In an underground ring 27 kilometers in circumference, protons are accelerated to nearly the speed of light and smashed head-on. At the collision point, conditions briefly recreate those of the first trillionth of a second after the birth of the universe. The CMS detector (a multi-story machine of silicon, lead, and superconducting magnets) captures the debris of these collisions.
Among the debris, physicists search for traces of W and Z bosons — particles that carry the weak force, which makes the Sun shine and some nuclei decay. They measure them with precision down to fractions of a percent: how often they are produced, at what angles they fly apart, how quickly they decay. Such precision makes it possible to spot the slightest deviation from theory, if any exists.
The most sensitive test is the electroweak mixing angle. It shows how electricity and the weak force are intertwined. A deviation of one-thousandth of a radian would mean new physics: unknown particles or extra dimensions. So far, everything agrees with predictions, but the precision is such that even a weak signal would be noticed.
Proton collisions are a blunt instrument compared to clean electron beams, but they provide enormous statistics. Billions of events allow random fluctuations to be averaged out and a signal to be extracted that would otherwise drown in noise. Thus the collider becomes a microscope for the most fundamental laws of nature.
as written by the authors arXiv:2603.12961
Recent measurements of electroweak phenomena from the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider are summarized. The standard model of particle physics was tested through highly precise determinations of its key electroweak parameters and through measurements of electroweak processes in proton-proton collisions at unprecedented center-of-mass energies of up to $$13.6 \, \mathrm{TeV}$$. The performance of the CMS experiment establishes its key role in the study of electroweak physics, with many measurements performed either for the first time or with the best precision at a proton-proton collider, in some cases reaching or even surpassing the precision of legacy results from lepton colliders. Recent electroweak results from the CMS experiment include: measurements of the W and Z bosons production cross sections; high-precision measurements of the forward-backward asymmetry in Drell-Yan production and of the effective leptonic electroweak mixing angle; measurements of tau lepton properties and of multiboson production and vector boson scattering rates.
The proton collision energy at the Large Hadron Collider, 13.6 TeV, is equivalent to the energy of a flying mosquito, but compressed into a volume a million billion times smaller than a grain of sand.
In the series "Dark Matter," a collider is used to search for particles that explain the hidden mass of the universe, just like the real experiments at CMS.