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Related papers: Complex Langevin calculations in QCD at finite den…

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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 study lattice QCD at non-vanishing chemical potential using the complex Langevin equation. We compare the results with multi-parameter reweighting both from $\mu=0$ and phase quenched ensembles. We find a good agreement for lattice…

High Energy Physics - Lattice · Physics 2015-12-02 Z. Fodor , S. D. Katz , D. Sexty , C. Török

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

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 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

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

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

In this paper we test the complex Langevin algorithm for numerical simulations of a random matrix model of QCD with a first order phase transition to a phase of finite baryon density. We observe that a naive implementation of the algorithm…

High Energy Physics - Lattice · Physics 2018-04-04 J. Bloch , J. Glesaaen , J. J. M. Verbaarschot , S. Zafeiropoulos

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

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 present results of a simulation of QCD on a 4x16^3 lattice with 2 continuum flavors of p4-improved staggered fermion with mass m/T=0.4. Derivatives of the thermodynamic grand potential with respect to quark chemical potential mu_q up to…

High Energy Physics - Lattice · Physics 2011-05-05 C. R. Allton , S. Ejiri , S. J. Hands , O. Kaczmarek , F. Karsch , E. Laermann , C. Schmidt

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

Charting the phase diagram of Quantum Chromodynamics (QCD) at large density is a challenging task due to the complex action problem in lattice simulations. Through simulations at imaginary baryon chemical potential $\mu_B$ we observe that,…

High Energy Physics - Lattice · Physics 2025-11-03 Szabolcs Borsányi , Zoltán Fodor , Jana N. Guenther , Piyush Kumar , Paolo Parotto , Attila Pásztor , Chik Him Wong

We present the computation of invariants that arise in the strong coupling expansion of lattice QCD. These invariants are needed for Monte Carlo simulations of Lattice QCD with staggered fermions in a dual, color singlet representation.…

High Energy Physics - Lattice · Physics 2018-04-18 Giuseppe Gagliardi , Jangho Kim , Wolfgang Unger

We compute the quark number susceptibilities in two flavor QCD for staggered fermions by adding the chemical potential as a Lagrange multiplier for the point-split number density term. Since lesser number of quark propagators are required…

High Energy Physics - Lattice · Physics 2014-11-21 R. V. Gavai , Sayantan Sharma

At sufficiently high temperature and density, quantum chromodynamics (QCD) predicts phase transition from the hadronic phase to the quark-gluon plasma phase. Lattice QCD is the most useful tool to investigate this critical phenomenon, which…

High Energy Physics - Phenomenology · Physics 2017-08-23 Xiang-Qian Luo , Eric B. Gregory , Shuo-Hong Guo , Helmut Kroger

Approaches to finite baryon density lattice QCD usually suffer from uncontrolled systematic uncertainties in addition to the well-known sign problem. We test a method - sign reweighting - that works directly at finite chemical potential and…

High Energy Physics - Lattice · Physics 2021-12-09 Attila Pasztor , Szabolcs Borsanyi , Zoltan Fodor , Kornel Kapas , Sandor D. Katz , Matteo Giordano , Daniel Nogradi , Chik Him Wong

We propose a method to probe the nature of phase transitions in lattice QCD at finite temperature and density, which is based on the investigation of an effective potential as a function of the average plaquette. We analyze data obtained in…

High Energy Physics - Lattice · Physics 2008-11-26 Shinji Ejiri

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

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