Equilibration of quantum many-body fast neutrino flavor oscillations

Journal Article · 07 December 2023 · Physical Review. D.

DOI: https://doi.org/10.1103/physrevd.108.123010 · OSTI ID:2228985

Martin, Joshua D.  ^[1]; Neill, Duff ^[1]; Roggero, A.  ^[2]; Duan, Huaiyu  ^[3]; Carlson, J. ^[1]

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1. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
2. University of Trento (Italy); INFN-TIFPA Trento Institute of Fundamental Physics and Applications (Italy)
3. University of New Mexico, Albuquerque, NM (United States)

Neutrino gases are expected to form in high-density astrophysical environments, and accurately modeling their flavor evolution is critical to understanding such environments. In this work, we study a simplified model of such a dense neutrino gas in the regime for which neutrino-neutrino coherent forward scattering is the dominant mechanism contributing to the flavor evolution. We show evidence that the generic potential induced by this effect is nonintegrable and that the statistics of its energy level spaces are in good agreement with the Wigner surmise. We also find that individual neutrinos rapidly entangle with all of the others present, which results in an equilibration of the flavor content of individual neutrinos. We show that the average neutrino flavor content can be predicted utilizing a thermodynamic partition function. A random phase approximation to the evolution gives a simple picture of this equilibration. In the case of neutrinos and antineutrinos, processes like v_ev_e ⇌ v_μv_μ yield a rapid equilibrium satisfying n(v_e)n(v_e) = n(v_μ)n(v_μ) = n(v_τ)n(v_τ) in addition to the standard lepton number conservation in regimes where off-diagonal vacuum oscillations are small compared to v – v interactions.

• Research Organization: Univ. of New Mexico, Albuquerque, NM (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR); USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: SC0017803; AC52-06NA25396; 89233218CNA000001
• OSTI ID: 2228985
• Alternate ID(s): OSTI ID: 2371040; OSTI ID: 2406569
• Report Number(s): LA-UR-23-28635; TRN: US2500239
• Journal Information: Physical Review. D., Vol. 108, Issue 12; ISSN 2470-0010
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English