Observation of the $B^0\to {\rho }^0{\rho }^0$ decay from an amplitude analysis of $B^0\to ({\pi }^{+}{\pi }^{-})({\pi }^{+}{\pi }^{-})$ decays

LHCb collaboration, R. Aaij, B. Adeva +699

Proton-proton collision data recorded in 2011 and 2012 by the \lhcb experiment, co\-rres\-pon\-ding to an integrated luminosity of 3.0\invfb, are a\-na\-lysed to search for the cha…