Resonant electromagnetic leptogenesis with coherent heavy-neutrino evolution

Abstract

We study TeV-scale electromagnetic leptogenesis generated by the gauge-invariant neutrino-dipole operators $O_{NB}$ and $O_{NW}$. The benchmark Wilson coefficients are specified at the renormalization scale ${\kappa }_N=M_1=1\mathrm{TeV}$ and related to their values at ${\kappa }_{\mathrm{match}}=3\mathrm{TeV}$ through the coupled one-loop $\nu$SMEFT evolution. The collision network contains the symmetric-phase $1\leftrightarrow 3$ and crossed $2\leftrightarrow 2$ processes generated by the linear field-strength vertices and the VEV-induced two-body $\gamma$, $Z$, and $W$ channels through the electroweak crossover. We use a factorized leading-moment, momentum-averaged Markovian treatment for two $2\times 2$ heavy-flavor density matrices, one for each helicity. Pole-resummed two-state effective couplings enter the lepton and antilepton collision tensors, while the off-diagonal density matrices describe coherent evolution and collision damping. Three resolved flavor charges are coupled to a finite-rate sphaleron equation, yielding the frozen baryon yield $Y_B^{\mathrm{FO}}$. For the benchmark ${\tilde{m}}_1^{\mathrm{EM}}=3.97\times 10^{-2}\mathrm{eV}$, the decay-only pole prescription, in which only decay contributions enter the absorptive pole matrix, gives the locally optimized positive near-resonant maximum $Y_B^{\mathrm{FO}}=+5.50\times 10^{-5}$ at $\Delta M=1.29\times 10^{-11}\mathrm{GeV}$. Adding the thermally averaged crossed-scattering moment to the pole matrix defines the decay-plus-scattering prescription and shifts the maximum to $Y_B^{\mathrm{FO}}=+8.44\times 10^{-5}$ at $\Delta M=1.83\times 10^{-11}\mathrm{GeV}$. The corresponding signed mass-splitting curves cross the observed value $Y_B^{\mathrm{obs}}$ at $\Delta M=1.68\times 10^{-5}\mathrm{GeV}$ and $2.34\times 10^{-5}\mathrm{GeV}$.

Comments: 7 pages, 3 figures