For almost fifty years, we have also implicitly expected that the Standard Model also provides the underlying description of nuclear physics but have not had the the ability to make the necessary quantitative connections because of the intrinsically strongly-coupled nature of QCD. Over the last decade, I have been at the forefront of ground-breaking developments that are finally enabling these links to be made in a rigorous way. Using the analytical and numerical techniques of lattice QCD, my collaborators in the NPLQCD collaboration and I have laid the foundations of a fundamentally new approach to nuclear physics firmly rooted in the Standard Model. We have performed the first QCD calculation of a bound nucleus, the first calculations of the QCD properties of light nuclei, and the first QCD calculations of a nuclear reaction. This work is answering fundamental questions about the nature of strong interactions, providing critical information about hadrons and nuclei for upcoming experiments in particle and nuclear physics, and calculating quantities needed to understand astrophysical phenomena such as supernovae that cannot be measured in terrestrial experiments. To do this, we have significantly extended the scope and power of the lattice QCD method and developed a range of new techniques that allow us to tackle the many-body problems that define nuclear physics. 

A central aspect of nuclear physics is the complexity that nuclei exhibit, but this complexity is also one of the reasons that QCD calculations are so challenging. The QCD study of many- hadron systems was started by my innovative work on multi-pion systems which demonstrated that even though the calculations that are required grow factorially with the number of hadrons, n, involved, they can be computed efficiently by rethinking the way in which they are performed. My collaborators and I developed a contraction algorithm for these systems that is linear in n and used it to look at n ≤ 72 pion systems in order to explore the properties of matter at finite isospin density including the formation of a pionic Bose-Einstein condensate. My subsequent work on even more sophisticated contraction algorithms, as well as on statistical noise reduction in QCD calculations set the stage for attacking the still-more-challenging problem of nuclei from QCD and for the large scale numerical simulations that address the emergent structures of nuclei in QCD. My collaborators and I provided the first compelling QCD evidence for a multi-baryon bound state, albeit at unphysically heavy quark masses for computational expediency. In a follow up set of calculations, we performed a comprehensive analysis of light nuclei and hypernuclei up to atomic number A = 4, as well as of the binding of charmonium to nuclei.

In order to constrain the form of the nuclear equation of state that governs the dynamics of supernovae and the structure of the resultant neutron stars, my collaborators and I have used lattice QCD to calculate the nucleon-nucleon (NN) and hyperon-nucleon (YN) scattering phase shifts. NN phase shifts are well known from experiment and serve to verify the calculational tools we employ; on the other hand, YN interactions are extremely difficult to measure experimentally but are expected to be important in dense astrophysical environments. Using similar techniques, I will also study three-neutron forces which also become relevant at neutron star densities, far above those accessible in terrestrial experiments. With Standard Model calculations of these interactions, as well as new experimental probes of some aspects at the new Facility for Rare Isotope Beams, our confidence in predictions for these extreme environments is set to dramatically increase.

Having developed rudimentary QCD control of simple nuclei, we have turned to calculating their properties and interactions, as there is great potential for impact on phenomenology through understanding nuclear matrix elements. Since 2014, my collaborators and I have demonstrated that such calculations are feasible. We combined external field techniques (previously developed to study the structure of single hadrons) with our new multi-nucleon techniques, resulting in the first QCD calculations of the magnetic moments and polarizabilities of nuclei up to A = 4. These calculations form a prototype for determination of other properties of nuclei such as weak interaction matrix elements that are important for neutrino oscillation studies at the upcoming long-baseline neutrino experiments, as well as matrix elements that are relevant in dark matter direct detection experiments. Performing these calculations at the required precision represents an exciting challenge for the field. Most recently, we have begun to explore QCD calculations of nuclear reactions such as the thermal neutron capture process, np → dγ, the critical first step in primordial nucleosynthesis.