Physicists gave OpenAI Codex and Anthropic Claude responsibility for much of an experimental particle-physics analysis, from processing archived detector data to generating figures and drafting the manuscript. The humans defined the measurement, approved methods, and reviewed the output. The resulting arXiv paper, Agentic AI - Physicist Collaboration in Experimental Particle Physics, reports the thrust distribution in electron-positron collisions at a center-of-mass energy of 91.2 GeV using data from CERN’s ALEPH experiment.

A benchmark with an answer key

Thrust compresses the shape of a collision event into a number between 0.5 and 1. For each event, the calculation finds the axis that maximizes the summed particle momenta projected along it. A value near 1 describes two narrow, back-to-back jets; a value near 0.5 describes a more spherical spray of particles. Physicists use thrust to study quantum chromodynamics, including gluon radiation and the strong coupling constant.

ALEPH recorded millions of Z-boson decays at CERN’s Large Electron-Positron Collider during the 1990s. At 91.2 GeV, the collider operated near the Z-boson resonance, where hadronic decays provided a large, well-studied event sample. Archived ALEPH data suit an agentic workflow test because historical measurements provide a reference against which researchers can detect biased selections, incorrect corrections, or faulty uncertainty estimates.

From event records to a corrected spectrum

The agents executed the main stages of a collider analysis while physicists reviewed intermediate results and methodological choices:

• Read ALEPH event records and classify reconstructed objects as charged particles, neutral hadrons, photons, electrons, or muons.