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Complex Langevin simulations have been able to successfully reproduce results from Monte Carlo methods in the region where the sign problem is mild and make predictions when it is exponentially hard. We present here our study of the QCD…

High Energy Physics - Lattice · Physics 2016-10-25 Gert Aarts , Felipe Attanasio , Benjamin Jäger , Dénes Sexty

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

We investigate the thermal properties of interacting spin-orbit coupled bosons with contact interactions in two spatial dimensions. To that end, we implement the complex Langevin method, motivated by the appearance of a sign problem, on a…

Quantum Gases · Physics 2020-04-01 Felipe Attanasio , Joaquín E. Drut

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 recent progress in understanding the mathematics of complex stochastic quantization, as well as its application to quantum chromodynamics in situations that have a complex phase problem (e.g. finite quark density, real time), has opened…

Quantum Gases · Physics 2018-08-01 J. E. Drut

Quantitative numerical analyses of interacting dilute Bose-Einstein condensates are most often based on semi-classical approximations. Since the complex-valued field-theoretic action of the Bose gas does not offer itself to the direct…

Quantum Gases · Physics 2023-05-25 Philipp Heinen , Thomas Gasenzer

We study QCD at finite density and low temperature by using the complex Langevin method. We employ the gauge cooling to control the unitarity norm and introduce a deformation parameter in the Dirac operator to avoid the singular-drift…

High Energy Physics - Lattice · Physics 2018-04-18 Keitro Nagata , Jun Nishimura , Shinji Shimasaki

We show that complex Langevin simulation converges to a wrong result, by relating it to the Lefschetz-thimble path integral, when the path-integral weight has different phases among dominant complex saddle points. Equilibrium solution of…

High Energy Physics - Lattice · Physics 2017-02-07 Tomoya Hayata , Yoshimasa Hidaka , Yuya Tanizaki

We propose two novel formulations of the hopping parameter expansion for finite density QCD using Wilson fermions, while keeping the gauge action intact. We use the complex Langevin equation to circumvent the sign problem in the theory. We…

High Energy Physics - Lattice · Physics 2015-03-31 G. Aarts , E. Seiler , D. Sexty , I. -O. Stamatescu

We employ the Complex Langevin method for simulation of complex-valued actions. First, we show how to test for convergence of the method by explicitely computing boundary terms and demonstrate this in a model. Then we investigate the…

High Energy Physics - Lattice · Physics 2018-10-30 Manuel Scherzer , Erhard Seiler , Dénes Sexty , Ion-Olimpiu Stamatescu

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

A method is developed which speeds up averaging in quantum simulations where minus signs cause difficulties. A Langevin equation method in conjunction with a replication algorithm is used enabling one to average over a continuously varying…

comp-gas · Physics 2009-10-22 J. M. Deutsch

Monte Carlo methods cannot probe far into the QCD phase diagram with a real chemical potential, due to the famous sign problem. Complex Langevin simulations, using adaptive step-size scaling and gauge cooling, are suited for sampling path…

High Energy Physics - Lattice · Physics 2015-11-02 Gert Aarts , Felipe Attanasio , Benjamin Jäger , Erhard Seiler , Dénes Sexty , Ion-Olimpiu Stamatescu

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

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

I review the status of the Complex Langevin method, which was invented to make simulations of models with complex action feasible. I discuss the mathematical justification of the procedure, as well as its limitations and open questions.…

High Energy Physics - Lattice · Physics 2018-04-18 Erhard Seiler

I review the presence of the sign problem in lattice QCD at nonzero baryon density and its relation with the overlap and Silver Blaze problems. I then discuss progress in some cases where the sign problem can be handled, either because the…

High Energy Physics - Lattice · Physics 2013-03-05 Gert Aarts

At nonzero chemical potential the numerical sign problem in lattice field theory limits the use of standard algorithms based on importance sampling. Complex Langevin dynamics provides a possible solution, but it has to be applied with care.…

High Energy Physics - Lattice · Physics 2015-06-15 Gert Aarts , Lorenzo Bongiovanni , Erhard Seiler , Denes Sexty , Ion-Olimpiu Stamatescu

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

It is well known that investigating QCD at finite density by standard Monte Carlo methods is extremely difficult due to the sign problem. Some years ago, the complex Langevin method with gauge cooling was shown to work at high temperature,…

High Energy Physics - Lattice · Physics 2019-01-15 Keitaro Nagata , Jun Nishimura , Shinji Shimasaki