The light neutrino mass hierarchy is not known yet. This is because for one of the two independent mass-squared differences only the absolute value is known.

Is there a way that in future the hierarchy will be determined? Is there any experiment which proposes to determine the hierarchy? If yes, which experiment and how?

  • $\begingroup$ Several experiments. Did you look at Hyperkamiokande? $\endgroup$ – Cosmas Zachos Dec 15 '17 at 15:10
  • $\begingroup$ In addition to oscillations, beta decay experiments like KATRIN and Project 8 may be able to rule out the inverted hierarchy if they can establish that the emitted neutrinos have a mass below ~0.04eV. KATRIN should be sensitive down to ~0.2eV, while the future Phase IV of Project 8 aims to reach that 0.04eV target. $\endgroup$ – David Schaich Dec 15 '17 at 19:33
  • $\begingroup$ The smart money is arguing for NOvA, see fig 36 here, within 2 yrs. $\endgroup$ – Cosmas Zachos Dec 15 '17 at 19:54

Your question is magnificently broad. The outstanding review of the searches by Qian and Vogel 2015 covers all bases and all dozen experiments and alternate pathways/techniques.

  • Accelerator Neutrinos:Appearance

  • Atmospheric neutrinos

  • ReactorAntineutrinos

They combine all extant data from all experiments, and not one narrow gimmick which you might be seeking. But I have no sense of the schedules and luck involved in getting there first.

Listening to people around me, they appear to think that by 2020 we'll know for sure from NOνA, enter image description here but I'm not sure this is not geographical bias.

PS. Purists insist on calling this 123 vs 312 option choice the "Mass ordering" issue rather than "Mass hierarchy", but I'll be damned if I know why... (I may be at a linguistic disadvantage, there. They predicate "hierarchy" on the value of the lightest neutrino mass.)


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