Is this particle really the Higgs Boson? Does it swim and quack like a duck?

While decays of this kind had been observed for the new particle by July 4, the rates at which they occur were still uncertain. It was not even known if the newly discovered particle has the right quantum numbers-that is, whether it has the spin and parity required of a Higgs boson.

In other words, the July 4 particle looks like a duck, but we need to make sure it swims like a duck and quacks like a duck.

All the results from ATLAS and CMS (as well as from the Tevatron Collider at Fermilab) since 4 July 2012 have shown remarkable consistency with the expected branching ratios to the five decay modes discussed above, and consistency with the expected spin (zero) and parity (positive); these are the main quantum numbers.

These properties are essential to determine if the new particle really is the Higgs boson predicted by the Standard Model or some other unexpected particle. So far, all available evidence points to the new particle being the Standard Model Higgs boson.

Some physicists actually find this disappointing! If the new particle is the Standard Model Higgs boson, and the theory is confirmed, then the Standard Model will essentially be complete. The only thing left to do will be to make increasingly accurate measurements of what's already been confirmed.

But if the new particle turns out to be something not predicted by the Standard Model, then that opens the door to lots of new theories and ideas to be tested! Unexpected results always require new explanations, and help push theoretical physics forward.