arXiv subjects
Publications and source records attributed to D. Janc.
We show that the molecule-like configuration of DD^* enables weak binding with two realistic potential models (Bhaduri and Grenoble AL1). Three-body forces may increase the binding and strengthen the cc diquark configuration. As a signature we propose the branching ratio between radiative and pionic decay.
The feasibility of tetraquark detection is studied. For the cc\bar{u}\bar{d} tetraquark we show that in present (SELEX, Tevatron, RHIC) and future facilities (LHCb, ALICE) the production rate is promising and we propose some detectable decay channels.
We critically examine the question whether the cc\bar{q}\bar{q} dimeson is bound or not.
We show that it is necessary to go beyond a single hadron (beyond the quark-antiquark or three-quark systems) in order to distinguish the colour structure of the effective quark-quark interaction and the relevance of 3-body forces. We critically discuss the proposed models which suggest the dimeson bb\bar{u}\bar{d} to be bound by ~ 100 MeV and the cc\bar{u}\bar{d} dimeson to be unbound. Only experiment can judge. We estimate the probability of producing bb-\bar{u}\bar{d} at LHC by double gluon-gluon fusion and search for a characteristic decay.
In the LHC collider a significant rate of events with double parton scattering is expected. This will be the leading mechanism for production of two b-bbar pairs. We estimate the probability of binding two b quarks into a diquark and the probability of dressing this diquark into a b-b-ubar-dbar ISP=01+ tetraquark. Calculations shows that that this bound state of two B mesons is stable against the strong interaction and has a life time of the order of ps. We estimate that the production rate at luminosity L=0.1 events per second will be about 6 tetraquarks per hour or more.
A phenomenological estimate is derived such that the binding energies of dimesons are expressed as combinations of masses of different mesons and baryons. The estimate is almost model-independent, the only major assumptions being that the wave functions of the two light quarks in $Λ_c$, $Λ_b$ and in the $\bar{c}\bar{c}qq$ and $\bar{b}\bar{b}qq$ dimesons are very similar, and that for heavy quarks the $QQ$ interaction is half as strong as the $Q\bar{Q}$ interaction. We get $\bar{b}\bar{b}qq$ (I=0, J=1) bound by about 100 MeV and $\bar{c}\bar{c}qq$ unbound.