Critical density and impact of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="normal">Δ</mml:mi><mml:mo>(</mml:mo><mml:mn>1232</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:math>resonance formation in neutron stars

Cai, Bao-Jun; Fattoyev, F. J.; Li, Bao-An; Newton, William

doi:10.1103/physrevc.92.015802

Cited by 106 publications

(131 citation statements)

References 121 publications

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“…As to the mean-field potential of ∆ resonances in nuclear medium [14,19], it is commonly assumed in transport models that its isoscalar part is the same as that for nucleon, but its isovector part is taken to be the weighted average of those for neutron and proton according to the squared Clebsch-Gordan coefficients from * zhenzhang@comp.tamu.edu † ko@comp.tamu.edu its isospin structure [1,20]. This assumption leads to a change between the initial and final potentials in some of the processes N + N ↔ N + ∆ and ∆ ↔ N + π.…”

Section: Introductionmentioning

confidence: 99%

Effects of energy conservation on equilibrium properties of hot asymmetric nuclear matter

Zhang

2018

Phys. Rev. C

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Based on the relativistic Vlasov-Uehling-Uhlenbeck transport model, which includes relativistic scalar and vector potentials on baryons, we consider a N − ∆ − π system in a box with periodic boundary conditions to study the effects of energy conservation in particle production and absorption processes on the equilibrium properties of the system. The density and temperature of the matter in the box are taken to be similar to the hot dense matter formed in heavy ion collisions at intermediate energies. We find that to maintain the equilibrium numbers of N , ∆ and π, which depend on the mean-field potentials of N and ∆, requires the inclusion of these potentials in the energy conservation condition that determines the momenta of outgoing particles after a scattering or decay process. We further find that the baryon scalar potentials mainly affect the ∆ and pion equilibrium numbers, while the baryon vector potentials have considerable effects on the effective charged pion ratio at equilibrium. Our results thus indicate that it is essential to include in the transport model the effect of potentials in the energy conservation of a scattering or decay process, which is ignored in most transport models, for studying pion production in heavy ion collisions.

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Section: Introductionmentioning

confidence: 99%

Effects of energy conservation on equilibrium properties of hot asymmetric nuclear matter

Zhang

2018

Phys. Rev. C

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“…In particular, it has been extensively discussed in the literature whether exotic degrees of freedom might populate the core of neutron stars. On the one hand, it is more energetically favorable for the system to populate new degrees of freedom, such as hyperons (Dexheimer & Schramm 2008;Ishizuka et al 2008;Bednarek et al 2012;Fukukawa et al 2015;Gomes et al 2015;Maslov et al 2015;Oertel et al 2015;Lonardoni et al 2015Lonardoni et al , 2016; Biswal et al 2016;Burgio & Zappalà 2016;Chatterjee & Vidana 2016;Mishra et al 2016;Vidaña 2016;Yamamoto et al 2016;Tolos et al 2017); Torres et al 2017), delta isobars (Fong et al 2010;Schurhoff et al 2010;Drago et al 2014;Cai et al 2015;Zhu et al 2016), and meson condensates (Ellis et al 1995;Menezes et al 2005;Takahashi 2007;Ohnishi et al 2009;Alford et al 2010;Fernandez et al 2010;Mesquita et al 2010;Mishra et al 2010;Lim et al 2014;Muto et al 2015), in order to lower its Fermi energy (starting at about two times the saturation density). On the other hand, the EoS softening due to the appearance of exotica might turn some nuclear models incompatible with observational data, in particular with the recently measured massive neutron stars.…”

Section: Introductionmentioning

confidence: 99%

Many-body Forces in Magnetic Neutron Stars

Gomes

Franzon

Dexheimer

et al. 2017

ApJ

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In this work, we study in detail the effects of many-body forces on the equation of state and the structure of magnetic neutron stars. The stellar matter is described within a relativistic mean field formalism that takes into account many-body forces by means of a nonlinear meson field dependence on the nuclear interaction coupling constants. We assume that matter is at zero temperature, charge neutral, in beta equilibrium, and populated by the baryon octet, electrons, and muons. In order to study the effects of different degrees of stiffness in the equation of state, we explore the parameter space of the model, which reproduces nuclear matter properties at saturation, as well as massive neutron stars. Magnetic field effects are introduced both in the equation of state and in the macroscopic structure of stars by the self-consistent solution of the Einstein-Maxwell equations. In addition, the effects of poloidal magnetic fields on the global properties of stars, as well as density and magnetic field profiles, are investigated. We find that not only different macroscopic magnetic field distributions but also different parameterizations of the model for a fixed magnetic field distribution impact the gravitational mass, deformation, and internal density profiles of stars. Finally, we show that strong magnetic fields significantly affect the particle populations of stars.

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“…However, the relationship between the isovector potentials of nucleons and baryon resonances in isospin-asymmetric matter is completely unknown. In fact, the critical density for ∆(1232) resonance formation in neutron stars has been found to depend almost linearly on the unknown ratio x ρ ≡ g ρ∆ /g ρN [45,46]. Depending on the assumed value of x ρ , the formation of ∆(1232) resonance can even happen at ρ 0 and affect significantly properties of neutron stars [46].…”

Section: Modeling the Symmetry Potentials Of Nucleons And ∆(1232)mentioning

confidence: 99%

“…In fact, the critical density for ∆(1232) resonance formation in neutron stars has been found to depend almost linearly on the unknown ratio x ρ ≡ g ρ∆ /g ρN [45,46]. Depending on the assumed value of x ρ , the formation of ∆(1232) resonance can even happen at ρ 0 and affect significantly properties of neutron stars [46]. In addition, the isovecor Lorentz-scalar δ-meson may also play some roles in determining the baryon isovector potentials.…”

Section: Modeling the Symmetry Potentials Of Nucleons And ∆(1232)mentioning

confidence: 99%

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Symmetry potential of theΔ(1232)resonance and its effects on theπ−/π+ratio in heavy-ion collisions near the pion-prod

2015

Phys. Rev. C

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Effects of the completely unknown symmetry (isovector) potential of the ∆(1232) resonance on the total and differential π − /π + ratio in heavy-ion collisions at beam energies from 100 to 1000 MeV/A are explored within an isospin-dependent transport model IBUU. The effects are found to be negligible at beam energies above the pion production threshold due to the very short lifetimes of less than 2 fm/c for ∆ resonances with masses around m∆ = 1232 MeV, leaving the π − /π + ratios of especially the energetic pions still a reliable probe of the high-density behavior of nuclear symmetry energy Esym(ρ). However, as the beam energy becomes deeply sub-threshold for pion production, effects of the ∆ symmetry potential becomes appreciable especially on the π − /π + ratio of low-energy pions from the decays of low-mass ∆ resonances which have lived long enough to be affected by their mean-field potentials, providing a useful tool to study the symmetry potential and spectroscopy of ∆ resonances in neutron-rich nuclear matter. Interestingly though, even at the deeply sub-threshold beam energies, the differential π − /π + ratio of energetic pions remains sensitive to the Esym(ρ) at supra saturation densities with little influence from the uncertain symmetry potential of the ∆ resonance.

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Critical density and impact ofΔ(1232)resonance formation in neutron stars

Cited by 106 publications

References 121 publications

Effects of energy conservation on equilibrium properties of hot asymmetric nuclear matter

Effects of energy conservation on equilibrium properties of hot asymmetric nuclear matter

Many-body Forces in Magnetic Neutron Stars

Symmetry potential of theΔ(1232)resonance and its effects on theπ−/π+ratio in heavy-ion collisions near the pion-prod

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