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Elementary particle physics

Working at the forefront of particle physics, SLAC scientists use powerful particle accelerators to create and study nature’s fundamental building blocks and forces, build sensitive detectors to search for new particles and develop theories that explain and guide experiments. SLAC’s particle physicists want to understand our universe – from its smallest constituents to its largest structures.

SLAC researchers study Higgs boson particles.

The Higgs boson and beyond

SLAC builds and operates detector components for ATLAS, one of two experiments at CERN’s Large Hadron Collider that were involved in the discovery of the Higgs particle. We also develop sophisticated tools to analyze particle collisions and host a computing center for ATLAS data.

Higgs boson news

Research Project


ATLAS records head-on collisions of extremely high-energy protons, then searches through these collisions for signs of never-before-seen particles and interactions.

ATLAS records head-on collisions of extremely high-energy protons.

Symmetry Magazine stories on the ATLAS experiment

ATLAS experiment
The LZ detector will search for WIMPs.

Particles of dark light

Scientists know from the motions of galaxies that the universe contains about five times more dark matter than visible matter, but they don’t know what form it takes or what forces might affect it. One possibility is that dark, heavy versions of photons – particles of light – could be at play. SLAC researchers have developed theories of these photons and designed and built crucial parts of an experiment aimed at finding them.

Dark matter news

Research Project

Heavy Photon Search (HPS)

With help from SLAC scientists, HPS is searching for dark photons that could carry dark forces between dark matter particles.

Heavy photon search.

The Heavy Photon Search at Jefferson Lab is looking for a hypothetical particle from a hidden “dark sector.”

Heavy Photon Search.

Dark matter hunters around the world pursue three approaches to look for fingerprints of ghostly WIMPs: on the Earth’s surface, underground and in space.

Researchers around the world pursue three approaches to look for fingerprints of dark matter's ghostly components.
The EXO-200 underground detector.

Understanding neutrinos

Neutrinos are among the most mysterious particles, but they are difficult to study – they can pass through lead nearly 6 trillion miles thick without leaving a trace. SLAC researchers want to answer fundamental questions about neutrinos, including whether a new type of neutrino could be linked to dark matter and whether neutrinos explain why there is more matter than antimatter in the universe.

Neutrino news

Neutrinos have a small, finite mass, opening up the possibility that they are their own antiparticles, which may explain why their masses are so different from all other particles. EXO will search for a sign of this possibility, called neutrinoless beta decay.

The xenon vessel, ready to be inserted into the cryostat.

DUNE looks for signs of neutrino oscillation – one kind of neutrino turning into others. By measuring oscillation properties, the experiment may shed light on why there is more matter than antimatter in the universe.

Proto-DUNE SP detector using test beam.
SLAC theorist Lance Dixon writes out a new formula.

The theoretical foundation

Theory is the fundamental tool that explains what scientists observe in experiments and gives them a better idea of where to look for the next big discovery. SLAC theorists explore particle physics, particle astrophysics and cosmology, including searches for new phenomena, extra dimensions, collider physics, neutrino physics, dark matter and cosmic inflation.

Theoretical physics news

The theory group at SLAC studies the so-called strong interactions, extensions of the standard model, computer simulations of particle physics experiments and more.


A collection of stories featuring SLAC elementary particle theorists.

Symmetry Magazine.