Scientists have discovered two new particles in the baryon family. The particles, discovered by LHCb experiment researchers, are known as Xi_b’- and Xi_b*-. The quark model had previously predicted that the particles exist, although they had never been seen before now.

The collaboration for the LHCb experiment at CERN’s Large Hadron Collider announced this new discovery on November 19, 2014. The collaboration has submitted a paper reporting their finding to Physical Review Letters.

The CMS experiment at CERN discovered a related particle, the Xi_b*0, in 2012.

The newly discovered particles are baryons comprised of three quarks bound together by a strong force. However, the three types of quarks are different. Each of the new X_ib particles contain one beauty (b), one strange (s), and one down (d) quark.

The heavier b quarks are six times larger than the proton. The mass of the particles depends on the way they are configured.

Matthew Charles, from the CNRS’s LPNHE laboratory at Paris VI University, said in a statement, “Nature was kind and gave us two particles for the price of one.” He continued, “The Xi_b’- is very close in mass to the sum of its decay products: if it had been just a little lighter, we wouldn’t have seen it at all using the decay signature that we were looking for.”

According to The Particle Adventure, baryons are any hadron that consists of the three quarks.

Steven Blusk, from New York’s Syracuse University, concluded, “This is a very exciting result. Thanks to LHCb’s excellent hadron identification, which is unique among the LHC experiments, we were able to separate a very clean and strong signal from the background.”