Skip to main content Topics Higgs boson Neutrinos Dark matter Dark energy New physics Applications Full archive Follow Search A joint Fermilab SLAC publication LHC physicists discover five-quark particle 07 14 15 By Sarah Charley Pentaquarks are no longer just a . theory Artwork by CERN Protons and neutrons , which together with electrons form atoms , are made up of even smaller particles called quarks . Protons and neutrons contain three quarks . each Scientists at the LHCb experiment at the Large Hadron Collider just discovered two particles made up of not three , not four , but five quarks the first observed pentaquarks . Scientists have been searching for this class of particles for about 50 . years The pentaquark is not just any new particle , rdquo says LHCb spokesperson Guy