Collective neutrino-antineutrino oscillations in dense neutrino environments?

Abstract

The paradigm-changing possibility of collective neutrino-antineutrino oscillations was recently advanced in analogy to collective flavor oscillations. However, the amplitude for the backward scattering process <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>ν</a:mi><a:msub><a:mi mathvariant="bold">p</a:mi><a:mn>1</a:mn></a:msub></a:msub><a:msub><a:mover accent="true"><a:mi>ν</a:mi><a:mo stretchy="false">¯</a:mo></a:mover><a:msub><a:mi mathvariant="bold">p</a:mi><a:mn>2</a:mn></a:msub></a:msub><a:mo stretchy="false">→</a:mo><a:msub><a:mi>ν</a:mi><a:msub><a:mi mathvariant="bold">p</a:mi><a:mn>2</a:mn></a:msub></a:msub><a:msub><a:mover accent="true"><a:mi>ν</a:mi><a:mo stretchy="false">¯</a:mo></a:mover><a:msub><a:mi mathvariant="bold">p</a:mi><a:mn>1</a:mn></a:msub></a:msub></a:math> is helicity suppressed and vanishes for massless neutrinos, implying that there is no off-diagonal refractive index between <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:mi>ν</l:mi></l:math> and <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline"><n:mover accent="true"><n:mi>ν</n:mi><n:mo stretchy="false">¯</n:mo></n:mover></n:math> of a single flavor of massless neutrinos. For a nonvanishing mass, collective helicity oscillations are possible, representing de facto <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:mi>ν</r:mi><r:mo>−</r:mo><r:mover accent="true"><r:mi>ν</r:mi><r:mo stretchy="false">¯</r:mo></r:mover></r:math> oscillations in the Majorana case. However, such phenomena are suppressed by the smallness of neutrino masses as discussed in the previous literature. Published by the American Physical Society 2024

Topics & Concepts