“X(3872)” the mystery meson
A new particle has been confirmed at Fermilab. This new particle is dubbed the mystery meson for it configuration does not fit any known particle scheme. This meson consists of 2 quarks and 2 antiquarks.
Mesons are particles that contain a quark and an antiquark that are held together by the strong nuclear force. Since there are six different “flavours” of quark - up, down, strange, charm, bottom and top - it is possible to form a large number of different mesons.
The Belle team measured the decay of B-mesons - mesons that contain a bottom quark - produced in electron-positron collisions at the KEK B-factory in Japan. The team plotted the number of candidate events for B mesons against mass and observed a significant spike in the distribution at 0.775 GeV. This corresponds to a mass of nearly 3872 MeV. The particle decayed almost immediately into other, longer lived particles.
The KEK team says that the mass of this new meson is higher than theoretical predictions. Moreover, the way in which it decays also differs from theory. One possibility is that current models of the strong force need to be modified. Alternatively it could be that X(3872) is the first example of a “molecular state” meson that contains two quarks and two antiquarks.
As of yet, I’m not sure what the significance of this finding is, but that isn’t stopping the physicists. They also say that there are other particles that have been recently discovered; another four-quark particle known as the Ds(2317) and a five-quark particle known as the pentaquark.
Source: Physics Web
October 9th, 2004 at 1:01 pm
Transient molecule-like “associations” of quarks, my own idiosyncratic analyses show, are universal. Available detectors do not have the time resolution to show the one I consider type-definitive: In the decay of the free neutron the associative pentaquark dduuu-minus fleetingly forms while the u-minus and one of the two d quarks are conglomerating to form the W-minus, that being the particle that will be characteristically emitted.
I am tickled to be able to suggest that the pentaquark I propose here may exist for only a single order of magnitude (2-to-10) of quantal time units.