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DOE OSTI2023

Measuring the Migdal effect in semiconductors for dark matter detection

The Migdal effect has received much attention from the dark matter direct detection community, in particular due to its power in setting leading limits on sub-GeV particle dark matter. However, it is crucial to obtain experimental confirmation of the Migdal effect through nuclear scattering using Standard Model probes. In this work, we extend existing calculations of the Migdal effect to the case of neutron-nucleus scattering, with a particular focus on neutron scattering angle distributions in silicon. We identify kinematic regimes wherein the assumptions present in current calculations of the Migdal effect hold for neutron scattering and demonstrate that these include viable neutron calibration schemes. We then apply this framework to propose an experimental strategy to measure the Migdal effect in cryogenic silicon detectors using an upgrade to the NEXUS facility at Fermilab.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Gravitational production of spin-3/2 particles during reheating

We compute the density of a spin-$\frac{3}{2}$ particle, the raritron, produced at the end of inflation due to gravitational interactions. We consider a background inflaton condensate as the source of this production, mediated by the exchange of a graviton. This production greatly exceeds the gravitational production from the emergent thermal bath during reheating. The relic abundance limit sets an absolute minimum mass for a stable raritron, though there are also model-dependent constraints imposed by unitarity. We also examine the case of gravitational production of a gravitino, taking into account the goldstino evolution during reheating. We compare these results with conventional gravitino production mechanisms.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Nucleon isovector axial form factors

We present results for the isovector axial vector form factors obtained using thirteen 2 + 1 + 1 -flavor highly improved staggered quark (HISQ) ensembles generated by the MILC collaboration. The calculation of nucleon two- and three-point correlation functions has been done using Wilson-clover fermions. In the analysis of these data, we quantify the sensitivity of the results to strategies used for removing excited state contamination and invoke the partially conserved axial current relation between the form factors to choose between them. Our data driven analysis includes removing contributions from multihadron N π states that make significant contributions. Our final results are g A = 1.292 ( 53 ) stat ( 24 ) sys for the axial charge; g S = 1.085 ( 50 ) stat ( 103 ) sys and g T = 0.991 ( 21 ) stat ( 10 ) sys for the scalar and tensor charges; ⟨ r A 2 ⟩ = 0.439 ( 56 ) stat ( 34 ) sys fm 2 for the mean squared axial charge radius, g P * = 9.03 ( 47 ) stat ( 42 ) sys for the induced pseudoscalar charge; and g π N N = 14.14 ( 81 ) stat ( 85 ) sys for the pion-nucleon coupling. We also provide a parametrization of the axial form factor G A ( Q 2 ) over the range 0 ≤ Q 2 ≤ 1 GeV 2 for use in phenomenology and a comparison with other lattice determinations. We find that the various lattice data agree within 10% but are significantly different from the extraction of G A ( Q 2 ) from the ν -deuterium scattering data. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