Probing a low-mass <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>Z</mml:mi><mml:mo>′</mml:mo></mml:msup></mml:math> gauge boson at IceCube and prospects for IceCube-Gen2

In this work, we investigate the impact of the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>L</a:mi><a:mi>μ</a:mi></a:msub><a:mo>−</a:mo><a:msub><a:mi>L</a:mi><a:mi>τ</a:mi></a:msub></a:math> model, which predicts a new massive gauge boson <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msup><c:mi>Z</c:mi><c:mo>′</c:mo></c:msup></c:math> on astrophysical neutrino events at the IceCube Observatory. This new gauge boson couples with leptons from the second and third families and would break the power law of the astrophysical neutrino flux due to the interaction of this flux with the cosmic neutrino background. We derive the sensitivity of IceCube to this model considering the high-energy start events data from 12 years of observation by assuming different assumptions for the redshift distributions of astrophysical neutrino sources, mass ordering, and sum of neutrino masses. Our results indicate that the current IceCube data are able to probe small coupling and masses on the order of some few MeV, with the covered parameter space being larger if a distribution of neutrino sources is described by the star formation rate model. In addition, we demonstrate that IceCube-Gen2 will cover a large region of the parameter space and will allow us to improve our understanding of the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msub><e:mi>L</e:mi><e:mi>μ</e:mi></e:msub><e:mo>−</e:mo><e:msub><e:mi>L</e:mi><e:mi>τ</e:mi></e:msub></e:math> model.