoS spans over a wide range of densities, temperatures, and isospin asymmetries (see, for example, the recent review [15]). More precisely, inside the core of neutron stars, nuclear matter can be described using different theoretical many-body schemes.…”

Section: Equation Of State and The Gap Of Neutron Matter In Superfluimentioning

confidence: 99%

Transport Properties of Superfluid Phonons in Neutron Stars

Manuel

¹

,

Tolós

²

2021

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We review the effective field theory associated with the superfluid phonons that we use for the study of transport properties in the core of superfluid neutrons stars in their low temperature regime. We then discuss the shear and bulk viscosities together with the thermal conductivity coming from the collisions of superfluid phonons in neutron stars. With regard to shear, bulk, and thermal transport coefficients, the phonon collisional processes are obtained in terms of the equation of state and the superfluid gap. We compare the shear coefficient due to the interaction among superfluid phonons with other dominant processes in neutron stars, such as electron collisions. We also analyze the possible consequences for the r-mode instability in neutron stars. As for the bulk viscosities, we determine that phonon collisions contribute decisively to the bulk viscosities inside neutron stars. For the thermal conductivity resulting from phonon collisions, we find that it is temperature independent well below the transition temperature. We also obtain that the thermal conductivity due to superfluid phonons dominates over the one resulting from electron-muon interactions once phonons are in the hydrodynamic regime. As the phonons couple to the Z electroweak gauge boson, we estimate the associated neutrino emissivity. We also briefly comment on how the superfluid phonon interactions are modified in the presence of a gravitational field or in a moving background.

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Strangeness in nuclei and neutron stars

Cited by 189 publications

References 422 publications

Unveiling the strong interaction among hadrons at the LHC

Unveiling the strong interaction among hadrons at the LHC

Jacobi no-core shell model for p-shell hypernuclei

Transport Properties of Superfluid Phonons in Neutron Stars

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