Role of nucleon strangeness in supernova explosions

Abstract

Recent hydrodynamical simulations of core-collapse supernova (CCSN) evolution have highlighted the importance of a thorough control over microscopic physics responsible for such internal processes as neutrino heating. In particular, it has been suggested that modifications to the neutrino-nucleon elastic cross section can potentially play a crucial role in producing successful CCSN explosions. One possible source of such corrections can be found in a nonzero value for the nucleon's strange helicity content ∆s. In the present analysis, however, we show that theoretical and experimental progress over the past decade has suggested a comparatively small magnitude for ∆s, such that its sole effect is not sufficient to provide the physics leading to CCSN explosions.

Gravitational wave emission from 3D explosion models of core-collapse supernovae with low and normal explosion energies

“…Different from previous 3D simulations with CoCoNuT-FMT, we simulate in 3D down to the innermost ∼ 10 km to include the PNS convection zone and impose spherical symmetry inside this radius. The neutrino transport is handled using the fast multigroup transport method of with updates to the neutrino rates to include nucleon potentials (Martínez-Pinedo et al 2012), nucleon correlations in the virial approximation , weak magnetism (Horowitz 2002), and a nucleon strangeness of g A = −0.05, which is roughly compatible with current experimental constraints and theoretical expectations (Hobbs et al 2016). To keep the computational costs manageable despite resolving the PNS convection zone in 3D, we adopt a coarser grid in energy space with only 9 energy groups (instead of the usual 21 energy groups in our recent models).…”

Impact of Neutrino Opacities on Core-collapse Supernova Simulations

“…In set6b, we employ the formulas suggested by Horowitz et al (2017) for the neutral-current axial response that accounts for virial effects at low density and many-body correlations at high densities ). Finally in set6c, a strangenessdependent contribution to the axial-vector coupling constant (Horowitz 2002) with g s A = −0.1 (Hobbs et al 2016) is considered for neutrino-nucleon scattering.…”

“…In the original IDSA scheme ), a base-line set of neutrino opacities (Bruenn 1985) (often referred to as the Bruenn rate) is used. Following the implementation schemes of microphysical update in the literature (e.g., Buras et al (2006b); Fischer et al (2009);Fischer (2016)), we 1 In order to clearly see the effect, Melson et al (2015a) chose a relatively high strangeness contribution (g s a = −0.2) to the axial vector coupling constant (ga ≈ 1.26) compared to the constraint (g s a −0.1) proposed by Hobbs et al (2016). study how individual update in the neutrino opacity leads to differences from the base-line run with the Bruenn rate.…”

Bayesian analysis of light-front models and the nucleon’s charmed sigma term

“…1(a) and 1(b). This physical picture has antecedents in treatments of the nucleon's strange [31,32] and bare valence quark content [33], and in both cases LFWFs were an advantageous means of computing the quark-level PDFs. We extend this framework to model IC in DIS in Sect.…”

“…DIS sector a. Collinear PDF. LFWFs provide a systematic, covariant description of the nucleon's partonic substructure as imaged in external electromagnetic interactions and have recently been used to analyze the strange component of the proton's form factors [31,32]. Following this earlier work, the leading contribution to the proton's charm content in DIS can be obtained in analogous fashion by expanding its wave function in terms of a 5-quark state, for which the leading component is taken to consist of a struck charm quark/antiquark accompanied by a recoiling 4-quark scalar spectator as shown in Fig.…”