Special Issue "Symmetry Breaking Phenomena"

Assistant Editor
Ms. Laura Simon
MDPI, Kandererstrasse 25, CH-4057 Basel, Switzerland
E-Mail:

Guest Editor
Prof. Dr. Jeroen van den Brink
Institute Lorentz for Theoretical Physics, Leiden University, The Netherlands
Website: http://www.lorentz.leidenuniv.nl/~brink
E-Mail:
Interests: quantum many body systems; quantum decoherence; symmetry breaking; quantum magnetism; quantum compass models; measurement problem; quantum matter

Submission Information

All papers should be submitted to symmetry@mdpi.org. To be published continuously until the deadline and papers will be listed together at the special issue website.

Submitted papers should not have been published nor be under consideration for publication elsewhere. All papers are refereed through a peer-review process. A guide for authors is available on the Instructions for Authors page. Symmetry is a new international, peer-reviewed, quarterly open access journal published by Molecular Diversity Preservation International.

Open Access publication is free of charge for manuscripts submitted in 2009 and published in the first few issues od Symmetry. English correction fees and/or formatting fees of 250 CHF will be billed in certain cases (250 CHF per paper for those papers that require extensive additional formatting and/or English corrections).

• symmetry breaking
• quantum decoherence
• measurement problem

Type of Paper: Review
Title: Spontaneous Symmetry Breaking and Nambu-Goldstone Bosons in Quantum Many-Body Systems
Author: Tomas Brauner
Affiliation: Institute for Theoretical Physics, Goethe University, Max von Laue Strasse 1, 60438 Frankfurt am Main, Germany; E-Mail: brauner@ujf.cas.cz
Abstract: Spontaneous symmetry breaking is a general principle with applications in many areas of physics. It forms the underlying concept of diverse phenomena ranging from ferromagnetism and superconductivity in condensed-matter physics to the Higgs mechanism and mass generation in the Standard model of elementary particles. We focus on manifestations of spontaneously broken symmetries in systems lacking Lorentz invariance, which include both, nonrelativistic systems as well as relativistic systems at finite density. We provide a self-contained review of the properties of spontaneously broken symmetries specific to such theories. Topics covered include: (i) Introduction to the mathematics of spontaneous symmetry breaking and the Goldstone theorem. (ii) Counting of Nambu-Goldstone bosons and their dispersion relations. (iii) Construction of effective Lagrangians. (iv) Examples and applications in both relativistic and nonrelativistic physics.

Title: to be added
Author: Franco Buccella
Affiliation: Dipartimento di Scienze Fisiche, Università di Napoli "Federico II", Mostra d'Oltremare pad.19, I-80125, Napoli, Italy; E-Mail: buccella@na.infn.it
Abstract: In the symmetry breaking pattern for the spontaneous symmetry breaking of gauge unified theories beyond the standard model
a main role is played by the critical orbit of the irreducible representations, for which is easier to construct renormalizable potentials, which are minima on them. Examples will be given for the physically interesting cases of SU(5) and SO(10). For the supersymmetric extension a sufficient condition for the vanishing of the D term has been proven to be necessary, showing the related role of the F term.

Type of Paper: Review
Title: Broken Time Translation Symmetry as a Model for Quantum State Reduction
Author: Jasper van Wezel
Affiliation: T.C.M. Group, Cavendish Laboratory, J. J. Thomson Ave., Cambridge CB3, 0HE, UK; E-Mail: physics@jvanwezel.com
Abstract: The symmetries that govern the laws of nature can be spontaneously broken, enabling the occurrence of ordered states. Crystals arise from the breaking of translation symmetry, magnets from broken spin rotation symmetry and massive particles break a phase rotation symmetry. Time translation symmetry can be spontaneously broken in exactly the same way. The order associated with this form of spontaneous symmetry breaking is characterised by the emergence of quantum state reduction: systems which spontaneously break time translation symmetry act as ideal measurement machines. In this review first compare the breaking of time translation symmetry to that of other symmetries such as spatial translations and rotations. I then discuss how broken time translation symmetry gives rise to the process of quantum state reduction and show how it generates a pointer bases, Born's rule, etc. After a comparison between this model and alternative approaches to the problem of quantum state reduction, I then discuss the experimental implications and possible tests of broken time translation symmetry in realistic experimental settings.

