Speaker
Description
Neutrino experiments lie at the edge of the intensity frontier and
therefore can be exploited to search for new light particles weakly
coupled to the visible sector. In this work we derive new constraints on
axion-like particles (ALPs) using data from the MicroBooNE experiment,
from a search for e+e- pairs pointing in the direction of the NuMI
absorber. In particular, we consider the addition of higher-dimensional
effective operators coupling the ALP to the electroweak gauge bosons.
These would induce K-> π a from kaon decay at rest in the NuMI
absorber, as well as ALP decays into pairs of leptons or photons. We
discuss in detail and compare various results obtained for the decay
width K-> π a in previous literature. For the operator involving the
Higgs, MicroBooNE already sets competitive bounds (comparable to those
of NA62) for ALP masses between 100 and 200 MeV. We also compute the
expected sensitivities from the full NuMI dataset recorded at
MicroBooNE. Our results show that a search for a a-> ɣʹɣʹ signal
may be able to improve over current constraints from beam-dump
experiments on the operator involving the ALP coupling to the W.
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