Hunt for Exotic Particles: Dibaryons

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The vast majority of the "mass" of visible matter around us is in fact not really mass. It arises from the interaction energy of the components of the proton and neutron, the quarks and gluons. Because of Einstein's famous equivalence of mass and Energy (E=mc^2) the violent interactions of these subatomic particles can generate mass. For the matter around us on Earth and the matter visible in the stars of the night sky these mass generation mechanisms are much more relevant than the mass arising from the recently discovered Higgs, which accounts for less than 1% of the mass of the atomic nucleus. The mechanism of how quarks and gluons are confined into the bound systems of nucleons, which are the building blocks of the nuclei around us, is not well established. The basic theory of how they interact (Quantum Chromo Dynamics or QCD) has been proposed for some time, but how QCD manifests at the scale of the nucleon or other hadrons is not well understood. It is one of the biggest unsolved scientific problem in modern physics. Based on the QCD theory describing how quarks interact (specifically color confinement) one expects that there should be many possible bound states of quarks and gluons. Until very recent years the zoo of bound systems comprised only baryons (qqq) and mesons (qqbar). However in addition the gg and ggg glueball states, tetra-quark systems and possibly pentaquark states are not ruled out by the basic principles of QCD. The field has been revolutionized by the recently discovered system Zc(c cbar d ubar). The race is on to establish the other exotic beasts of QCD which will give a totally new constraint and perspective on the nature of strongly interacting matter. I lead one of the most promising future directions to further our knowledge of the nature of matter, the hunt for dibaryons - mysterious six-quark states.The possibility of exotic dibaryonic states was first proposed by F. Dyson in 1964, just half a year after the Gell-Mann's publication of the quark model. However, this topic received particular attention only after Jaffe's proposal of the so-called H-dibaryon, a uuddss state. I recently led research which has established the existence of a particle made from 6 quarks - the d* dibaryon: a uuuddd state. This is one of the biggest results in the field of strongly interacting matter in the past decade and provides a new window to investigate our understanding of QCD. This exotic object has a high angular momentum, with all six quarks in the ground state having their spins aligned. This d* resonance was investigated in reactions of proton beams on nuclei by the WASA collaboration, largely under my leadership, and is part of an ongoing program. I wish to lead a completely new research branch to investigate this object using beams of high energy photons and electrons to search for it's sister particles. These are the crucial missing piece of the jigsaw needed to unambiguously establish the new exotic particle. I will also establish how the new dibaryon particle interacts with the photon and the electron - it's electromagnetic properties. This will allow the size of the dibaryon to be constrained, enabling the genuine dibaryon with all 6 quarks tightly packed to be distinguished from a molecular-type object with two packages of 3 quarks each.The new field of dibaryon physics will have major impact on a wide range of research areas including primordial nucleosynthesis, star dynamics, dark matter searches and the nature of quark confinement.