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Related papers: Controlling complex Langevin dynamics at finite de…

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The sign problem obstructs the determination of the QCD phase diagram in the temperature-baryon chemical potential plane using lattice QCD. We review the sign problem in QCD and related field theories, including applications to real-time…

High Energy Physics - Lattice · Physics 2026-05-07 Gert Aarts , Dénes Sexty

We first test the Complex Langevin method (CLE) on various simple models. We then introduce the method of Gauge Cooling to control the dynamics of the process and ensure thin distributions in the imaginary direction. We finally apply CLE…

High Energy Physics - Lattice · Physics 2013-10-29 Gert Aarts , Lorenzo Bongiovanni , Erhard Seiler , Denes Sexty , Ion-Olimpiu Stamatescu

The sign problem of QCD prevents standard lattice simulations to determine the phase diagram of strong interactions with a finite chemical potential directly. Complex Langevin simulations provide an alternative method to sample path…

High Energy Physics - Lattice · Physics 2015-06-09 Gert Aarts , Felipe Attanasio , Benjamin Jäger , Erhard Seiler , Dénes Sexty , Ion-Olimpiu Stamatescu

We present our latest results on the application of the complex Langevin method to one- and two-dimensional QCD. Although the method is stable, it unfortunately converges to an incorrect result when applied as such. After applying…

High Energy Physics - Lattice · Physics 2015-08-24 Jacques Bloch , Johannes Mahr , Sebastian Schmalzbauer

The ability to describe strongly interacting matter at finite temperature and baryon density provides the means to determine, for instance, the equation of state of QCD at non-zero baryon chemical potential. From a theoretical point of…

High Energy Physics - Lattice · Physics 2019-01-30 Felipe Attanasio , Benjamin Jäger

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

We study the Stephanov model, which is an RMT model for QCD at finite density, using the Complex Langevin algorithm. Naive implementation of the algorithm shows convergence towards the phase quenched or quenched theory rather than to…

High Energy Physics - Lattice · Physics 2018-04-18 Jacques Bloch , Jonas Glesaaen , Jacobus Verbaarschot , Savvas Zafeiropoulos

Complex Langevin simulations provide an alternative to sample path integrals with complex weights and therefore are suited to determine the phase diagram of QCD from first principles. We use our proposed method of Dynamic Stabilisation (DS)…

High Energy Physics - Lattice · Physics 2016-07-20 Gert Aarts , Felipe Attanasio , Benjamin Jäger , Dénes Sexty

We summarise recent progress in simulating QCD at nonzero baryon density using complex Langevin dynamics. After a brief outline of the main idea, we discuss gauge cooling as a means to control the evolution. Subsequently we present a status…

High Energy Physics - Lattice · Physics 2014-12-03 Gert Aarts , Felipe Attanasio , Benjamin Jäger , Erhard Seiler , Denes Sexty , Ion-Olimpiu Stamatescu

The complex Langevin (CL) method is a promising approach to overcome the sign problem that occurs in real-time formulations of quantum field theories. Using the Schwinger-Keldysh formalism, we study SU($N_c$) gauge theories with CL. We…

High Energy Physics - Lattice · Physics 2023-06-13 Kirill Boguslavski , Paul Hotzy , David I. Müller

Simulations of full QCD at nonzero baryon density using light quark masses are presented. The sign problem is evaded by the usage of the complex Langevin equation. The simulations are stabilized by the gauge cooling procedure for small…

High Energy Physics - Lattice · Physics 2013-10-24 Denes Sexty

The sign problem at nonzero chemical potential prohibits the use of importance sampling in lattice simulations. Since complex Langevin dynamics does not rely on importance sampling, it provides a potential solution. Recently it was shown…

High Energy Physics - Lattice · Physics 2015-06-12 Gert Aarts , Frank A. James , Jan M. Pawlowski , Erhard Seiler , Denes Sexty , Ion-Olimpiu Stamatescu

The complex Langevin method is extended to full QCD at non-zero chemical potential. The use of gauge cooling stabilizes the simulations at small enough lattice spacings. At large fermion mass the results are compared to the HQCD approach,…

High Energy Physics - Lattice · Physics 2014-03-19 Denes Sexty

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

A nonperturbative lattice study of QCD at finite chemical potential is complicated due to the complex fermion determinant and the sign problem. Here we apply the method of stochastic quantization and complex Langevin dynamics to this…

High Energy Physics - Lattice · Physics 2009-02-09 Gert Aarts , Ion-Olimpiu Stamatescu

QCD at non-zero chemical potential ($\mu$) for quark number has a complex fermion determinant and thus standard simulation methods for lattice QCD cannot be applied. We therefore simulate this theory using the Complex-Langevin algorithm…

High Energy Physics - Lattice · Physics 2015-10-22 D. K. Sinclair , J. B. Kogut

A brief overview of the QCD phase diagram at nonzero temperature and density is provided. It is explained why standard lattice QCD techniques are not immediately applicable for its determination, due to the sign problem. We then discuss a…

High Energy Physics - Lattice · Physics 2014-02-06 Gert Aarts

We study the mechanism of the gauge cooling technique to stabilize the complex Langevin method in the one-dimensional periodic setting. In this case, we find the exact solutions for the gauge transform which minimizes the Frobenius norm of…

Numerical Analysis · Mathematics 2020-04-22 Zhenning Cai , Yana Di , Xiaoyu Dong

Non-perturbative formulations of field theories are essential to capture intriguing physical phenomena, including confinement in QCD, spontaneous supersymmetry breaking, and dynamical compactification in superstrings. Lattice regularization…

High Energy Physics - Lattice · Physics 2023-09-08 Arpith Kumar

Recently, the complex Langevin method has been applied successfully to finite density QCD either in the deconfinement phase or in the heavy dense limit with the aid of a new technique called the gauge cooling. In the confinement phase with…

High Energy Physics - Lattice · Physics 2016-08-24 Keitaro Nagata , Jun Nishimura , Shinji Shimasaki