Indications of a four-quark structure for the X(3872) and X(3876) particles from recent Belle and BABAR data.

ABSTRACT

Recent results by Belle and BABAR point to the existence of a second X particle decaying in D(0)D(0)pi(0), a few MeV above the X(3872). We identify the two X states with the neutral particles predicted by the four-quark model and show that production and decays are consistent with this assignment. We consider the yet-to-be-observed charged partners and give new hints on how to look for them.