We present a QCD analysis of the effective weak Hamiltonian at hadronic energy scales for strangeness-nonchanging (∆S = 0) hadronic processes. Performing a leading-order renormalization group analysis in QCD from the weak to the O(2 GeV) energy scale, we derive the pertinent effective Hamiltonian for hadronic parity violation, including the effects of both neutral and charged weak currents. We compute the complete renormalization group evolution of all isosectors and the evolution through heavy-flavor thresholds for the first time. We show that the additional four-quark operators that enter below the electroweak scale from QCD operator mixing effects form a closed set, and they result in a 12×12 anomalous dimension matrix. We use the resulting effective Hamiltonian to determine the parity-violating meson-nucleon coupling constants, h^1_π , h^{ 0,1,2}_ ρ , h^{0,1}_ ω , employing the factorization Ansatz and assessments of the pertinent quark charges of the nucleon in lattice QCD at the 2 GeV scale. On this basis, we connect to earlier calculations of low-energy, hadronic parity-violating observables in few-nucleon systems to make theoretical predictions that we compare with recent experimental results, for a global view of the relative importance of the various isosectors. 

Stars have the potential to be excellent dark matter detectors; dark matter could heat them up, destroy them by forming black holes, or modify heat transport. To predict when and how this might happen, we need to compute the scattering rate of dark matter inside stars. In this talk, I will describe how, for a wide range of dark matter models, this requires taking into account collective effects - that is, coherent scattering with many particles inside the star. These effects have been neglected in many previous treatments; I will show how they can enhance or suppress naive predictions for dark matter scattering rates by orders of magnitude. Calculations can be performed systematically by computing in-medium effective propagators, using the apparatus of thermal field theory.

Stars and planets can be ideal playgrounds to discover dark matter. In this talk, I will review a range of dark matter searches using celestial objects, including exoplanets, solar-system planets, and our Sun. I will also discuss a new framework to describe what happens when dark matter is captured inside these objects, and the implications for dark matter search strategies.

Heavy quarks and their bound states are ideal probes of the medium formed in heavy ion collisions.  The resulting hierarchy of scales of in-medium heavy quarkonium makes the combined system ideally suited for treatment using nonrelativistic effective field theories and the formalism of open quantum systems (OQS).  My talk will consist of three parts: in the first, I will present an introduction to nonrelativistic QCD (NRQCD), potential NRQCD (pNRQCD), and the OQS formalism; in the second, I will present the derivation of the master equation governing the evolution of in-medium heavy quarkonium; and in the third, I will discuss solutions of the master equation and present recent phenomenological results for the nuclear modification factor and the elliptic flow compared against experimental measurements.

Classical field theories of scalars that are invariant under a U(1) symmetry can have non-perturbative soliton solutions called Q-balls: spherical bound states that are the energy minimum for a fixed U(1) charge Q. The underlying non-linear differential equations cannot be solved analytically, but I will present analytical approximations that work remarkably well and allow us to understand both ground and excited Q-ball states with ease. The global U(1) symmetry can also be promoted to a gauge symmetry, leading to gauged Q-balls and Q-shells; once again we can find exceptionally good analytic approximations to describe these objects and their stability.

The QCD axion is one of the most compelling solutions of the strong CP problem. There are major current efforts into searching for ultralight axion dark matter, which is believed to be the only phenomenologically viable realization of the QCD axion. Visible axions with decay constants at or below the electroweak scale are believed to have been long excluded by laboratory searches. In this talk, I will revisit experimental constraints on QCD axions in the O(10 MeV) mass range and show that a specific variant of the QCD axion remains compatible with existing constraints. Specifically, the axion must (i) couple predominantly to the first generation of SM fermions; (ii) decay to e+e− with a short lifetime of less than 10^−13 s; and (iii) have suppressed isovector couplings, i.e., if it must be piophobic. Remarkably, these are precisely the properties required to explain recently observed anomalies in nuclear de-excitations of the Be-8 and He-4 nuclei, as well as the 2−3 sigma anomaly in the measurement of the neutral pion branching ratio to e+e-. I will discuss a variety of low-energy axion signatures, such as rare meson decays, nuclear de-excitations via axion emission, and axion production in e+e− annihilation and fixed target experiments.