Claude computes a nine-loop particle-physics amplitude, and a rival group was nearly there first

Anthropic says Claude computed the six-particle scattering amplitude in planar N=4 super-Yang-Mills at nine loops, one order beyond the previous eight-loop record held by SLAC's Lance Dixon and collaborators.

Anthropic physicists Liam Fitzpatrick and Siddharth Mishra-Sharma gave Claude a one-line prompt. It ran largely unsupervised for days using the established bootstrap method, at a total cost of a few thousand dollars. Dixon validated the result independently. The physicist Matt von Hippel, who issued the original public challenge in August, wrote the guest post.

The footnote

• Claude used known methods, the ones Dixon and his colleagues built, and pushed them one loop further. It did not find new physics.
• A group led by Song He at the Chinese Academy of Sciences, working with GPT-6, had already obtained most of the same result. Their dataset is dated 17 September.

Why it matters

This is one of the most concrete cases yet of a language model completing a frontier research calculation end to end on an academic budget. But the accurate headline is "ai grinds", not "ai discovers": known methods, run faster and cheaper than a person could. That may be just as impressive. It is a different claim, and most coverage has flattened it into "ai breaks physics record".