For a discrete symmetry that is anomalous under QCD, the domain walls produced in the early universe from its spontaneous breaking can naturally annihilate due to QCD instanton effects. We point out that the QCD phase transition within some domains with an effective large QCD theta angle could be a first-order one. This class of domain-wall models predicts an interesting gravitational wave spectroscopy with frequencies spanning more than ten orders of magnitude, from nanohertz to 100 Hz.

Neutron beta decay provides a sensitive means to uncover the details of the weak interaction by evaluating the ratio of axial-vector to vector coupling constants in the standard model, λ = GA/GV , through multiple decay correlations. The Nab experiment at the SNS in ORNL will make precise measurements of the electron-neutrino correlation parameter a and the Fierz interference term b in unpolarized free neutron beta decay. These results aim to deliver an independent determination of λ that will sensitively test CKM unitarity, as well as probe exotic electroweak scalar and tensor currents. Nab utilizes the world’s largest cryogen-free superconducting magnet spectrometer to guide the decay products to two large-area silicon detectors in order to precisely determine the electron energy and proton momentum. The Nab apparatus is being commissioned with more data to be taken soon. We will present an overview and updates of the Nab experiment, including a discussion of some systematic studies and effects we are working on at EKU.

For a quantitative investigation on the time evolution of heavy thermal dark matter particles at and after thermal freeze-out, close-to-threshold processes need to be taken into account which have a large impact on the observed dark matter relic abundance.  Our aim is to study the recoil effect of kinetically equilibrated dark matter pairs in a thermal medium and compute the center-of-mass recoil corrections to the near-threshold observables in the laboratory frame within the framework of potential non-relativistic effective field theories at finite temperature.  For the considered hierarchy of energy scales, we highlight the relative corrections due the recoil on the present dark matter energy density.

Nonrelativistic bound states lie at the core of quantum physics,
permeating the fabric of nature across diverse realms, spanning particle
to nuclear physics, and from condensed matter to astrophysics. These
systems are pivotal in addressing contemporary challenges at the forefront
of particle physics. Characterized by distinct energy scales, they serve
as unique probes of complex environments. Historically, their
incorporation into quantum field theory was fraught with difficulty until
the emergence of nonrelativistic effective field theories (NREFTs).

In this talk, we delve into the construction of a potential NREFT
(pNREFT), a framework that directly tackles bound state dynamics
reimagining quantum mechanics from field theory.
Focusing on heavy quarkonia, pNRQCD facilitates systematic definitions and
precise calculations for high-energy collider
observables. At the cutting edge, we investigate nonrelativistic bound
states in intricate environments, like the newly discovered exotics X, Y,
Z  above the strong decay threshold and the behavior in out-of-equilibrium
scenarios, such as quarkonium suppression in a Quark Gluon Plasma or dark
matter interactions in the early universe.

Our ability to achieve precision calculations and control strongly
interacting systems is closely linked to bridging perturbative methods
with nonperturbative tools, notably numerical lattice gauge theories.

The ultracold neutron (UCN) source at the Paul Scherrer Institut (PSI) is
being successfully operated since 2011 and has provided UCN for example
to the nEDM experiment, which has placed the tightest constraints to
date on the neutron's electric dipole moment in 2020. Currently the
successor experiment n2EDM is being commissioned at the same position.
At the second beam port, the neutron lifetime experiment τSPECT,
developed at Johannes Gutenberg University Mainz, is currently being set up for data taking. τSPECT is the first neutron lifetime experiment using spin-flip loading and 3-dimensional magnetic storage of neutrons.

In this seminar, I will talk about electroweak symmetric balls, which are macroscopic objects that exhibit restored electroweak symmetry within. These objects can arise in models featuring a dark sector containing monopoles or non-topological solitons that interact with the Standard Model through a Higgs portal. In the early universe, they could have emerged via a phase transition or preheating mechanism, accounting for all dark matter. Because of their electroweak symmetric cores, these objects have a large geometric cross-section relative to a nucleus, which generates a multi-hit signature in large-volume detectors. Furthermore, they can capture a nucleus through radiative means, releasing up to a GeV of energy for each interaction. This makes them excellent targets for large-volume neutrino detectors. The IceCube detector, in particular, provides a promising avenue for exploring the properties of these fascinating objects, with the potential to probe dark matter balls weighing up to one gram.

In recent years, new theories of particle physics have been discovered whose short-distance behaviour is controlled by an interacting (rather than a free) UV fixed point. The very existence of these asymptotically safe particle theories has opened up new directions to UV-complete the Standard Model of particle physics beyond the paradigm of asymptotic freedom. In this talk, I give a systematic overview of QCD-like theories with weakly and strongly coupled fixed points, with and w/o supersymmetry, and discuss key features. Concrete applications for BSM physics are also given. If time permits, I briefly outline how some of these ideas and insights are used to understand the quantisation of gravity.

Among the four known fundamental forces or interactions, gravitation and electromagnetism are close to daily life, while the strong and weak forces only reveal themselves at sub-atomic or smaller scales. The strong force, which is mediated by gluon exchange between quarks confines quarks into protons and neutrons (nucleons). The residual component of this strong force that induces the strong nuclear interactions between nucleons at the fermi scale (10^-15m). This so-called "nuclear force" is attractive at a longer distance (e.g. for nucleon separation greater than the proton radius) and binds nucleons together into nuclei), while the force is strongly repulsive at a much shorter distance which prevents the nucleus from collapsing. 
Nucleon interactions at short distances are not well-described in either QCD or the field theory. Experimentally, a series of electron-nucleon scattering measurements at Jefferson Lab (JLab) have determined about 20% of nucleons in heavy nuclei are moving fast (above the Fermi momentum) due to hard, short-distance interactions with another nucleons, forming so-called short-range correlated (SRC) pairs. Understanding those SRC pairs is necessary in providing a complete  description of nuclear structure. It also offers us a unique chance to probe the tensor and repulsive force at intermediate to short distances. In this talk, I will present recent results from the JLab Hall A tritium program which studied the momentum distribution, and spin/isospin structure of SRC pairs in the mirror nuclei tritium and helium-3. I will then discuss how those measurements help us better understand the short-distance part of strong nucleon-nucleon interactions, and their connections to future experiments.

The axion is one of the best motivated dark matter candidates, simultaneously solving the Strong CP problem as well as providing the dark matter of the universe. However, in comparison to WIMPs the axion was historically neglected by experimental efforts. This has been changing in the last five years, which a bevy of new experiment proposals and results. I outline several recent updates for new detection ideas, including plasma haloscopes and axion detection with phonon-polaritons.