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The Darwin field model addresses an approximation to Maxwell's equations where radiation effects are neglected. It allows to describe general quasistatic electromagnetic field phenomena including inductive, resistive and capacitive effects.…

Computational Engineering, Finance, and Science · Computer Science 2020-03-13 Markus Clemens , Bernhard Kähne , Sebastian Schöps

In this work a Feynman-Kac path integral method based on Levy measure has been proposed for solving the Cauchy problems associated with the space-time fractional Schroedinger equations arising in interacting systems in fractional quantum…

Quantum Physics · Physics 2023-06-27 Sumita Datta , Radhika Prosad Datta

We apply constant imaginary offsets to the path integral for a reduction of the sign problem in the Hubbard model. These simple transformations enhance the quality of results from HMC calculations without compromising the speed of the…

Strongly Correlated Electrons · Physics 2024-07-11 Christoph Gäntgen , Evan Berkowitz , Thomas Luu , Johann Ostmeyer , Marcel Rodekamp

Simulations of supersymmetric field theories on the lattice with (spontaneously) broken supersymmetry suffer from a fermion sign problem related to the vanishing of the Witten index. We propose a novel approach which solves this problem in…

High Energy Physics - Lattice · Physics 2015-09-07 David Baumgartner , Urs Wenger

We develop a way of improving complex Langevin dynamics motivated by the Lefschetz-thimble decomposition of integrals. In our method, arbitrary observables of an original model with multiple Lefschetz thimbles are computed by a modified…

High Energy Physics - Lattice · Physics 2016-10-12 Shoichiro Tsutsui , Takahiro M. Doi

As an intrinsically-unbiased approach, quantum Monte Carlo (QMC) is of vital importance in understanding correlated phases of matter. Unfortunately, it often suffers notorious sign problem when simulating interacting fermion models. Here,…

Strongly Correlated Electrons · Physics 2022-11-03 Zi-Xiang Li , Zhou-Quan Wan , Hong Yao

In recent years, there has been remarkable progress in theoretical justification of the complex Langevin method, which is a promising method for evading the sign problem in the path integral with a complex weight. There still remains,…

High Energy Physics - Lattice · Physics 2015-12-09 Jun Nishimura , Shinji Shimasaki

A novel finite element method for the approximation of Maxwell's equations over hybrid two-dimensional grids is studied. The choice of appropriate basis functions and numerical quadrature leads to diagonal mass matrices which allow for…

Numerical Analysis · Mathematics 2022-09-22 Herbert Egger , Bogdan Radu

A second order accurate, linear numerical method is analyzed for the Landau-Lifshitz equation with large damping parameters. This equation describes the dynamics of magnetization, with a non-convexity constraint of unit length of the…

Numerical Analysis · Mathematics 2021-11-16 Yongyong Cai , Jingrun Chen , Cheng Wang , Changjian Xie

We address the problem of the minus sign sampling for two electron systems using the path integral approach. We show that this problem can be reexpressed as one of computing free energy differences and sampling the tails of statistical…

Quantum Physics · Physics 2018-10-10 Johan Runeson , Marco Nava , Michele Parrinello

We study the two dimensional lattice Thirring model in the presence of a fermion chemical po- tential. Our model is asymptotically free, contains massive fermions that mimic a baryon and light bosons that mimic pions. Hence it is a useful…

High Energy Physics - Lattice · Physics 2018-03-14 Venkitesh Ayyar , Shailesh Chandrasekharan , Jarno Rantaharju

Simulations of supersymmetric models on the lattice with (spontaneously) broken supersymmetry suffer from a fermion sign problem related to the vanishing of the Witten index. We propose a novel approach which solves this problem in low…

High Energy Physics - Lattice · Physics 2011-04-04 David Baumgartner , Urs Wenger

The path-integral calculation for the free energy of a spin-1/2 Dirac-fermion gas is performed in spherical polar coordinates for a flat spacetime geometry. Its equivalence with the Cartesian-coordinate representation is explicitly…

High Energy Physics - Theory · Physics 2013-07-08 Andrew Briggs , Horacio E. Camblong , Carlos R. Ordonez

Recently, cluster methods have been used to solve a variety of sign problems including those that arise in the presence of fermions. In all cases an analytic partial re-summation over a class of configurations in the path integral was…

High Energy Physics - Lattice · Physics 2009-10-31 Shailesh Chandrasekharan

Lobachewsky geometry simulates a medium with special constitutive relations. The situation is specified in quasi-cartesian coordinates (x,y,z). Exact solutions of the Maxwell equations in complex 3-vector form, extended to curved space…

Mathematical Physics · Physics 2011-09-02 E. M. Ovsiyuk , V. M. Red'kov

The calculation of the ground state and thermodynamics of mass-imbalanced Fermi systems is a challenging many-body problem. Even in one spatial dimension, analytic solutions are limited to special configurations and numerical progress with…

Quantum Gases · Physics 2018-07-20 Lukas Rammelmüller , William J. Porter , Joaquín E. Drut , Jens Braun

As an intrinsically unbiased method, the quantum Monte Carlo (QMC) method is of unique importance in simulating interacting quantum systems. Although the QMC method often suffers from the notorious sign problem, the sign problem of quantum…

Strongly Correlated Electrons · Physics 2023-08-03 Zhou-Quan Wan , Shi-Xin Zhang , Hong Yao

We develop transportation-entropy inequalities which are saturated for measures such that their log-density with respect to the background measure is an affine function, in the setting of the uniform measure on the discrete hypercube and…

Probability · Mathematics 2019-03-20 Fanny Augeri

We propose a new approach to the fermion sign problem in systems where there is a coupling $U$ such that when it is infinite the fermions are paired into bosons and there is no fermion permutation sign to worry about. We argue that as $U$…

High Energy Physics - Lattice · Physics 2014-11-20 Shailesh Chandrasekharan

Path integral Monte Carlo (PIMC) simulations are used to calculate the momentum distribution of the homogeneous electron gas at finite temperature. This is done by calculating the off-diagonal elements of the real-space density matrix,…

Statistical Mechanics · Physics 2007-05-23 B. Militzer , E. L. Pollock , D. M. Ceperley