Performance of a worm algorithm in ϕ4\phi^4 theory at finite quartic coupling

Worm algorithms have been very successful with the simulation of sigma models with fixed length spins which result from scalar field theories in the limit of infinite quartic coupling lambda. Here we investigate closer their algorithmic efficiency at finite and even vanishing lambda for the one component model in dimensions D = 2, 3, 4.Comment: 10 pages, 2 Fig

A Quantum Monte Carlo Method at Fixed Energy

In this paper we explore new ways to study the zero temperature limit of quantum statistical mechanics using Quantum Monte Carlo simulations. We develop a Quantum Monte Carlo method in which one fixes the ground state energy as a parameter. The Hamiltonians we consider are of the form $H=H_{0}+\lambda V$ with ground state energy E. For fixed $H_{0}$ and V, one can view E as a function of $\lambda$ whereas we view $\lambda$ as a function of E. We fix E and define a path integral Quantum Monte Carlo method in which a path makes no reference to the times (discrete or continuous) at which transitions occur between states. For fixed E we can determine $\lambda(E)$ and other ground state properties of H

The Problem of Moral Sanctions in the Works of Emile Dukrheim

Цель работы – реконструировать представление о специфике моральных санкций Эмиля Дюркгейма и выявить его место в процессе формирования современной теории моральных санкций. Методология работы определяется установкой на взаимное обогащение историко-этических исследований и теоретического поиска в этике. В соответствии с исходным определением, содержащимся в «Методе социологии», моральная санкция – это «репрессивная диффузная санкция, т.е. осуждение общественным мнением». В статье вскрыто внутреннее противоречие этого определения, состоящее в том, что репрессивный и диффузный характер санкций не означает их тождества с общественным осуждением. Продемонстрированы причины, по которым Э. Дюркгейм склонен все же их отождествлять. Выявлен тот факт, что представление Э. Дюркгейма о моральных санкциях стало важной вехой в формировании той традиции их понимания, в которой они представляют собой осуждение нарушителя моральной нормы окружающими, не переходящее в физическое воздействие на него. В середине XX в. дюркгеймовское понимание моральной санкции было подвергнуто критике как не учитывающее состояние сознания нарушителя (Т. Парсонс, О. Г. Дробницкий). Однако, как показано в статье, в поздних работах Э. Дюркгейма этот недостаток был если не изжит, то, по крайней мере, сглаженThe goal of the paper is to reconstruct Emile Durkheim’s view on the peculiarity of moral sanctions and the place of this view in the development of the contemporary theory of moral sanctions. Methodologically, the paper rests upon the supposition that inquiries in the history of ethical thought can and should enrich the theoretical ethics and vice versa. In the initial definition from Rules of Sociological Method, the moral sanction is a ‘widespread (diffuse) repressive sanction, that is to say a condemnation by public opinion». The paper reveals the inner contradiction of this definition: the repressive and diffuse character of sanction is not the same as its being exclusively a matter of public condemnation. E. Durkheim has some reasons to identify them, and they are analyzed in the paper. The paper also establishes how the Durkheimian sociology of morality contributed to the development of the theoretical tradition that equates moral sanctions with the whole range of expressions of public blame except physically restraining or harming a transgressor. In the middle of the XX‑th century Durkheim’s understanding of moral sanctions was criticized for neglecting the state of mind of a transgressor (T. Parsons, O. G. Drobnitskii). Though the paper shows that this problem was, if not eliminated entirely, at least smoothed out in the later works of E. Durkhei

Finite size scaling and triviality of \phi^4 theory on an antiperiodic torus

Worm methods to simulate the Ising model in the Aizenman random current representation including a low noise estimator for the connected four point function are extended to allow for antiperiodic boundary conditions. In this setup several finite size renormalization schemes are formulated and studied with regard to the triviality of \phi^4 theory in four dimensions. With antiperiodicity eliminating the zero momentum Fourier mode a closer agreement with perturbation theory is found compared to the periodic torus.Comment: 20 pages, 3 double-figures, 6 table

Lattice study of the Silver Blaze phenomenon for a charged scalar phi-4 field

We analyze a complex scalar field with phi-4 interaction and a chemical potential mu on the lattice. An exact flux representation of the partition sum is used which avoids the complex action problem and based on a generalized worm algorithm we can run Monte Carlo simulations at arbitrary densities. We study thermodynamical quantities as a function of the chemical potential mu for zero- and finite temperature. It is shown that at zero temperature thermodynamical observables are independent of mu up to a critical value mu_c (Silver Blaze phenomenon). In a spectroscopy calculation we cross-check that mu_c agrees with the mass m of the scalar field. The Silver Blaze region ends in a second order phase transition and we show that for low temperatures the second order phase boundary persists and separates a pseudo Silver Blaze region from a condensed phase with strong mu-dependence.Comment: Two typos in the appendix fixe

Monte Carlo simulation of the SU(3) spin model with chemical potential in a flux representation

We present a simulation of the SU(3) spin model with chemical potential using a recently proposed flux representation. In this representation the complex phase problem is avoided and a Monte Carlo simulation in terms of the fluxes becomes possible. We explore the phase diagram of the model as a function of temperature and chemical potential