Constraining astrophysical neutrino flavor composition from leptonic unitarity

Xu, Xun-Jie; He, H.; Rodejohann, Werner

doi:10.1088/1475-7516/2014/12/039

Cited by 36 publications

(41 citation statements)

References 68 publications

(149 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, the TBM ordering P ee > {P µµ , P µτ , P τ τ } > {P eµ , P eτ } (i.e., 1 > a + b + c, and c > a or b) is maintained in the real world. This ordering result will be an important ingredient in establishing 1 We note that unitarity relations were recently presented in detail in [9]. Our simple constraints here are equivalent to two of the three unitarity results obtained there.…”

Section: Perturbations About Tbm Values and Flavor Trianglessupporting

confidence: 71%

Aspects of the flavor triangle for cosmic neutrino propagation

Fu¹,

Ho²,

Weiler³

2015

Phys. Rev. D

View full text Add to dashboard Cite

Over cosmic distances, astrophysical neutrino oscillations average out to a classical flavor propagation matrix P. Thus, flavor ratios injected at the cosmic source W e , W µ , W τ evolve to flavor ratios at Earthly detectors w e , w µ , w τ according to w = P W . The unitary constraint reduces the Euclidean octant to a "flavor triangle". We prove a theorem that the area of the Earthly flavor triangle is proportional to Det(P). One more constraint would further reduce the dimensionality of the flavor triangle at Earth (two) to a line (one).We discuss four motivated such constraints. The first is the possibility of a vanishing determinant for P.We give a formula for a unique δ(θ ij 's) that yields the vanishing determinant. Next we consider the thinness of the Earthly flavor triangle. We relate this thinness to the small deviations of the two angles θ 32 and θ 13 from maximal mixing and zero, respectively. Then we consider the confusion resulting from the tau neutrino decay topologies, which are showers at low energy, "double-bang" showers in the PeV range, and a mixture of showers and tracks at even higher energies. We examine the simple low-energy regime, where there are just two topologies, w shower = w e + w τ and w track = w µ . We apply the statistical uncertainty to be expected from IceCube to this model. Finally, we consider ramifications of the expected lack of ν τ injection at cosmic sources. In particular, this constraint reduces the Earthly triangle to a boundary line of the triangle. Some tests of this "no ν τ injection" hypothesis are given.PACS numbers: 14.60. Pq, 95.55.Vj, 95.85.Ry

show abstract

Section: Perturbations About Tbm Values and Flavor Trianglessupporting

confidence: 71%

Aspects of the flavor triangle for cosmic neutrino propagation

Fu¹,

Ho²,

Weiler³

2015

Phys. Rev. D

View full text Add to dashboard Cite

show abstract

“…The unitarity of the new mixing matrix allows us to compute the boundary of the region that encloses all possible flavor compositions at the Earth, in spite of not knowing the values of the matrix elements. Previous work [20] derived a set of unitarity bounds for specific choices of flavor com- The corresponding open symbols indicate the expected composition at Earth under standard oscillations using the best-fit mixing parameters for normal mass ordering [9]. We include the best-fit flavor composition from IceCube [10] as a black star and the 68% and 95% confidence levels as grey-shaded areas.…”

Section: Introductionmentioning

confidence: 99%

Unitarity bounds of astrophysical neutrinos

Ahlers

Bustamante

2018

Phys. Rev. D

View full text Add to dashboard Cite

The flavor composition of astrophysical neutrinos observed at neutrino telescopes is related to the initial composition at their sources via oscillation-averaged flavor transitions. If the time evolution of the neutrino flavor states is unitary, the probability of neutrinos changing flavor is solely determined by the unitary mixing matrix that relates the neutrino flavor and propagation eigenstates. In this paper we derive general bounds on the flavor composition of TeV-PeV astrophysical neutrinos based on unitarity constraints. These bounds are useful for studying the flavor composition of high-energy neutrinos, where energy-dependent nonstandard flavor mixing can dominate over the standard mixing observed in accelerator, reactor, and atmospheric neutrino oscillations.

show abstract

“…Various authors have studied the implications of IceCube's HESE (high-energy starting-event) topologies with astrophysical and/or exotic production mechanisms [85,86,87,88,89,90,91,92]. Figure 11 shows the general neutrino flavor phase space ν e :ν µ :ν τ and the expected intrinsic flavor ratio in astrophysical sources from neutron decay (triangle), pion+muon decay (circle), and muondamped pion decay (square).…”

Section: Conventional Atmosphericmentioning

confidence: 99%

The Successful Story of Neutrino Telescopes

Halzen¹

2016

Proceedings of XVI International Workshop on Neutrino Telescopes — PoS(NEUTEL2015)

View full text Add to dashboard Cite

We review the rationale for building kilometer-scale neutrino detectors and briefly describe the first such instrument, IceCube. It has transformed one cubic kilometer of natural Antarctic ice into a Cherenkov detector that maps the light patterns radiated by the secondary particles produced in neutrino interactions. We discuss the discovery of cosmic neutrinos and reappraise the properties of the flux after the recent doubling of the data from two to four years. We conclude that the flux is isotropic with a flavor composition of 1:1:1 and therefore most likely extragalactic in origin. It is large by any measure and consistent with a neutrino flux from sources that release a similar amount of energy in photons and, possibly, cosmic rays. Strikingly, the photon flux accompanying IceCube neutrinos is, after cascading through the extragalactic background light, consistent with the high-energy gamma-ray flux observed by Fermi. This observation suggests common sources, which should ease the task of identifying the cosmic accelerators producing IceCube neutrinos. We will argue that event rates of hundreds rather than tens per year are desirable for launching a new era of astronomy. Building a detector that instruments ten cubic kilometers of ice is realistic and, as a result of the large absorption length of the ice revealed by IceCube, comparable in scope to the original project.

show abstract

Constraining astrophysical neutrino flavor composition from leptonic unitarity

Cited by 36 publications

References 68 publications

Aspects of the flavor triangle for cosmic neutrino propagation

Aspects of the flavor triangle for cosmic neutrino propagation

Unitarity bounds of astrophysical neutrinos

The Successful Story of Neutrino Telescopes

Contact Info

Product

Resources

About