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Physicists on three international teams have recently spotted what's most likely a long-sought subatomic particle known as a pentaquark. It contains five components—four quarks and one antiquark—which are among the most fundamental bits of matter yet known. No subatomic particle detected previously contains more than three of those building blocks. "After 30 years of failing to find any convincing evidence for something that ought to be there, this recent news is certainly met with excitement," says nuclear physicist Andrew M. Sandorfi of Brookhaven National Laboratory in Upton, N.Y. Although unusually complex, the newfound particle fits within the prevailing theoretical framework...

All tetraquarks and pentaquarks that have been discovered so far contain two charm quarks, which are relatively heavy, and two or three light quarks – up, down or strange. This particular configuration is indeed the easiest to discover in experiments. But the latest tetraquark discovered by LHCb, which has been dubbed X(6900), is composed of four charm quarks. Produced in high-energy proton collisions at the Large Hadron Collider, the new tetraquark was observed via its decay into pairs of well-known particles called J/psi mesons, each made of a charm quark and a charm antiquark. This makes it particularly interesting as...

The newly-discovered particles, named Σb(6097)+ and Σb(6097)-, are predicted by the quark model, and belong to the same family of particles as the protons that the Large Hadron Collider (LHC) accelerates and collides: baryons, which are made up of three quarks. But the type of quarks they contain are different: whereas protons contain two up quarks and one down quark, the new particles are bottom baryons composed of one bottom quark and two up quarks or one bottom quark and two down quarks respectively.The LHCb researchers found these particles using the classic particle-hunting technique of looking for an excess of...

An exotic particle made up of five quarks has been discovered a decade after experiments seemed to rule out its existence. The short-lived ‘pentaquark’ was spotted by researchers analysing data on the decay of unstable particles in the LHCb experiment at the Large Hadron Collider (LHC) at CERN, Europe’s particle-physics laboratory near Geneva. The finding, says LHCb spokesperson Guy Wilkinson, opens a new era in physicists’ understanding of the strong nuclear force that holds atomic nuclei together. “The pentaquark is not just any new particle — it represents a way to aggregate quarks, namely the fundamental constituents of ordinary protons...

Ten days after the three-year anniversary of CERN’s discovery of the Higgs boson, researchers on the LHCb experiment at CERN have announced that another discovery has been made: They have found a new exotic class of particles. The team has submitted their findings to the journal Physical Review Letters for reviewal. These particles are called “pentaquarks,” and they offer some interesting insights regarding the nature of, well, nature. Typically, we find that composite particles consist of three quarks. The proton, for example, is composed of three valence quarks: Two up quarks and a down quark. But in 1964, American physicist...

Because perturbation theory doesn’t work, it is very hard to predict the consequences of the strong force. One thing we do know is that the binding energy of the strong force which holds the quarks together inside them is responsible for almost all of the mass of protons and neutrons, and hence almost all of the mass of you. Calculations on supercomputers (such as the DiRAC facility in the UK) use “lattice” methods to make calculations when perturbation theory doesn’t work. These involve approximating the space-time continuum by a lattice of discrete points and events; they are now able to...