Combining Pumping and Absorption Effects in Neutrino Oscillation Probabilities: A Non-Hermitian Framework
Abstract
We study two-flavour neutrino oscillations in which a coherent off-diagonal interaction from a complex background field coexists with an absorptive channel acting on a single mass eigenstate. Since the two do not commute, the effective Hamiltonian is non-normal and oscillations and damping no longer factorise. We formulate the dynamics both as the no-jump sector of a Lindblad evolution and through biorthogonal diagonalisation, and obtain the evolution operator of our model in closed form. The model interpolates between quasi-global damping, standard invisible decay, and a critical point with polynomial-times-exponential evolution; for initially pure states it describes norm loss rather than decoherence. Comparing neutrinos and antineutrinos in the same background, with the mixing phase ϕ reversed and the background phase δ fixed, we derive closed-form CP, CPT and T asymmetries. The CPT asymmetries arise only from this phase assignment. In contrast, the T asymmetry, which is forbidden in unitary two-flavour oscillations, is independent of the prescription: it arises only through the non-normal structure, is proportional to the absorptive coupling, and vanishes only when δ+ϕ=nπ. For equal initial populations the net neutrino--antineutrino asymmetry vanishes identically, while a non-zero flavour asymmetry survives and requires a non-normal Hamiltonian.
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BibTeX
@misc{barenboim2026combining,
title = {{Combining Pumping and Absorption Effects in Neutrino Oscillation Probabilities: A Non-Hermitian Framework}},
author = {Gabriela Barenboim and Alberto Gago and Eduardo Massoni},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.27091},
eprint = {2610.27091},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.27091},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Combining Pumping and Absorption Effects in Neutrino Oscillation Probabilities: A Non-Hermitian Framework
AU - Gabriela Barenboim
AU - Alberto Gago
AU - Eduardo Massoni
PY - 2026
DA - 2026/10/19
PB - arXiv
DO - 10.48550/arxiv.2610.27091
UR - https://arxiv.org/abs/2610.27091
AB - We study two-flavour neutrino oscillations in which a coherent off-diagonal interaction from a complex background field coexists with an absorptive channel acting on a single mass eigenstate. Since the two do not commute, the effective Hamiltonian is non-normal and oscillations and damping no longer factorise. We formulate the dynamics both as the no-jump sector of a Lindblad evolution and through biorthogonal diagonalisation, and obtain the evolution operator of our model in closed form. The model interpolates between quasi-global damping, standard invisible decay, and a critical point with polynomial-times-exponential evolution; for initially pure states it describes norm loss rather than decoherence. Comparing neutrinos and antineutrinos in the same background, with the mixing phase ϕ reversed and the background phase δ fixed, we derive closed-form CP, CPT and T asymmetries. The CPT asymmetries arise only from this phase assignment. In contrast, the T asymmetry, which is forbidden in unitary two-flavour oscillations, is independent of the prescription: it arises only through the non-normal structure, is proportional to the absorptive coupling, and vanishes only when δ+ϕ=nπ. For equal initial populations the net neutrino--antineutrino asymmetry vanishes identically, while a non-zero flavour asymmetry survives and requires a non-normal Hamiltonian.
ER -