Session B00: Plenary Session

Science and Status of the Electron Ion Collider – A new collider is coming to our neighborhood

Quantum Chromodynamics (QCD) is the theory of Strong Interactions within the Standard Model of Physics which has been tested extensively and proved to be correct. A Nobel Prize was awarded in 2004. The force carrier of strong interactions – the gluon – binds the quarks inside hadrons. Unlike its electro-magnetic counterpart, the photon, the gluons carry color-charge and hence it can interact with other gluons. This critical difference creates all the richness of QCD, but some fundamental questions remain unanswered: for example, how do quarks and gluons form a proton? What constitutes proton’s spin, mass starting from the quark-gluon interactions. Unfortunately, this is largely an open question. We still don’t know how those interactions might be at the base of nuclear forces. Since gluons carry color charge, they can interact with other gluons (a phenomena called gluon self-interactions), which according to the current understanding of QCD should lead to initially an aggressive growth in gluon number in a hadron followed by a taming of the same, resulting in a saturated gluonic state of matter. Does it really exist? If so, what its properties? This novel form of matter, often called Color Glass Condensate, so far remains elusive. Why? What would it take to discover such saturated gluonic state of matter? These and such questions were evaluated by the National Academy to “compelling, worth pursuing and timely” by the National Academy in July 2018. The experimental facility that is needed to answer these questions – the Electron Ion collider (EIC) now is being built at Brookhaven National Laboratory (BNL) on Long Island NY – in our neighborhood -- as a joint effort between BNL and Jefferson Laboratory funded by Department of Energy, Office of Nuclear Physics. In this talk I will summarize the EIC science and its status.   

Artificial Spin Ice: A Playground for Frustration

Artificial spin ice consists of arrays of interacting lithographically fabricated single-domain ferromagnetic elements, arranged in different geometries such that the magnetostatic interactions among the moments can be frustrated. We both design the lattice geometries and probe the individual microscopic moments, enabling us to study the accommodation of frustration with exquisite detail and flexibility. Because we conduct experiments on frustrated lattice geometries that are inaccessible in other systems, we can observe and study behavior such as strings of magnetic excitations and entropically induced long-range ordering. Artificial spin ice structures also allow studies of a range of other phenomena, including avalanche statistics, monopole-like charge excitations, and quadrupolar ordering, all of which can be probed microscopically in real space.