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Towards accurate theories of strongly correlated states. Standard model Hubbard model Coulomb gas Heisenberg model Periodic Anderson & Kondo lattice models …. UMass, Amherst. - Introduced in mid 1960s or earlier. - Still not solved. - Admit description in terms of Feynman diagrams.
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Towards accurate theories of strongly correlated states Standard model Hubbard model Coulomb gas Heisenberg model Periodic Anderson & Kondo lattice models … UMass, Amherst - Introduced in mid 1960s or earlier - Still not solved - Admit description in terms of Feynman diagrams
Monte Carlo sampling of fully-dressed irreducible Feynman diagrams up to high-order (10th) + extrapolation to the infinite order limit This is real thing, not a cartoon!
Theory vs experiment (cold unitary fermions solve neutron ) MIT group: Mrtin Zwierlein, Mark Ku, Ariel Sommer, Lawrence Cheuk, Andre Schirotzek Uncertainty due to location of the resonance BDMC results (Umass,Amherst) virial expansion (3d order) Ideal Fermi gas Unbiased solutions beased on millions of graphs with extrapolation to the infinite diagram order From current strong-coupling theories based on one lowest order skeleton graph (MF, RPA, GW, SCBA, GG0, GG, …
Theoretical Model Experimental system ? If predictions fail, who is to blame? wrong model or inaccurate solution? (or the experiment is the suspect )? Analytic methods. Series formulation BDMC for the “rest” Model experimental data Properties of neutron matter: Umass, ITEP, Stony Brook, MIT Coulomb systems (graphene): The entire collaboration Disordered superconductors: Umass, Landau Inst., ISSP