A primary goal of the particle physics program is to discover the
connection between dark matter and the Standard Model.
EUSO-SPB2 will be sensitive to hypothetical dark-quark nuggets
that may strike the Earth's atmosphere. Elastic scattering allows
dark-quark nuggets and baryons to exchange momentum. If a dark-quark
nugget were to traverse the Earth's atmosphere its energy deposition
would excite the nitrogen molecules of air producing observables
signals at fluorescence detectors. The internal energy density of
standard nuggets of strange quark matter is fixed by QCD dynamics, but the internal energy density of dark-quark nuggets may span
several orders of magnitude depending on the confinement scale and
the magnitude of the dark baryon asymmetry [arXiv:1810.04360]. This opens up the
quark nuggets phase space into the EUSO-SPB2 sensitivity reach.
Listen to Tom Paul describing
the ins and outs of the footprints dark-quark nuggets could leave in
the Earth's atmosphere. For further details, see
arXiv:2104.05131.
ANITon Searches
The ANtarctic Impulsive Transient Antenna (ANITA) has observed two
anomalous events (nicknamed ANITons), which qualitatively look like upward going extensive
air showers initiated
by energetic (~500 PeV) particles that emerge from the ice
along trajectories with large elevation angles (~30 degrees above
the horizon) [arXiv:1603.05218, arXiv:1803.0588]. The ANITA Collaboration
immediately pointed out that the ANITons may originate in the atmospheric decay of an upgoing tau-lepton
produced through a charged current interaction of a tau neutrino inside
the Earth. However, for the angles inferred from ANITA observations,
the ice would be well screened from up-going high-energy neutrinos by
the underlying layers of Earth, challenging Standard Model
explanations [arXiv:1811.07261]. Although systematic effects of data analysis cannot yet be
completely discarded as the
possible origin of the ANITons, the door is open for
speculation. Listen to Luis Anchordoqui speculating about a possible ANITon
origin and how we can hunt for these exotic particles with EUSO-SPB2.
The speculation that ANITons originate in the two-body
decay of a quasi-stable heavy sterile neutrino (itself gravitationally
trapped inside the Earth) has now excluded at more than 95% CL by IceCube data
[arXiv:2107.01159].
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