Neutrino asymmetry evolution + BBN | Public grids

Datasets associated to “Constraints on primordial lepton asymmetries with full neutrino transport”, J. Froustey and C. Pitrou.

We solve the neutrino Quantum Kinetic Equations with the full collision term in the range of temperatures [25 MeV, 0.006 MeV], in order to get the evolution of neutrino distributions. We explore a range of primordial neutrino asymmetries, whose evolution results from a complicated interplay between the Hamiltonian terms (in particular, the self-interaction mean-field) and collisions. The output of this neutrino calculation is used in the Big Bang nucleosynthesis code PRIMAT to determine the primordial abundances obtained in this cosmological scenario.

The datasets are respectively:

NEVO_PRIMAT_grid_equalxi.csv, used in Section IV.A ;

NEVO_PRIMAT_grid_xiav_xie.csv, used in Section IV.B ;

NEVO_PRIMAT_grid_ximu_xitau.csv, used in Section IV.C ;

NEVO_PRIMAT_grid_xiav_xie_zoom.csv, used in Section V ;

NEVO_PRIMAT_grid_3D.csv, an additional grid exploring the full 3D parameter space (xi_e,xi_mu,xi_tau).

Each dataset has the same format, with 21 columns identified in the header of each file:

xit_av, average of the initial xitilde (= xi + xi^3/pi^2)

xit_e - xit_av, initial difference between the e flavor xitilde and the average

(xit_mu - xit_tau)/2, also called \tilde{Delta}, difference between the mu and tau flavor initial asymmetries

xi_e, reduced initial chemical potential of nu_e (opposite one for nu_ebar)

xi_mu

xi_tau

N_eff, effective number of neutrino species after decoupling (i.e., for T = 0.006 MeV)

Y_He4, primordial helium-4 abundance obtained from PRIMAT (with omega_baryon = 0.02242)

D/H, primordial deuterium abundance obtained from PRIMAT (with omega_baryon = 0.02242)

d[ln(Y_He4)]/d[ln(omega_b)] = dY, relative derivative such that Y_He4(omega) = Y_He4^ref * (1+dY*(omega-omega^ref)/omega^ref)

d[ln(D/H)]/d[ln(omega_b)], same for D/H

eta^f_e, final electron flavor asymmetry, defined as eta_e = (n_nue - n_nuebar)/Tcm^3

eta^f_mu, final muon flavor asymmetry

eta^f_tau, final tau flavor asymmetry

eta^f_1, final asymmetry of the nu_1 mass eigenstate

eta^f_2, final asymmetry of the nu_2 mass eigenstate

eta^f_3, final asymmetry of the nu_3 mass eigenstate. These "mass asymmetries" are determined using the fact that the final density matrix is diagonal in the mass basis, which allows to relate {eta_alpha}_(flavor) to {eta_i}_(mass). Note that we take the mean values of each mixing parameter from the Particle Data Group (2023), neglecting the CP-phase.

rho^f_e, final comoving energy density of nu_e + nu_ebar

rho^f_mu, final comoving energy density of nu_mu + nu_mubar

rho^f_tau, final comoving energy density of nu_tau + nu_taubar

z^f, final dimensionless photon temperature (z = T_gamma/T_cm)