How Strong Is the Strong Force?

Physicists have determined the strong coupling constant (αs), which describes the force between quarks and gluons, to a precision of five parts per mille using lattice QCD calculations—a significant improvement over the previous one-in-a-hundred precision. This breakthrough addresses a critical theoretical bottleneck for collider physics, as current measurements at the LHC are now precise enough that uncertainty in the strong coupling limits the accuracy of predictions for new physics discoveries. The new value was calculated using low-energy input rather than fitting to collider data, allowing it to be used independently in future high-precision experiments like the High-Luminosity LHC.