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Related papers: Complex Langevin and boundary terms

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One reason for the well known fact that the Complex Langevin (CL) method sometimes fails to converge or converges to the wrong limit has been identified long ago: it is insufficient decay of the probability density either near infinity or…

High Energy Physics - Lattice · Physics 2020-01-15 M. Scherzer , E. Seiler , D. Sexty , I. -O. Stamatescu

In complex Langevin simulations, the insufficient decay of the probability density near infinity leads to boundary terms that spoil the formal argument for correctness. We present a formulation of this term that is cheaply measurable in…

High Energy Physics - Lattice · Physics 2021-12-07 Michael W. Hansen , Erhard Seiler , Dénes Sexty , Ion-Olimipu Stamatescu

The Complex Langevin (CL) method to simulate `complex probabilities', ideally produces expectation values for the observables that converge to a limit equal to the expectation values obtained with the original complex `probability' measure.…

High Energy Physics - Lattice · Physics 2023-12-01 Erhard Seiler , Dénes Sexty , Ion-Olimpiu Stamatescu

We discuss the problem of possible boundary terms at poles of the drift in the complex Langevin method, which spoil correctness of the method. For the simplest, however paradigmatic cases we can find complete answers. Lessons for more…

High Energy Physics - Lattice · Physics 2020-11-18 Erhard Seiler

The complex Langevin method is a general method to treat systems with complex action, such as QCD at nonzero density. The formal justification relies on the absence of certain boundary terms, both at infinity and at the unavoidable poles of…

High Energy Physics - Lattice · Physics 2021-11-03 Erhard Seiler

The complex Langevin approach is a promising method for the numerical treatment of systems with a sign problem, for which conventional lattice field theory techniques based on importance sampling cannot be applied. However, complex Langevin…

High Energy Physics - Lattice · Physics 2026-04-15 Michael Mandl

The complex Langevin method (CLM) provides a promising way to perform the path integral with a complex action using a stochastic equation for complexified dynamical variables. It is known, however, that the method gives wrong results in…

High Energy Physics - Lattice · Physics 2016-12-01 Shinji Shimasaki , Keitaro Nagata , Jun Nishimura

Recently the complex Langevin method (CLM) has been attracting attention as a solution to the sign problem, which occurs in Monte Carlo calculations when the effective Boltzmann weight is not real positive. An undesirable feature of the…

High Energy Physics - Lattice · Physics 2018-06-13 Keitaro Nagata , Jun Nishimura , Shinji Shimasaki

In the landscape of approaches toward the simulation of Lattice Models with complex action the Complex Langevin (CL) appears as a straightforward method with a simple, well defined setup. Its applicability, however, is controlled by certain…

High Energy Physics - Lattice · Physics 2018-04-18 Gert Aarts , Kirill Boguslavski , Manuel Scherzer , Erhard Seiler , Dénes Sexty , Ion-Olimpiu Stamatescu

The method of complex Langevin simulations is a tool that can be used to tackle the complex-action problem encountered, for instance, in finite-density lattice quantum chromodynamics or real-time lattice field theories. The method is based…

High Energy Physics - Lattice · Physics 2024-10-18 Michael Mandl , Michael W. Hansen , Erhard Seiler , Dénes Sexty

The complex Langevin (CL) method is a classical numerical strategy to alleviate the numerical sign problem in the computation of lattice field theories. Mathematically, it is a simple numerical tool to compute a wide class of…

Numerical Analysis · Mathematics 2020-11-06 Zhenning Cai , Xiaoyu Dong , Yang Kuang

The complex Langevin method is a leading candidate for solving the sign problem occurring in various physical situations, notably QCD at finite chemical potential. Its most vexing problem is `convergence to the wrong limit', where the…

High Energy Physics - Lattice · Physics 2011-10-27 Gert Aarts , Frank A. James , Erhard Seiler , Ion-Olimpiu Stamatescu

The complex Langevin method is a leading candidate for solving the so-called sign problem occurring in various physical situations. Its most vexing problem is that in some cases it produces `convergence to the wrong limit'. In the first…

High Energy Physics - Lattice · Physics 2015-05-27 Gert Aarts , Frank A. James , Erhard Seiler , Ion-Olimpiu Stamatescu

In this review we present the current state-of-the-art on complex Langevin simulations and their implications for the QCD phase diagram. After a short summary of the complex Langevin method, we present and discuss recent developments. Here…

High Energy Physics - Lattice · Physics 2020-10-28 Felipe Attanasio , Benjamin Jäger , Felix P. G. Ziegler

Complex Langevin simulations are an attempt to solve the sign (or complex-action) problem encountered in various physical systems of interest. The method is based on a complexification of the underlying degrees of freedom and an evolution…

High Energy Physics - Lattice · Physics 2025-04-08 Michael W. Hansen , Michael Mandl , Erhard Seiler , Dénes Sexty

The Complex Langevin (CL) method sometimes shows convergence to the wrong limit, even though the Schwinger-Dyson Equations (SDE) are fulfilled. We analyze this problem in a more general context for the case of one complex variable. We prove…

Mathematical Physics · Physics 2018-12-17 Lorenzo Luis Salcedo , Erhard Seiler

We discuss recent developments regarding the use of kernels in complex Langevin simulations. In particular, we outline how a kernel can be used to solve the problem of wrong convergence in a simple toy model. Since conventional correctness…

High Energy Physics - Lattice · Physics 2025-12-17 Michael Mandl , Erhard Seiler , Dénes Sexty

Complex Langevin (CL) is a computational method to circumvent the numerical sign problem with applications in finite-density quantum chromodynamics and the real-time dynamics of quantum field theories. It has long been known that, depending…

High Energy Physics - Lattice · Physics 2025-03-24 Kirill Boguslavski , Paul Hotzy , David I. Müller

The complex Langevin method is a promising approach to the complex-action problem based on a fictitious time evolution of complexified dynamical variables under the influence of a Gaussian noise. Although it is known to have a restricted…

High Energy Physics - Lattice · Physics 2017-01-04 Keitaro Nagata , Jun Nishimura , Shinji Shimasaki

We simulate lattice QCD at finite quark-number chemical potential to study nuclear matter, using the complex Langevin equation (CLE). The CLE is used because the fermion determinant is complex so that standard methods relying on importance…

High Energy Physics - Lattice · Physics 2018-04-18 D. K. Sinclair , J. B. Kogut
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