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SUMMARY:Disentangling genuine from matter-induced CP violation in neutrino
oscillations
DTSTART;VALUE=DATE-TIME:20181127T123000Z
DTEND;VALUE=DATE-TIME:20181127T125500Z
DTSTAMP;VALUE=DATE-TIME:20191210T140523Z
UID:indico-contribution-3139761@indico.cern.ch
DESCRIPTION:Speakers: Alejandro Segarra (IFIC (CSIC\, Univ. Valencia))\nWe
prove that\, in any flavor transition\, neutrino oscillation CP violating
asymmetries in matter have two disentangled components: (a) a CPT-odd T-i
nvariant term\, non-vanishing iff there are interactions with matter\; (b)
a T-odd CPT-invariant term\, non-vanishing iff there is genuine CP violat
ion. As function of the baseline\, these two terms are distinct L-even and
L-odd observables\, respectively. In the experimental region of terrestri
al accelerator neutrinos\, we calculate their approximate expressions from
which we prove that\, at medium baselines\, the CPT-odd component is smal
l and nearly $\\delta$-independent\, so it can be subtracted from the expe
rimental CP asymmetry as a theoretical background\, provided the hierarchy
is known. At long baselines\, on the other hand\, we find that (i) a Hier
archy-odd term in the CPT-odd component dominates the CP asymmetry for ene
rgies above the first oscillation node\, and (ii) the CPT-odd term vanishe
s\, independent of the CP phase $\\delta$\, at $E =0.92~\\mathrm{GeV}\\\,(
L/1300~\\mathrm{km})$ near the second oscillation maximum\, where the T-od
d term is almost maximal and proportional to $\\sin\\delta$. A measurement
of the CP asymmetry in these energy regions would thus provide separate i
nformation on (i) the neutrino mass ordering\, and (ii) direct evidence of
genuine CP violation in the lepton sector.\n\nhttps://indico.cern.ch/even
t/732911/contributions/3139761/
LOCATION:Sitzungssaal
URL:https://indico.cern.ch/event/732911/contributions/3139761/
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