Long-range neutrino interaction paper picked as PRL Editors’ Suggestion


Our paper ‘Universe’s Worth of Electrons to Probe Long-Range Interactions of High-Energy Astrophysical Neutrinos’ was published on Physical Review Letters:


It was selected as a PRL Editors’ Suggestion.  You can read the synopsis on the APS Physics page here:

Synopsis: Neutrino Probes of Long-Range Interactions

Link to the arXiv version of the paper: 1802.02042

Recovering the neutrino flavor composition at neutrino sources


In a new paper with Markus Ahlers, we introduce a method to infer the flavor composition of high-energy astrophysical neutrinos at their sources, based on measurements of the flavor composition at Earth:

Inferring the flavor of high-energy astrophysical neutrinos at their sources
Mauricio Bustamante, Markus Ahlers

To do this, we effectively revert the effect of flavor oscillations, while taking into account uncertainties in the neutrino mixing parameters.

We apply the method to flavor measurements published by IceCube, and to projections for the near-future IceCube upgrade and the more distant IceCube-Gen2.

In the illustrative, physically motivated case where there is no production of tau neutrinos at the sources, we can recover the fraction of electron neutrinos produced at the sources:


Presently (“IceCube 2015”), we find that neutrino production by the decay of high-energy pions is compatible with the flavor and oscillation data, with a slight preference for sources harboring strong magnetic fields which make intermediate muons lose energy by synchrotron radiation.  In the future, the IceCube ugprade and IceCube-Gen2 have the potential to single out the neutrino production mechanism


Unitarity bounds of astrophysical neutrinos


At high energies, new physics might affect the flavor composition of astrophysical neutrinos.  In a large class of new-physics models, the total number of neutrinos of all flavors is conserved.  In other words, the connection between the neutrino flavor states and the neutrino propagation states is represented by a unitary mixing matrix, whose elements have unknown or weakly bounded values.  The new physics is expected to affected the flavor composition of high-energy astrophysical neutrinos, possibly significantly.

In a new paper, led by Markus Ahlers, we show that it is not necessary to know the values of the elements of the new mixing matrix in order to map the effect of new physics on the flavor composition.  Based solely on the unitary of the new matrix, we derive the boundaries of regions that enclose all of the possible flavor compositions expected at Earth.


The regions we derive are refined and generalized versions of earlier work [X.-J. Xu, H.-J. He, and W. Rodejohann, JCAP 1412 (2014) 039, arXiv:1407.3736], and presented in a streamlined formalism that is easy to use.  Neutrino telescopes such as IceCube could adopt these regions as priors in their searches for new physics in the flavor composition.

Read the preprint here:

Unitarity Bounds of Astrophysical Neutrinos, 1810.00893
Markus Ahlers, Mauricio Bustamante, Siqiao Mu