The Qweak experiment at Jefferson Laboratory made the first direct determination of the proton’s weak charge via a measurement of the parity-violating asymmetry in elastic electron-proton scattering at low four-momentum transfer. A longitudinally polarized electron beam was scattered off a liquid hydrogen target and detected in eight azimuthally symmetric fused silica detectors. The parity violation asymmetry was measured by observing the difference in rates seen in the detectors when the helicity of the electron beam was rapidly reversed. The commissioning run result was published in 2013, with a measured asymmetry of − 279 ± 35 ( stat ) ± 31 ( syst ) ppb. When combined with previous parity-violating electron scattering (PVES) data, we obtained a value for weak charge of proton, 0.064 ± 0.012, which agrees well with the prediction of Standard Model.

Over the past several years, “hidden sectors” have attracted a surge of interest in the particle physics community. I’ll summarize the underlying physics motivation and give an update on various search strategies. Most of the talk will focus on new bounds on dark sector models, emphasizing where Standard Model uncertainties still play a big part. In particular, we’ll examine bounds on "dark photons" from Supernova 1987A, where we have incorporated finite-temperature effects on the production and trapping for the first time, utilized a realistic model of the high-mixing parameter space, and shown the effect of systematic uncertainties from stellar progenitor models. Other hidden sector scenarios will be addressed as time permits.

The existence of dark matter is one of the few solid hints for physics beyond the standard model. If dark matter has indeed particle nature, then direct detection via scattering on atomic nuclei is one of the most promising discovery channels. In order to connect this nonrelativistic process with astrophysical and collider searches, as well as UV model building, a consistent setup of effective field theories for the different energy scales is necessary.

After an introduction to the physics of dark matter, I will present our work on the explicit connection between these energy scales, from the UV down to the nuclear scale, including a systematic error estimate. I will, in particular, discuss the effects of higher-order chiral and electroweak corrections.

Many of the Air Force Research Laboratory’s experimental efforts are focused on precision navigation and timing. The establishment and testing of an optical frequency standard is useful for numerous terrestrial and space based applications. Therefore, an optical atomic clock based upon a 778 nm two-photon transition in rubidium, is an excellent candidate to meet GPS-III frequency stability requirements, as commercial off-the-shelf components allow for a simple set-up that supports 7 x 10^-13 at 1 second.

The Nab collaboration proposes to measure the electron-neutrino correlation parameter a with a precision of δa/a = 10^−3 and the Fierz interference term b to δb = 3 × 10^−3 in unpolarized free neutron β decay. These results are expected to lead to a new, precise, independent determination of the ratio λ = GA/GV that will sensitively test CKM unitarity. A long asymmetric spectrometer guides the decay products to two large area silicon detectors in order to precisely determine the electron energy and proton momentum. The Nab apparatus is under installation on the Fundamental Neutron Physics Beamline at the SNS at ORNL and commissioning will begin in the near future. An overview of the Nab experiment, systematics effects associated with spectrometer magnetic fields, and the first tests of the spectrometer will be presented.

Neutron-induced failures in semiconductor devices are an increasing concern in the semiconductor industry. Neutrons are produced in the upper atmosphere by cosmic-ray bombardment of nuclei in the air. Because the neutrons are uncharged, they have long mean-free paths and can reach aircraft altitudes and below. Neutron interactions in semiconductor devices produce ionized recoils or reaction products that deposit charge in the vicinity of nodes and cause the devices to fail. These types of failures include bit flips, latchups, burnout etc. Many semiconductor companies have measured the system response at an accelerated rate by using the high-energy Los Alamos Neutron Science Center (LANSCE) spallation neutron source. The LANSCE source produces a neutron spectrum that is very similar in shape to the neutron spectrum produced by cosmic rays in the earth’s atmosphere but is approximately 108 times more intense than the sea-level neutron flux. This acceleration factor allows testing of semiconductor devices to measure their response, and to develop and test failure models and mitigation approaches.

Cosmic microwave background Stage-IV experiments and thirty-meter-class
telescopes will come on line in the next decade. The convolution of these data
sets will provide on order 1% precision for observables related to neutrino
cosmology. Beyond Standard Model (BSM) physics could manifest itself in slight
deviations from the standard predictions of quantities such as the neutrino
energy density and the primordial abundances from Big Bang Nucleosynthesis
(BBN). In this talk, I will argue for the need for precise and accurate
numerical calculations of BBN. I will first show the detailed evolution of the
neutrino spectra as they go out of equilibrium with the plasma. The spectra
are important in changing the ratio of neutrons to protons. I will show how
sensitive the primordial mass fraction of helium is to the weak interaction
rates which evolve the neutron-to-proton ratio. Finally, I will present an
example of how BSM physics can affect BBN by instituting an asymmetry between
neutrinos and antineutrinos, commonly characterized by a lepton number.

Because neutrinos are so penetrating, they allow a nearly-unobstructed view of the nuclear, particle and astrophysical processes occurring deep in the interiors of the Sun and stars. Already a spectacular object at optical wavelengths, a core-collapse supernova liberates 99% of its energy in the form of neutrinos of various flavors, each of which has a distinctive energy spectrum and time dependence. Neutrinos is where the action is! A neutrino detector constructed of lead would be primarily sensitive to the electron-type neutrinos from a supernova, and would complement the existing water Cerenkov and organic scintillator detectors which are sensitive primarily to electron anti-neutrinos. We have tentative ideas for a 1 kiloton lead detector at the Gran Sasso laboratory in Italy, as a successor to the much smaller HALO-1 detector now operating at SNOLAB in Canada. We would welcome new collaborators.