Higgs boson
The hypothesised Higgs mechanism made several accurate predictions. One crucial prediction was that a matching particle called the "Higgs boson" should also exist. Proving the existence of the Higgs boson could prove whether the Higgs field existed, and therefore finally prove whether the Standard Model's explanation was correct. Therefore, there was an extensive search for the Higgs boson, as a way to prove the Higgs field itself existed.