Anthropic says Claude solved a nine-loop physics problem on its own

US AI company Anthropic says its model Claude ran for days with almost no human help and solved a long-standing high-energy physics problem: the nine-loop scattering amplitude. The result is for six-particle amplitudes in planar N=4 super Yang-Mills theory. The previous human record was eight loops. With just one prompt, Claude worked on its own for days, and one part of the answer has over 30 billion terms.

Lance Dixon, the professor who held the eight-loop record, verified the result. After two weeks of checking, he said the nine-loop answer is correct. He noted that Claude used methods his team had developed over years and wrote all the complex code by itself. The cost was only a few thousand dollars, with about $100 for pure Python computing.

Notably, a team from the Institute of Theoretical Physics at the Chinese Academy of Sciences, led by He Song, also published core skeleton data from two to nine loops on September 17, eight days before Anthropic's announcement. Dixon said GPT-6 helped the Chinese team compute some constraints, but humans still built the overall framework.