A new generation of experiments taking advantage of the upgraded electron beam facility at Jefferson Laboratory aims to explore the three-dimensional partonic structure of the proton with unprecedented precision. One of those is the CEBAF Large Acceptance Spectrometer (CLAS12), where semi-inclusive deep-inelastic scattering (SIDIS) events can be detected over a wide kinematic range. In SIDIS events, the incoming electron scatters off a quark in the proton which subsequently hadronizes into a detected final state. The quantum numbers of the hadronic final state are correlated to the quantum numbers of the parent quark and can therefore be used to extract information about the partonic content of the nucleon. Arguably, most information about parton distribution functions has been extracted from final states, where a single, spinless hadron such as a pion or kaon has been detected. Using more complex final states that can carry angular momentum quantum numbers, such as hadron-pairs or polarized hyperons, allows access to spin orbit correlations the hadronization process and a more targeted access to complex dynamics inside the proton. This talk will discuss di-hadron channels to extract parton distributions from SIDIS data taken at CLAS12 as well as the measurement of the corresponding fragmentation functions (FFs). Fragmentation functions describe the formation of hadrons from quarks and can be measured in e+e- annihilation. Here measurements of di-hadron and polarized lambda FFs at the B-factory Belle will be discussed

The only practical way to experimentally verify the nature of neutrinos is via the observation of neutrinoless double-beta decay. EXO-200, the first current generation neutrinoless double-beta decay searches to begin taking data, wrapped up data taking at the end of last year. While the final results to be presented by EXO-200 will continue to advance the field, EXO-200 has long since served its primary mission as a prototype for a tonne scale next generation search: nEXO. I intend to impress you with the success of EXO-200 and build on this to convince you that nEXO has every chance of observing neutrinoless double-beta decay while being the most likely to achieve the best sensitivity of proposed next generation searches.

Measurements of the neutron electric dipole moment (nEDM) are currently of considerable experimental interest due to their high probability of being able to discover new physics within and beyond the Standard Model in the next generation of experiments.   The current upper limit of the nEDM of 3e-26 ecm and the next generation of experiment plan to improve on this by making measurements that are up by up to two orders of magnitude more precise.  One of these next generation experiments is the SNS nEDM experiment which will run at the Spallation Neutron Source in Tennessee.

The SNS nEDM experiment plans to calculate the nEDM by measuring the change in the difference of the precession frequencies of polarized neutrons and helium-3 that coexist together in a uniform magnetic field when a strong electric field is reversed.  To maintain the helium-3 polarization as it is transported from the beam source to the measurement cell a complex series of magnets are required.  I will discuss the design process of the magnets that starts with FEA simulation of the winding and the fields in Comsol Multiphysics, the creation of a CAD model from the simulation and how 3D printing can be used to prototype the magnets, as well as built the final magnet design.

What would happen if we were to compress the sun to the size of Lexington and then add a bit more mass? Would this object expand, contract, or stay the same size? Nuclear astrophysics research aims to answer this and other seemingly simple questions. This talk will focus on the nuclear physics of the outer layers of accreting neutron stars. I will show how properties of atomic nuclei impact dense matter constraints obtained for these objects. I will also discuss recent experimental work dedicated toward constraining properties of key nuclei.

The Muon g-2 experiment (E989) at Fermilab is aiming at measuring the anomalous magnetic moment of the muon (aμ) at a precision of ∼140 ppb. aμ was measured at a precision of 540 part-per-billion (ppb) in the previous Muon g-2 experiment (E821), and its result deviated from the theoretical calculation by ∼3.7σ. This discrepancy is arguably the strongest existing hint for physics beyond the SM. The new experiment E989 will either confirm or resolve it. In this experiment, the muon anomalous precession angular frequency ωa and the magnetic field in which the muon precesses are measured. ωa is measured by detecting the decay positrons in 24 calorimeter stations, and the magnetic field is measured by Nuclear Magnetic Resonance (NMR) probes. In this seminar, I will give a detailed description of the high precision magnetic field measurement system and its analysis framework. The NMR frequency extraction methods and their implementation using GPU for fast online feedback will be highlighted. The overall performance of the magnetic field measurement system in Run1 and recent upgrades for Run2 will be discussed.

Host: Prof. Tim Gorringe

I will review the concept of a Lifshitz point, and its possible relevance to the phase diagram of QCD, especially in contrast to the standard paradigm of a critical endpoint. I will stress on how fluctuations dramatically alter the phase diagram, yielding a Lifshitz regime. Possible signatures in heavy ion collisions are discussed.

Host: Ivan Horvath

The CP violating effects observed thus far appear only in flavor-changing processes and in a manner consistent with the predictions of the Standard Model (SM). The observed baryon asymmetry of the universe suggests that new mechanisms of CP violation beyond the SM should appear. Most searches for new sources of CP violation focus on processes that break P and CP, whereas processes that would break C and CP are not well studied. The decay η →π+ π- π0 is an ideal process in which to search for C and CP violation. In this talk, I will analyze the C and CP violating patterns in the Dalitz plot distribution of η → π+ π- π0decay and discuss the implications of existing experiments.

Host: Susan Gardner

Dark Matter (DM) provides strong evidence for physics beyond the Standard Model (SM). Arguably, rather than suggesting a specific mass scale for New Physics, it may point to a dark sector, weakly-coupled to the SM, as hinted at by the comparable abundances of dark matter and visible baryons. In the past few years, a program of new experiments has expanded DM searches far beyond the WIMP paradigm to include new hidden forces and matter. While this program has made impressive progress, there are considerable challenges that must be overcome to fully explore the viable dark sector scenarios over a wide range of mass scales. In this seminar, I will discuss new search strategies to test dark sectors at low-energy high-intensity experiments, with a special emphasis on existing and planned experiments at Fermilab. I will highlight the complementarity of these experiments with LHC searches and with DM direct and indirect detection experiments in probing the parameter space of well motivated models as, for example, models of Strongly Interacting Dark Matter or Inelastic Dark Matter.

Dark Matter (DM) provides strong evidence for physics beyond the Standard Model (SM). Arguably, rather than suggesting a specific mass scale for New Physics, it may point to a dark sector, weakly-coupled to the SM, as hinted at by the comparable abundances of dark matter and visible baryons. In the past few years, a program of new experiments has expanded DM searches far beyond the WIMP paradigm to include new hidden forces and matter. While this program has made impressive progress, there are considerable challenges that must be overcome to fully explore the viable dark sector scenarios over a wide range of mass scales. In this seminar, I will discuss new search strategies to test dark sectors at low-energy high-intensity experiments, with a special emphasis on existing and planned experiments at Fermilab. I will highlight the complementarity of these experiments with LHC searches and with DM direct and indirect detection experiments in probing the parameter space of well motivated models as, for example, models of Strongly Interacting Dark Matter or Inelastic Dark Matter.

There exists a class of ultralight Dark Matter (DM) models which could form a Bose-Einstein condensate (BEC) in the early universe and behave as a single coherent wave instead of individual particles in galaxies. We show that a generic BEC DM halo intervening along the line of sight of a gravitational wave (GW) signal could induce an observable change in the speed of GW, with the effective refractive index depending only on the mass and self-interaction of the constituent DM particles and the GW frequency. Hence, we propose to use the deviation in the speed of GW as a new probe of the BEC DM parameter space. With a multi-messenger approach to GW astronomy and/or with extended sensitivity to lower GW frequencies, the entire BEC DM parameter space can be effectively probed by our new method in the near future.