Interpretation of Neutral Charm Mesons near Threshold as Unparticles

The existence of the X(3872) resonance extremely close to the D-*0(D) over bar (0) threshold implies that neutral charm mesons have an approximate nonrelativistic conformal symmetry. Systems consisting of these mesons with small kinetic energies produced in a short-distance reaction are unparticles in the sense that they can be created by operators with definite scaling dimensions in a nonrelativistic conformal field theory. There is a scaling region in which their energy distribution has power-law behavior with an exponent determined by the scaling dimension of the operator. The unparticle associated with two neutral charm mesons produces a peak in the recoil momentum spectrum of K-+/- in inclusive decays of B-+/- that has been observed. The scaling dimensions of the unparticles associated with three neutral charm mesons are calculated. They can be determined experimentally by measuring the invariant mass distributions for XD0 or XD*0 in inclusive prompt production at the Large Hadron Collider.

Automated summary

The discovery of the X(3872) resonance being extremely close to the D-*0(D) over bar (0) threshold suggests the presence of approximate nonrelativistic conformal symmetry in neutral charm mesons. This study shows that systems consisting of these mesons with low kinetic energies produced in short-distance reactions can be considered as unparticles, created by operators with definite scaling dimensions in a nonrelativistic conformal field theory.