The ATLAS experiment, performed at the Large Hadron Collider at CERN, confirmed that three particles – top quark, top antiquark and W boson – are recorded more frequently in proton-proton collisions in the accelerator than the Standard Model predicts. This was reported in the press release of the SLAC National Accelerator Laboratory.

The triple particle generating event, called ttW, is extremely rare and occurs every 50,000 collisions. All particles are short-lived and decay almost instantly, so they are registered by their decay products – electrons and muons. Currently, the Large Hadron Collider is the only accelerator capable of generating ttW.

The ATLAS group first observed the ttW process in 2015 using data from the collider’s 1st Operation session from 2010 to 2012. The following measurements were made on data from the Run 2 session (2015-2018), which led physicists to conclude that the decay of protons into triplet particles does not exactly correspond to the currently most widely used Standard Model. It precisely describes the behavior of known subatomic particles and exceeds the predicted value by 20 percent.

According to scientists, the anomaly can have several explanations. First, the model itself may have some of the details necessary to accurately predict the ttW. Second, the anomaly may be an indication of the existence of New Physics outside of the Standard Model.