Scott Bogner
NSCL/FRIB & Michigan State University

Heiko Hergert
NSCL/FRIB & Michigan State University

Ragnar Stroberg
University of Washington

Diversity Coordinator:

Heiko Hergert
NSCL/FRIB & Michigan State University

Program Coordinator:
(206) 685-3360

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INT Workshop INT-20-78W

Renormalization Group Approaches to the Many-Body Problem

November 16 - 20, 2020

Update: Due to the COVID-19 pandemic, the workshop program plan has been revised accordingly to become an online virtual workshop.

Modern developments in nuclear theory, condensed matter theory, and quantum chemistry rely on a diverse range of renormalization group (RG) methods. In low energy nuclear physics, Similarity Renormalization Group (SRG) methods have played a leading role in the explosive progress in ab-initio nuclear structure theory over the past decade, helping to push calculations to heavier systems and link successful phenomenology (e.g., the nuclear shell model) to the underlying microscopic degrees of freedom. At higher energies and finite temperature, Functional Renormalization Group (FRG) methods provide powerful non-perturbative analytic and numerical tools to explore non-equilibrium properties and universality in QCD and gauge theories, as well as gravity, ultracold quantum gases, and a diverse range of strongly correlated many-body systems. Density Matrix Renormalization Group (DMRG) and Tensor Network Renormalization Group (TRG) methods, aided by the recent influx of ideas from quantum information theory, have revolutionized the study of low-dimensional lattice spin systems and provided quantum chemists an efficient compromise between accuracy and computational cost to treat static, collective correlations in complicated multi-reference problems.

Despite obvious points of connection between these different classes of RG methods, interactions between practitioners working in the different subfields has been limited. Thus, the overarching purpose of the workshop is to provide a forum for such interactions, which will allow our communities

  1. To communicate both the current state of the art and limitations for RG methods across the different sub-disciplines,

  2. To stimulate the exchange of theoretical and computational techniques, and

  3. To identify possible topics for future cross-disciplinary collaboration, including more focused and in-depth meetings down the road (e.g., at next year’s program on Tensor Networks in Many-Body and Quantum Field Theory).

Some of the specific questions we seek to address concern the combination of RG techniques to overcome limitations of individual approaches. For example,

  • Can one combine SRG and DMRG/TNRG techniques to respectively deal with dynamic (few-body) and static (collective) correlations in multi-reference quantum systems (e.g., open-shell nuclei) in an optimally efficient way that avoids the inherent limitations of exact diagonalization?

  • Conversely, can DMRG or TRG benefit from using SRG transformations to disentangle long- and short-range correlations in lattice systems?

  • Can the link between SRG and FRG methods be clarified, opening up the arsenal of functional methods (Monte Carlo integration, loop expansions, background field methods, natural formalisms for dealing with symmetry breaking, etc.) for SRG calculations of nuclei and nuclear matter?

  • Can SRG and FRG methods, analogous to recent developments in DMRG and TNRG methods, benefit by leveraging ideas from the rapidly growing fields of quantum information theory and quantum computing?

Invited Speakers