The field of multiquark states has been catalyzed in recent years by new experimental and theoretical advances relating to four, five and six quark systems. Significant recent progress has been made in the 6q sector (referred to as the dibaryons or hexaquarks). The existence of dibaryons based on six non-strange quarks has been postulated from theoretical studies based on SU(6) symmetry, with the earliest work by Dyson and Xoung in the 1960’s. Recent results based on perturbative quark based models and the developing lattice-QCD calculations are leading to a significant improvement in our understanding of di-baryonic physics.
On the experimental side significant information has been obtained from hadronic beams (CELSIUS, COSY, GSI). The dibaryon sextet has been investigated via a number of final states, with information on the isotensor dibaryon and setting limits on isospin I=3 state obtained only last year.
Electromagnetic probes have the potential to provide new information and a deeper insight into dibaryonic physics. The latest results from the ELPH and MAMI facilities confirm the feasibility of dibaryon production in photo-induced reactions. The clean and controlled environment of electromagnetic beams may enable the size and internal structure of di-baryonic states to be elucidated. Such programmes may also enable important constraints on N-N* interaction dynamics – extending our knowledge of the nucleon-nucleon interaction beyond the ground state interactions.
The potential role of di-baryonic states in astrophysics has given recent added impetus to the programme. Recent theoretical works have indicated that the lightest dibaryons may have a significant impact on neutron star properties, influencing the equation of state, cooling mechanisms and maximum mass limits.
This talk will give an overview of all the recent scientific advances in the dibaryon sector along with some plans for the future direction of the programme.