A Variational Fit to the Lattice Energy of Two Heavy-Light Mesons

Recent lattice calculations on the interaction energy of two heavy-light mesons (Q 2 ¯ q 2 ) are interpreted in terms of the potential of the corresponding single heavy-light meson (Q¯q). This model leads to a large overestimate of the binding compared with the lattice data -- unless the basic Q¯q potential is modified to become a four-quark potential. PACS numbers: 13.75.-n, 25.80.-e, 25.40.V c email: anthony.green@helsinki.fi d email: jmkopone@rock.helsinki.fi e email: petrus@hip.fi 1 Introduction The advent of B-meson factories at SLAC and KEK has increased interest in the structure of -- and interaction between -- B-mesons. Unfortunately, the latter involves a four-quark system that can not yet be treated fully by lattice QCD techniques. For light quark systems containing 2 or 3 quarks there are indications that instantons play an important role in the interaction[1], whereas with heavy quarks -- as in B-mesons -- a potential approach based on gluon exchange seems to be..