Complex Langevin: Boundary terms and application to QCD

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 deconfinement phase transition of QCD with $N_f=2$ Wilson-fermions using the Complex Langevin Method and. We give preliminary results for the transition temperatures up to $\mu/T_c(\mu=0)\approx 5$ and compute the curvature coefficient $\kappa_2$.Comment: Proceedings for The 36th Annual International Symposium on Lattice Field Theory - LATTICE2018; update: added some acknowledgement

Phase transitions in lattice gauge theories: From the numerical sign problem to machine learning

Lattice simulations of Quantum chromodynamics (QCD) are an important tool of modern quantum field theory. They provide high precision results from first principle computations and as such allow for comparison between experiment and theory. At finite baryon density, such simulations are no longer possible due to the numerical sign problem which occurs when the action of the theory becomes complex, leading to integrals over highly oscillatory functions. We investigate two approaches to solve this problem. We employ complex Langevin method, which is a complexified stochastic process and investigate its properties. We apply it to QCD in a region where other methods are unreliable, we go up to $\mu/T_c\approx 5$. We finally investigate its applicability for SU(2) real-time simulations. We also investigate the Lefschetz Thimble method, which solves the sign problem by deforming the manifold of integration, such that there is no more oscillatory behavior. We discuss aspects of the method in simple models and develop algorithms for higher dimensions.\\ Finally, we apply neural networks to lattice simulation data and use them to extract the order parameter for the phase transition in the Ising model and SU(2) gauge theory. Thus, we uncover what the neural network learns

Influence of IL28B Polymorphisms on Response to a Lower-Than-Standard Dose peg-IFN-α 2a for Genotype 3 Chronic Hepatitis C in HIV-Coinfected Patients

Background: Data on which to base definitive recommendations on the doses and duration of therapy for genotype 3 HCV/HIV-coinfected patients are scarce. We evaluated the efficacy of a lower peginterferon-α 2a dose and a shorter duration of therapy than the current standard of care in genotype 3 HCV/HIV-coinfected patients. Methods and Findings: Pilot, open-label, single arm clinical trial which involved 58 Caucasian HCV/HIV-coinfected patients who received weekly 135 μg peginterferon-α 2a plus ribavirin 400 mg twice daily during 20 weeks after attaining undetectable viremia. The relationships between baseline patient-related variables, including IL28B genotype, plasma HCV-RNA, ribavirin dose/kg, peginterferon-α 2a and ribavirin levels with virological responses were analyzed. Only 4 patients showed lack of response and 5 patients dropped out due to adverse events related to the study medication. Overall, sustained virologic response (SVR) rates were 58.3% by intention-to-treat and 71.4% by per protocol analysis, respectively. Among patients with rapid virologic response (RVR), SVR and relapses rates were 92.6% and 7.4%, respectively. No relationships were observed between viral responses and ribavirin dose/kg, peginterferon-α 2a concentrations, ribavirin levels or rs129679860 genotype. Conclusions: Weekly 135 μg pegIFN-α 2a could be as effective as the standard 180 μg dose, with a very low incidence of severe adverse events. A 24-week treatment duration appears to be appropriate in patients achieving RVR, but extending treatment up to just 20 weeks beyond negativization of viremia is associated with a high relapse rate in those patients not achieving RVR. There was no influence of IL28B genotype on the virological responses. © 2012 López-Cortés et al.Funding provided by Fundación Pública Andaluza para la gestión de la Investigación en Salud de Sevilla. Hospitales Universitarios Virgen del Rocío. Seville, Spain. The enzyme-linked immunosorbent assay Hu-INF-α kits for determination of pegIFN-α-2a were financed by Roche Pharma, S.A. (Spain).Peer Reviewe

Getting even with CLE

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 specific conditions which are not always satisfied. We here discuss the procedures to meet these conditions and the estimation of systematic errors and present some actual achievements. 35th International Symposium on Lattice Field Theor