Search for doubly-heavy dibaryons in a quark model
  We study the stability of hexaquark systems containing two heavy quarks and four light quarks within a simple quark model. No bound or metastable state is found. The reason stems on a delicate interplay between chromoelectric and chromomagnetic effects. Our calculation provides also information about anticharmed pentaquarks that are seemingly unbound in simple quark models. 
J. Vijande, A. Valcarce, J.-M. Richard, and P. Sorba
hep-ph nucl-th