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Nuclear Theory·nucl-th

Thursday·July 25, 2019

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 03

    [Submitted on 19 Jan 2018] (cross-list from physics.ins-det)

    Maximal angular correlation in coincidences: a quantitative study

    Filipe Moura

    The measurement of the angular distribution of maximally correlated annihilation gamma rays radiated in coincidence, like those emitted from a source, is a classic experiment that is nowadays ordinarily performed in Nuclear Physics laboratory classes. For the first time we present an analytic expression for such angular distribution, which can be easily tested and confronted with the laboratory measurements.

    Comments:
    12 pages, 3 figures
    Subjects:
    Instrumentation and Detectors (physics.ins-det); Nuclear Theory (nucl-th)
    arXiv:
    1801.06573 [pdf]
    Am.J.Phys.(2019)·2 citations
  2. 04

    [Submitted on 24 Jul 2019] (cross-list from cond-mat.quant-gas)

    Complex Langevin and other approaches to the sign problem in quantum many-body physics

    Casey E. Berger🇺🇸 · Lukas Rammelmüller🇩🇪 · Andrew C. Loheac🇺🇸 · Florian Ehmann🇩🇪 · Jens Braun🇩🇪 · Joaquín E. Drut🇺🇸

    We review the theory and applications of complex stochastic quantization to the quantum many-body problem. Along the way, we present a brief overview of a number of ideas that either ameliorate or in some cases altogether solve the sign problem, including the classic reweighting method, alternative Hubbard-Stratonovich transformations, dual variables (for bosons and fermions), Majorana fermions, density-of-states methods, imaginary asymmetry approaches, and Lefschetz thimbles. We discuss some aspects of the mathematical underpinnings of conventional stochastic quantization, provide a few pedagogical examples, and summarize open challenges and practical solutions for the complex case. Finally, we review the recent applications of complex Langevin to quantum field theory in relativistic and nonrelativistic quantum matter, with an emphasis on the nonrelativistic case.

    Comments:
    68 pages, 19 figures, review article, version submitted to Physics Reports
    Subjects:
    Quantum Gases (cond-mat.quant-gas); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1907.10183 [pdf]
    Phys.Rept.(2021)·113 citations
  3. 05

    [Submitted on 24 Jul 2019] (cross-list from physics.comp-ph)

    Reducing the complexity of finite-temperature auxiliary-field quantum Monte Carlo

    C.N. Gilbreth · S. Jensen · Y. Alhassid

    The auxiliary-field quantum Monte Carlo (AFMC) method is a powerful and widely used technique for ground-state and finite-temperature simulations of quantum many-body systems. We introduce several algorithmic improvements for finite-temperature AFMC calculations of dilute fermionic systems that reduce the computational complexity of most parts of the algorithm. This is principally achieved by reducing the number of single-particle states that contribute at each configuration of the auxiliary fields to a number that is of the order of the number of fermions. Our methods are applicable for both the canonical and grand-canonical ensembles. We demonstrate the reduced computational complexity of the methods for the homogeneous unitary Fermi gas.

    Comments:
    11 pages, 7 figures, 1 table. Changed page layout and added additional figures, clarifications in the text, and an additional appendix with a derivation of a formula in the main text. The algorithm presented is unchanged
    Subjects:
    Computational Physics (physics.comp-ph); Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
    arXiv:
    1907.10596 [pdf]
    Comput.Phys.Commun.(2021)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE