LUX-ZEPLIN (LZ) is a direct detection dark matter experiment currently being operated at the Sanford Underground Research Facility (SURF) in Lead, South Dakota. The experiment utilizes 7 tonnes of liquid xenon in a dual phase time projection chamber to look for dark matter in the form of Weakly Interacting Massive Particles (WIMPs), as well as a broad range of other novel physics signals. LZ has recently released its first WIMP search results with an exposure of 60 live days using a fiducial mass of 5.5 tonnes. These results set new limits on spin-independent WIMP-nucleon cross-sections for WIMP masses above 9 GeV/c^2. This talk will give an overview of the LZ detector, a description of the first results, and a brief look at the science program that is now accessible with the LZ experiment.

Abstract: Rapid advancement in neutron-star observations allows unprecedented empirical access to cold, ultra-dense QCD matter, complementing collider experiments. The combination of these observations with theoretical calculations reveals previously inaccessible features of the equation of state and the phase diagram of QCD. In this talk, I demonstrate how perturbative-QCD calculations at asymptotically high densities robustly constrain the equation of state at neutron-star densities using a new method solely based on causality and stability. I confront these calculations with neutron-star observations in a Gaussian-process-based Bayesian framework and demonstrate that the perturbative-QCD calculations offer significant and nontrivial information, going beyond that which is obtainable from current observations. The main effect of the QCD input is to soften the equation of state at high densities, supporting the hypothesis that most massive neutron stars have quark matter cores.

Abstract: Axions are hypothetical particles that may explain the observed dark matter (DM) density and the non-observation of a neutron electric dipole moment. An increasing number of axion laboratory searches are underway worldwide, but these efforts are made difficult by the fact that the axion mass is largely unconstrained. If the axion is generated after inflation there is a unique mass that gives rise to the observed DM abundance; due to nonlinearities and topological defects known as axion strings, computing this mass accurately has been a challenge for four decades. Recent works, making use of large static lattice simulations, have led to largely disparate predictions for the axion mass, spanning the range from 25 microelectronvolts to over 500 microelectronvolts. In this talk, I will show that adaptive mesh refinement (AMR) simulations are better suited for axion cosmology than the previously-used static lattice simulations. Using dedicated AMR simulations we obtain an over three orders of magnitude leap in dynamic range and provide evidence that axion strings radiate their energy with a scale-invariant spectrum, to within ∼5% precision, leading to a mass prediction in the range (40,180) microelectronvolts. I will also comment on future development.

Abstract: Understanding the internal structure and dynamics of protons and neutrons, the complex many-body systems consisting of strongly-interacting quarks and gluons is at the core of exploring the visible matter universe. Gluons, which serve as mediator bosons of the strong interaction, play a key role in the nucleon’s mass and spin structures. In contrast, understanding of the gluon distributions and their role in hadron structures remains one of the most challenging but fundamental issues in nuclear and particle physics. In this talk, I will present lattice QCD calculations of matrix elements of bilocal operators composed of two gluon fields that can be used to determine the unpolarized and polarized gluon distributions. In particular, I will focus on the first lattice QCD determination of the gluon helicity parton distribution function with numerical evidence toward disfavoring negative gluon polarization in the nucleon.

Abstract: Next generation neutrino oscillation experiments are poised to provide answers to key questions about the nature of the neutrino. The axial form factor is a vital ingredient in the nucleon amplitudes used to predict quasielastic scattering, a primary signal measurement process for flagship neutrino oscillation experiments. The uncertainty on this form factor is vastly underestimated by the typical dipole parameterization and a model independent determination is not well constrained by elementary target data. To fulfill this experimental need, Lattice QCD can be used to compute, from first principles, the interaction of a nucleon with a weak current in the absence of a nuclear medium. Results from LQCD calculations will significantly improve constraints on the uncertainty of nucleon amplitudes and allow for a theoretically robust, systematically improvable error budget. Recent calculations of the nucleon axial vector coupling have demonstrated that sub-percent precision is within reach of current generation calculations. These LQCD results will permit factorization of uncertainties originating from nucleon and nuclear sources in order to better isolate the source of discrepancies with experimental data. In this talk, I will summarize the current state of Lattice QCD calculations of the nucleon quasielastic axial form factor and the implications of those calculations for long baseline neutrino oscillation experiments. I will show some preliminary results for LQCD calculations of the axial form factor and outline the path toward achieving a result with a complete error budget.