Type of Paper: Article
Title: La₂CuO₄ Properties Predicted by Harttree Fock Symmetry Breaking Effects: Hints for Clarifying the Mott-Slater Debate
Authors: Alejandro Cabo-Bizet¹ and Alejandro Cabo Montes de Oca²
Affiliations: ¹ Departamento de Física, Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Calle 30, esq. a 5ta, La Habana, Cuba
² Grupo de Física Teórica, Instituto de Cibernética Matemática y Física (ICIMAF), Calle E, No. 309, entre 13 y 15, Vedado, La Habana, Cuba; E-Mail: cabo@icmf.inf.cu
Abstract: This work expose in detail the derivations of the results presented in a recent letter, showing that symmetry breaking artree-Fock (HF) solutions of a simple model of the Cu-O planes in La₂CuO₄, are able to predict the insulator and antiferromagnetic characters of this material (See Cabo-Bizet, A. et al. Phys. Lett. 2009, A373,1865). Moreover, pseudogaps HF states also emerged. These surprising results followed after eliminating spin and crystal symmetry constraints usually imposed on the HF orbitals. The discussion helps to clarify the role of the antiferromagnetism and pseudogaps in the physics of the HTSC materials and indicates a promising way to start conciliating the Mott and Slater pictures for the description of the transition metal oxides.
Keywords: symmetry breaking; strongly correlated electron systems; magnetism; HTc supercondutivity; HTSC; pseudgaps; MIS; entanglement

Type of Paper: Article
Title: Dynamical chiral symmetry breaking in QED3 with Abelian
Higgs model
Authors: Jian-Feng Li, Shi-Song Huang, Hong-Tao Feng, Wei-Min Sun and Hong-Shi Zong; E-mail: zonghs@chenwang.nju.edu.cn

Type of Paper: Article
Title: Symmetry Breaking and Structure of a Mixture of Nematic Liquid Crystals and Anisotropic Nanoparticles
Authors: M. Krasna, M. Cvetko, M. Ambrozic, S. Kralj
Affiliation: Regional development agency Mura, Ltd., Lendavska 5a, SI-9000 Murska Sobota Slovenia; E-mail: Matej.Cvetko@rra-mura.si
Abstract: Orientational ordering of a homogeneous mixture of liquid crystalline molecules and magnetic nanoparticles (NPs) is studied using the Lebwohl-Lasher lattice model. Low enough concentrations of NPs are chosen in order to justify absence of phase separation. Temperature fluctuations are neglected and consequently the results are valid deep in the nematic LC phase. The dominant coupling controlling orientational ordering of molecules in solutions originates from elastic interactions. We consider ensembles, which are quenched from the isotropic phase. In order to obtain qualitatively different behavior with respect to behavior of pure components we set that LC molecules and NPs tend to be oriented perpendicularly. A domain-type configurations in orientational ordering are formed following the sudden symmetry breaking isotropic-nematic phase transition. We show that NPs stabilize the domain pattern. For large enough concentrations of NPs the long range nematic ordering is replaced by short range order. The local interactions between NPs and LC molecules give rise to surprisingly strong biaxiality in LC ordering even for relatively low concentrations of NPS.
Keywords: liquid crystals, nanoparticles, orientational order, symmetry breaking, weak disorder

Type of Paper: Review
Title: Topological Defects in Nematic Liquid Crystals
Authors: S. Kralj, M. Cvetko and M. Svetec
Affiliation: Regional development agency Mura, Ltd., Lendavska 5a, SI-9000 Murska Sobota Slovenia; E-mail: Matej.Cvetko@rra-mura.si
Abstract: Topological defects are unavoidable consequence of continuous symmetry breaking. They always appear at least temporary following a fast enough symmetry breaking phase transition. Defect structures can be stabilized by appropriate topological constraints. Because continuous symmetry breaking is ubiquitous in nature defects play vital role in all branches of physics, e.g., in particle physics, condensed matter physics and even in cosmology. Due to universal defect production mechanisms isolated defects, pairs and tangles of defects often display universal behavior. Consequently, it is of interest to find systems in which statics and dynamics of defects could be relatively easily analyzed both experimentally and theoretically. In the review we present such studies in thermotropic nematic liquid crystals, typical soft matter representatives. The bulk nematic phase can be reached by lowering temperature from the isotropic (ordinary liquid) phase. In the former phase in equilibrium the long range orientational ordering along a single symmetry breaking direction is established. We first present coarsening dynamics of defects following a sudden isotropic-nematic quench. In the coarsening process the average length of domain-type texture monotonously increases in time due to annihilation of defects. Then we analyze in detail annihilation of a pair of nematic point defects (monopoles). Finally, we present different core structures of defects. In the last section we relate nematic defects to topological defects in other systems.