Neutrino quantum kinetic equations

Volpe, Cristina

doi:10.1142/s0218301315410098

Cited by 93 publications

(77 citation statements)

References 93 publications

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“…A comprehensive study of the finite-temperature corrections to neutrino weak rates is thus still needed, and we only include QED corrections in the plasma thermodynamics. 2 The second effect that needs to be taken into account is neutrino flavor oscillations, and it requires trading distribution functions for a density matrix formalism [29][30][31][32][33][34]. The computation of collision integrals is considerably more demanding and has been performed over the last decade [21,35].…”

Section: A Neutrino Kinetic Equationsmentioning

confidence: 99%

Incomplete neutrino decoupling effect on big bang nucleosynthesis

Froustey

Pitrou

2020

Phys. Rev. D

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In the primordial Universe, neutrino decoupling occurs only slightly before electron-positron annihilations, leading to an increased neutrino energy density with order 10 −2 spectral distortions compared to the standard instantaneous decoupling approximation. However, there are discrepancies in the literature on the impact it has on the subsequent primordial nucleosynthesis, in terms of both the magnitude of the abundance modifications and their sign. We review how neutrino decoupling indirectly affects the various stages of nucleosynthesis, namely, the freezing out of neutron abundance, the duration of neutron beta decay, and nucleosynthesis itself. This allows to predict the sign of the abundance variations that are expected when the physics of neutrino decoupling is taken into account. For simplicity, we ignore neutrino oscillations, but we conjecture from the detailed interplay of neutrino temperature shifts and distortions that their effect on final light element abundances should be subdominant.

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Section: A Neutrino Kinetic Equationsmentioning

confidence: 99%

Incomplete neutrino decoupling effect on big bang nucleosynthesis

Froustey

Pitrou

2020

Phys. Rev. D

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“…The off-diagonal terms express correlations between the two flavors. The spacetime evolution equations of the density matrices are the quantum kinetic equations (QKEs) [42][43][44][45][46][47][48][49][50][51][52][53], which are given, in the limit that we neglect incoherent scattering, by:…”

Section: Model Setupmentioning

confidence: 99%

Effect of collisions on neutrino flavor inhomogeneity in a dense neutrino gas

2017

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We investigate the stability, with respect to spatial inhomogeneity, of a two-dimensional dense neutrino gas. The system exhibits growth of seed inhomogeneity due to nonlinear coherent neutrino self-interactions. In the absence of incoherent collisional effects, we observe a dependence of this instability growth rate on the neutrino mass spectrum: the normal neutrino mass hierarchy exhibits spatial instability over a larger range of neutrino number density compared to that of the inverted case. We further consider the effect of elastic incoherent collisions of the neutrinos with a static background of heavy, nucleon-like scatterers. At small scales, the growth of flavor instability can be suppressed by collisions. At large length scales we find, perhaps surprisingly, that for inverted neutrino mass hierarchy incoherent collisions fail to suppress flavor instabilities, independent of the coupling strength.

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“…We have departed from our convention of using a as the independent variable in order to be consistent with QKE literature (see Refs. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] for a discussion on QKEs).F is a 6 × 6 generalized density matrix where the occupation numbers of the 3 neutrinos and 3 antineutrinos fall along the diagonal of the matrix. The coherent evolution ofF is given by the commutator of a Hamiltonian-like potential withF .…”

Section: Full Neutrino Transport and Nonequilibrium Energy Distributionsmentioning

confidence: 99%

Insights into neutrino decoupling gleaned from considerations of the role of electron mass

Grohs

Fuller

2017

Nuclear Physics B

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We present calculations showing how electron rest mass influences entropy flow, neutrino decoupling, and Big Bang Nucleosynthesis (BBN) in the early universe. To elucidate this physics and especially the sensitivity of BBN and related epochs to electron mass, we consider a parameter space of rest mass values larger and smaller than the accepted vacuum value. Electromagnetic equilibrium, coupled with the high entropy of the early universe, guarantees that significant numbers of electron-positron pairs are present, and dominate over the number of ionization electrons to temperatures much lower than the vacuum electron rest mass. Scattering between the electrons-positrons and the neutrinos largely controls the flow of entropy from the plasma into the neutrino seas. Moreover, the number density of electron-positron-pair targets can be exponentially sensitive to the effective in-medium electron mass. This entropy flow influences the phasing of scale factor and temperature, the charged current weak-interaction-determined neutron-to-proton ratio, and the spectral distortions in the relic neutrino energy spectra. Our calculations show the sensitivity of the physics of this epoch to three separate effects: finite electron mass, finite-temperature quantum electrodynamic (QED) effects on the plasma equation of state, and Boltzmann neutrino energy transport. The ratio of neutrino to plasma-component energy scales manifests in Cosmic Microwave Background (CMB) observables, namely the baryon density and the radiation energy density, along with the primordial helium and deuterium abundances. Our results demonstrate how the treatment of in-medium electron mass (i.e., QED effects) could translate into an important source of uncertainty in extracting neutrino and beyond-standard-model physics limits from future high-precision CMB data.

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Neutrino quantum kinetic equations

Cited by 93 publications

References 93 publications

Incomplete neutrino decoupling effect on big bang nucleosynthesis

Incomplete neutrino decoupling effect on big bang nucleosynthesis

Effect of collisions on neutrino flavor inhomogeneity in a dense neutrino gas

Insights into neutrino decoupling gleaned from considerations of the role of electron mass

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