LHCb investigates the properties of one of physics' most puzzling particles

χc1(3872) is an intriguing particle. It was first discovered over 20 years ago in B+ meson decays by the BELLE collaboration, KEK, Japan. Since then, the LHCb collaboration reported it in 2010 and has measured some of its properties. But here's the catch—physicists still don't know what it is actually made up of.