Scientists of the Collider Detector at Fermilab (CDF) experiment at the Department of Energy’s Fermi National Accelerator Laboratory announced that they have found evidence of an unexpected particle whose curious characteristics may reveal new ways that quarks can combine to form matter.
The CDF physicists have called the particle Y(4140), reflecting its measured mass of 4140 Mega-electron volts. Physicists did not predict its existence because Y(4140) appears to flout nature’s known rules for fitting quarks and antiquarks together.
“It must be trying to tell us something,” said CDF cospokesperson Jacobo Konigsberg of the University of Florida. “So far, we’re not sure what that is, but rest assured we’ll keep on listening.”
Matter as we know it comprises building blocks called quarks. Quarks fit together in various well-established ways to build other particles: mesons, made of a quark-antiquark pair, and baryons, made of three quarks. So far, it’s not clear exactly what Y(4140) is made of.
The Y(4140) particle decays into a pair of other particles, the J/psi and the phi, suggesting to physicists that it might be a composition of charm and anticharm quarks. However, the characteristics of this decay do not fit the conventional expectations for such a make-up. Other possible interpretations beyond a simple quark-antiquark structure are hybrid particles that also contain gluons, or even four-quark combinations.