From Quarks To Chemistry

Protons, neutrons, and hundreds of other much less stable hadrons  (i.e. systems of quarks and/or gluons bound by the strong force) are understood quite well with the Standard Model of Particle Physics, although there are challenges in understanding scalar mesons, axial vector mesons, and hadrons with four or more quarks, as well as in distinguishing true hadrons with four or more quarks from "hadron molecules", and predicting the full spectrum of hadrons from first principles.

Protons and neutrons in atomic nuclei are not bound together primarily by the strong force itself. Instead, the nuclear binding force between protons and neutrons in an atomic nucleus is the sum of the forces arising from the exchange of several kinds of light mesons (primarily pions but also other light mesons including kaons).

We are not quite there in terms of using Standard Model physics to explain the physics and chemistry of atomic nuclei, although we are getting closer to achieving this vertical integration of subatomic and atomic scale phenomena, and we making great progress on this front. Part of the hold up is the challenge of explaining "parton distribution functions" (PDFs), a property of hadrons that, in principle, can be worked out from first principles with Standard Model physics. But until the past few years, PDFs have actually been determined almost entirely from brute force raw data collection and organization from particle accelerator data.

We also mostly understand the way electrons interact with atomic nuclei, which is almost entirely an electromagnetic quantum electrodynamics (QED) phenomena.

The next layer above understanding atoms, is chemistry, which pertains mostly to how atoms interact with each other, much of which ultimately flow from the physics of atomic nuceli.

We extend the QCD Parton Model analysis by employing a factorized nuclear structure model that explicitly accounts for both individual nucleons and correlated nucleon pairs. This novel framework establishes a paradigm that directly links the nuclear physics description of matter (in terms of protons and neutrons) to the particle physics schema (in terms of quarks and gluons). 

Our analysis of high-energy data from lepton Deep-Inelastic Scattering, Drell-Yan, and W/Z production simultaneously extracts the universal effective distribution of quarks and gluons inside correlated nucleon pairs, and their nucleus-specific fractions. 

The successful extraction of these universal distributions marks a significant advance in our understanding of nuclear structure, as it directly connects nucleon-level and parton-level quantities.

Fredrick Olness, "Bridging the Gap: Connecting Atomic Nuclei to Their Quantum Foundations" arXiv:2511.15659 (November 19) ("Talk presented at the 32nd International Workshop on Deep Inelastic Scattering and Related Subjects (DIS 2025), Capetown, South Africa, 24-28 March 2025. To appear in the proceedings").