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Related papers: Simulating full QCD at nonzero density using the c…

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We present a method of simulating lattice QCD at nonzero chemical potential in the chiral limit. By adding a weak four-fermi interaction to the standard staggered fermion SU(3) QCD action, we produce an algorithm in which the limit of…

High Energy Physics - Lattice · Physics 2009-10-28 I. M. Barbour , S. E. Morrison , John B. Kogut

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

Simulations of QCD with a finite chemical potential typically lead to a severe sign problem, prohibiting any standard Monte Carlo approach. Complex Langevin simulations provide an alternative to sample path integrals with oscillating weight…

High Energy Physics - Lattice · Physics 2014-11-12 Gert Aarts , Felipe Attanasio , Benjamin Jäger , Erhard Seiler , Denes Sexty , Ion-Olimpiu Stamatescu

We study full QCD at finite density and low temperature with light quark mass using the complex Langevin method. Since the singular drift problem turns out to be mild on a $4^3 \times 8$ lattice we use, the gauge cooling is performed only…

High Energy Physics - Lattice · Physics 2016-11-28 Keitaro Nagata , Hideo Matsufuru , Jun Nishimura , Shinji Shimasaki

We use complex Langevin simulations to explore the QCD phase diagram over a large range of chemical potentials and temperatures. For our simulations, we use two flavours of dynamical Wilson fermions with a pion mass of approximately…

High Energy Physics - Lattice · Physics 2021-11-04 Felipe Attanasio , Benjamin Jäger , Felix P. G. Ziegler

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

It is demonstrated that the complex Langevin method can simulate chiral random matrix theory at non-zero chemical potential. The successful match with the analytic prediction for the chiral condensate is established through a shift of…

High Energy Physics - Lattice · Physics 2015-03-05 A. Mollgaard , K. Splittorff

The sign problem appears in lattice QCD as soon as a non-zero chemical potential is introduced. This prevents direct simulations to determine the phase structure of the strongly interacting matter. Complex Langevin methods have been…

High Energy Physics - Lattice · Physics 2018-04-18 Felipe Attanasio , Benjamin Jäger

We use the heavy dense formulation of QCD (HD-QCD) as the basis for an analytic expansion as systematic approximation to QCD at non-zero density, keeping the full Yang-Mills action. We analyse the structure of the baryonic density and other…

High Energy Physics - Lattice · Physics 2014-12-19 Gert Aarts , Benjamin Jäger , Erhard Seiler , Denes Sexty , Ion-Olimpiu Stamatescu

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

Recently there has been remarkable progress in the complex Langevin method, which aims at solving the complex action problem by complexifying the dynamical variables in the original path integral. In particular, a new technique called the…

High Energy Physics - Lattice · Physics 2015-12-30 Keitaro Nagata , Jun Nishimura , Shinji Shimasaki

Monte Carlo studies of QCD at finite density suffer from the sign problem, which becomes easily uncontrollable as the chemical potential $\mu$ is increased even for a moderate lattice size. In this work we make an attempt to approach the…

High Energy Physics - Lattice · Physics 2018-12-06 Yuta Ito , Hideo Matsufuru , Jun Nishimura , Shinji Shimasaki , Asato Tsuchiya , Shoichiro Tsutsui

In our previous paper [JHEP 10 (2020) 144], we found that the complex Langevin (CL) method works for QCD at finite density on the $16^3 \times 32$ lattice in the low-temperature high-density regime within the range $\mu / T = 1.6 - 9.6$…

High Energy Physics - Lattice · Physics 2025-10-28 Shoichiro Tsutsui , Yuhma Asano , Yuta Ito , Hideo Matsufuru , Yusuke Namekawa , Jun Nishimura , Shinji Shimasaki , Asato Tsuchiya

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 study a random matrix model for QCD at finite density via complex Langevin dynamics. This model has a phase transition to a phase with nonzero baryon density. We study the convergence of the algorithm as a function of the quark mass and…

High Energy Physics - Lattice · Physics 2017-04-05 Jacques Bloch , Jonas Glesaaen , Owe Philipsen , Jacobus Verbaarschot , Savvas Zafeiropoulos

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

The complex Langevin method is one hopeful candidate to tackle the sign problem. This method is applicable not only to QCD but also to nonrelativistic field theory, such as condensed matter physics. We present the simulation results of a…

High Energy Physics - Lattice · Physics 2015-08-04 Arata Yamamoto , Tomoya Hayata

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

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

The complex Langevin method has been attracting much attention as a solution to the sign problem since the method was shown to work in finite density QCD in the deconfined phase by using the so-called gauge cooling procedure. Whether it…

High Energy Physics - Lattice · Physics 2015-11-30 Keitaro Nagata , Jun Nishimura , Shinji Shimasaki