"To claim a discovery" means to assert ownership or credit for a new or significant finding or breakthrough that one has made, often by presenting evidence or providing proof of its existence. Full definition
The team is not claiming discovery of dark matter, because the result is not statistically significant. (newscientist.com)
They do this for all the possible decay modes, and only when they see a statistically significant excess can scientists claim a discovery. (press.cern)
It's not the first time physicists have claimed the discovery of element 113. (sciencemag.org)