Abstract: Mu2e will operate with an unprecedentedly high intensity muon beam. During planned calibration runs (with \mu^+ rather than \mu^-) the experiment will collect on the order of 10^12 stopped muons. I will discuss a new proposal to search for BSM particles with masses below the muon and pion mass which result in a monoenergetic positron that can be observed in the Mu2e tracker. 

Abstract: The Deep Underground Neutrino Experiment (DUNE) will be the leading next-generation particle project in the US.  It aims to measure CP violation in the neutrino sector and determine the mass ordering of neutrinos.  These measurements are straightforward conceptually but challenging practically.  One outstanding issue is the modeling of GeV neutrino-nucleus interaction.  With a lack of a proper theoretical framework, it is not only difficult to simulate neutrino events in the detector accurately but also difficult to assess its impact on the physics measurements.  I will discuss our attempts at understanding how cross-section uncertainties impact oscillation measurements and new physics searches.

The strong suppression of bottomonia in ultrarelativistic heavy-ion collisions is a smoking gun for the production of a deconfined quark-gluon plasma (QGP).  In this talk, I will discuss recent work that aims to provide a more comprehensive and systematic understanding of bottomonium dynamics in the QGP.  The new paradigm is based on an open quantum system approach applied in the framework of the potential non-relativistic QCD EFT (pNRQCD), which has recently been extended to next-to-leading order in the binding energy over temperature.  I demonstrate that the computation of bottomonium suppression can be reduced to solving a Lindblad-type equation for the evolution of the b-bbar reduced density matrix including both singlet and octet states and transitions between them.  To solve the resulting Lindblad equation, we make use of a quantum trajectories algorithm which can be deployed in a massively parallel manner.  Our computation depends on two fundamental transport coefficients that have been evaluated independently using lattice QCD.  Comparisons with experimental data for bottomonium suppression and elliptic flow show very good agreement between theory and experiment.

Understanding the physics that governs the valence region of the nucleon is one of the central goals of hadronic physics. The valence region, which is ‘free’ from sea effects, stands as a challenging yet clean testing ground for various theoretical models that attempt to explain physics that operates this regime. Data from various complementary world wide efforts have recently provided tight constraints on PDFs in previously unmeasured regions at a wide range of Bjorken-x and Q2 for quarks, and anti-quarks.

Recently, three Jefferson Lab experiments, MARATHON (Hall A using 3H and 3He targets), BoNUS12 (Hall B using H and D targets), and F2d/F2p (Hall C using H and D targets) finished data taking in which they measured unpo- larized DIS cross sections. MARATHON and BONUS12 used novel techniques in minimizing nuclear effects in extracting the PDFs and their data will help constrain d(x)/u(x) ratio in the high-x region. Also, a planned experiment that proposes to use parity violation (PVDIS on the proton) using the proposed SoLID spectrometer will independently constrain the d(x)/u(x) ratio at high-x without contamination from nuclear corrections.

Recently, the SeaQuest experiment at Fermilab and RHIC at BNL used Drell-Yan dilepton production and W+/W− ratios to constrain the d(x)/u(x) ratio in the intermediate and ‘high-x’ region for sea quarks. Absolute Drell-Yan cross section data taken on a deuterium target at SeaQuest could also be used to constrain the d(x) + u(x) in the high-x region.

For the spin sector, An1 and dn2 experiments (Hall C using 3He target and a polarized e− beam) at Jefferson Lab successfully finished data taking. These experiments along with measurements on the proton from CLAS12 and SoLID will provide data on spin structure functions g1 and g2 for both, the proton and neutron, which will be used for flavor decomposition of u and d helicity distributions in the valence region. Overview of the experimental efforts and recent results will be presented in this talk.

Semi-inclusive deep-inelastic scattering (SIDIS) is an essential tool to probe the quark-gluon structure of the proton and thus for our understanding of non-perturbative QCD dynamics. The CLAS12 experiment has been taking physics data at the upgraded Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory since 2018. It takes advantage of the world record luminosities provided by CEBAF to perform an ambitious program of 3D imaging of the proton in momentum and position space. This talk will present the first results from the SIDIS program. I will focus on the first observation of beam-spin asymmetries in di-pion production in SIDIS. From the measured di-pion correlations a first extraction of the collinear twist-3 PDF e(x), which is sensitive to quark-gluon correlations in the proton, can be performed. Furthermore spin-orbit correlations in the hadronization of longitudinal polarized quarks into pions can be studied for the first time.