Generalized perturbations in neutrino mixing

Abstract

We derive expressions for the neutrino mixing parameters that result from complex perturbations on (1) the Majorana neutrino mass matrix (in the basis of charged lepton mass eigenstates) and on (2) the charged lepton mass matrix, for arbitrary initial (unperturbed) mixing matrices. In the first case, we find that the phases of the elements of the perturbation matrix, and the initial values of the Dirac and Majorana phases, strongly impact the leading order corrections to the neutrino mixing parameters and phases. For experimentally compatible scenarios wherein the initial neutrino mass matrix has µ−τ symmetry, we find that the Dirac phase can take any value under small perturbations. Similarly, in the second case, perturbations to the charged lepton mass matrix can generate large corrections to the mixing angles and phases of the PMNS matrix. As an illustration of our generalized procedure, we apply it to a situation in which nonstandard scalar and nonstandard vector interactions simultaneously affect neutrino oscillations.

Erratum: Generalized mass ordering degeneracy in neutrino oscillation experiments [Phys. Rev. D 94 , 055005 (2016)]

“…Therefore, while the degeneracy is exact for ( ee , eτ ) = (−2, 0), it is recovered to a good accuracy for nonzero values of eτ as long as | eτ | 0.2| ee + 2|. The importance of ee and eτ for the mass ordering determination in DUNE has been pointed out recently in [23].…”

Hints for LeptonicCPViolation or New Physics?

“…The resulting degeneracies between New Physics and oscillation physics recently have been studied in Ref. [19] in a more general setting. Here, we will study specifically the impact neutral current-like NSI can have on the analysis of Daya Bay, T2K and NOvA data sets and point out that the current hint for maximal CP violation maybe in fact be caused by CP conserving New Physics.…”

Neutrino mass matrices with two vanishing elements/cofactors

“…Using the experimental constraints on the neutrino mixing angles supplemented with a large |M ee |, class B of TZ as well as TC predict near maximal atmospheric mixing angle θ 23 and Dirac-type CP-violating phase δ fixed near This feature has not been discussed in Ref. [33] while considering the indistinguishable nature of these texture structures. This distinction, in fact, becomes clearer if the texture structures under investigation are subjected to the experimental inputs of neutrino mixing angles θ 12 , θ 23 along with m 2 21 , m 2 31 , and large |M ee |, while allowing θ 13 to vary between 0 • -12 • .…”

“…The indistinguishability of TZ and TC has been studied in [13]. Recently, Liao et al [33] have discussed the indistinguishability of the B 1 (B 2 ) class of TZ and the B 6 (B 5 ) class of TC with opposite mass hierarchy, respectively. Their analysis claims similar predictions for the oscillation parameters and Majorana phases, which means that if the mass hierarchy is not known the textures B 1 (B 2 ) of TZ and B 6 (B 5 ) of TC are indistinguishable but the results obtained earlier in [7,13] seem to distinguish the TZ and TC on the basis of the quadrant of δ.…”

“…[7,13]. After the confirmation of relatively large value of θ 13 , these texture structures have been further checked for their viability and predictions for the unknown neutrino parameters like δ, Majorana phases, and neutrino mass scale [25][26][27][28][29][30][31][32]. The indistinguishability of TZ and TC has been studied in [13].…”