Ab initio methods, for which the only input is the inter-nucleon interaction, play an important role in describing nuclei for which there is limited data, particulalry in regions of the nuclear chart far from stability. However, quantitative predictions are computationally limited by the explosion in scale as the number of nulceons increases. Approximate symmetries of the nucleus can be used to combat this explosion using symmetry adapted approaches. At the same time, these symmetries can be used to gain insight into simple patterns which arise in the spectrum. I will discuss the emergences of two such approximate symmetries, SU(3) and Sp(3,R), associated with nuclear deformations, rotations and giant resonnances and how these symmetries are employed in the ab initio symplectic no-core configuration iteraction framework.

Some of the most interesting questions in modern physics are those regarding the nature, origin, and interactions of the fundamental constituents of matter. The answers to such questions can make a huge difference in how we understand the universe. Investigating them often involves an exciting combination of applications from many different fields - nuclear physics, particle physics, astrophysics, and more - to design and implement detectors capable of detecting tiny signals that could provide hints of new physics. In this talk, we describe a few of the questions our lab is trying to answer and how we look for physics beyond the standard model.

Ab-initio methods provide a direct connection between nuclear physics and the underlying fundamental theory, permitting the use of nuclei as probes to study fundamental physics. In order to do this, we need to start from a nuclear model constructed from first-principles such in chiral effective field theory. Then reliable and accurate methods to solve the Schrödinger equation are needed.
In this seminar we will introduce the Hyperspherical Harmonic (HH) method as the approach we used to solve the Schrödinger equation. We will focus in particular on some recent improvements that permit to treat nuclei up to A = 6. We will then show some examples on how this method, together with chiral effective field theory, has been used to study time reversal violation and β-decay in light nuclei. Finally we will briefly discuss how the HH method could be extended to treat also scattering states, opening up new frontiers for the ab-initio calculations.

Background: Recent developments in effective field theory and many-body theory have pushed the limits of ab initio calculation to the 208Pb region with impressive precision [1]. This means that it becomes possible to obtain first-principles computation (with quantified uncertainties) of quantities which even reside in the heavy-mass region. The quantities include these relevant for astrophysics and searches for physics beyond the Standard Model. However, ab initio calculations for scattering and reactions are much more limited. Methods: F (Facilities, ab initio many-body method, such as in-medium similarity renormalization group, IMSRG) for R (Resonance and continuum), I (astrophysics), and B (Beyond the Standard Model) Results: I will discuss how to couple nuclear scattering states and decay channels into the IMSRG framework by using the complex-energy Berggren representation. The new IMSRG approach can describe properties of weakly-bound and unbound open quantum systems, such as limits of atomic nuclei, resonance, and halo. I will also report ongoing efforts to extend IMSRG to unify nuclear structure and reactions, especially for proton or neutron scattering and radiative capture reactions. In the second part of this talk, I will introduce some unreported strong correlations between electric dipole polarizability, binding energy, and symmetry energy parameters unlocked by large scale (range from 40Ca to 132Sn) ab initio calculations. Based on these correlations, I will show robust constraints on the equation of state of nuclear matter. Last but not least, I will present the recent ab initio calculation of nuclear responses for dark matter direct detection. Conclusion: FRIB physics needs theoretical 'FRIB'. [1] Ab initio predictions link the neutron skin of 208Pb to nuclear forces. B.S. Hu, et al. In preparation (2021).

The purpose is to maintain ISNET's mission of bringing the nuclear physics and statistical sciences communities together to report on the latest progress and to provide a vehicle for educating and enlightening the nuclear physics community in regards to the application of statistical methodologies that enable nuclear physics to reach more quantitatively rigorous scientific conclusions. The dates for the meeting are December 14th - 16th 2021, and will start Tuesday morning and end Thursday afternoon. For 2021 ISNET 8 will be an "a hybrid " meeting. All talks will be delivered on-site, but sessions will also broadcasted via ZOOM for remote participants. https://indico.frib.msu.edu/event/47/

Committee: Hironori Iwasaki (Chairperson), Kaitlin Cook, Sean Liddick, Dean Lee, Stuart Tessmer

Despite considerable progresses during the last decades, the origin of trans-iron elements is not yet fully understood. These elements are thought to be produced by a variety of nucleosynthetic processes, the main ones being the so called slow (s) and rapid (r) neutron capture processes. An intermediate neutron capture process (i-process) is also thought to occur at neutron densities intermediate between the s- and r-processes. This is supported by the observation of metal-poor stars whose chemical compositions is between the s- and r-processes (the so called r/s-stars). An important challenge is to associate each nucleosynthetic process with its astrophysical source(s). In the first part of the presentation, I will discuss the synthesis of trans-iron elements in low metallicity massive stellar models. In particular, I will show how stellar rotation is expected to alter the synthesis of heavy elements both during the life and explosion of the massive star, and ultimately lead to a material with a chemical composition intermediate between the standard s- and r-processes. In the second part of this presentation, I will focus on the development of the i-process in low-metallicity AGB stars models. In both parts, I will highlight the chemical fingerprint of the discussed nucleosynthetic processes, identify key reaction rates and compare model predictions with observed r/s-stars.

Visualization of structural changes of materials with atomic spatial (Angstrom) and temporal resolutions (femtosecond) is of crucial importance to the understanding of the relation between structure and functionality, and the ultimate goal of controlling energy and matter [1]. In the past decades, ultrafast electron diffraction/microscopy (UED/UEM) has been rapidly developing, aiming to provide the relevant length and time scales for ultrafast science [2-3]. With the advent of high accelerating gradient radiofrequency photoinjector, high brightness electron beam at mega-electron-volt (MeV) energy has become accessible for UED to reach ~1 Å spatial resolution and ~100 femtosecond temporal resolution. In 2014, SLAC National Accelerator Laboratory launched a UED/UEM initiative, aiming to provide the world's leading ultrafast electron scattering instrument using MeV electron beams. A prototypical MeV UED beamline was built and has been evolving over the years [4-6] for the goal that has long been envisioned -- making space-and-time resolved molecular movies. A great number of successful ultrafast scientific results have been achieved at SLAC MeV UED in the regions of condense matter physics, warm-dense matter physics, as well as chemical science [7-9]. Since 2019, SLAC MeV UED has become an official user facility as part of Linac Coherent Light Source to serve the ultrafast science community [10]. In this talk, the experimental set up of SLAC MeV UED and selected ultrafast scientific results will be presented. Research and development efforts to further expand the capabilities of SLAC MeV UED will also be discussed. [1] "Directing matter and energy: Five challenges for science and the imagination", A Report from the Basic Energy Sciences Advisory Committee, 2007, (http://science.energy.gov/~/media/bes/pdf/reports/files/gc_rpt.pdf). [2] R. J. D. Miller, Science 343, 1108 (2014). [3] Ahmed H. Zewail, Science 328, 187 (2010). [4] S. P. Weathersby, et al., Review of Scientific Instruments 86, 073702 (2015). [5] X. Shen, et al., Ultramicroscopy 2018, 184, 172-176. [6] X. Shen, et al., Struct. Dyn. 6, 054305 (2019). [7] E. J. Sie, et al., Nature 565, 61 (2019). [8] M. Z. Mo, et al., Science 360, 1451 (2018). [9] J. Yang, et al., Science 361, 64 (2018). [10] SLAC MeV UED user facility webpage (https://lcls.slac.stanford.edu/instruments/mev-ued)