Fermion Systems in Discrete Space-Time - Outer Symmetries and Spontaneous Symmetry Breaking

A Unified Scheme for Generalized Sectors based on Selection Criteria. II. Spontaneously broken symmetries and some basic notions in quantum measurements

Continuing the analysis in a unified scheme for treating generalized superselection sectors based upon the notion of selection criteria for states of relevance in quantum physics, we extend the Doplicher-Roberts superselection theory for recovering the field algebra and the gauge group (of the first kind) from the data of group invariant observables to the situations with spontaneous symmetry breakdown: in use of the machinery proposed, the basic structural features of the theory with spontaneously broken symmetry, are clarified in a clear-cut way, such as the degenerate vacua parametrized by …

Spontaneous Breaking of Gauge Groups to Discrete Symmetries

Many models of beyond Standard Model physics connect flavor symmetry with a discrete group. Having this symmetry arise spontaneously from a gauge theory maintains compatibility with quantum gravity and can be used to systematically prevent anomalies. We minimize a number of Higgs potentials that break gauge groups to discrete symmetries of interest, and examine their scalar mass spectra.

Stable configuration of a molecule as spontaneous symmetry breaking

In a molecule subjected to no external fields, motion of nuclei is governed by a function V of nuclear coordinates. This function (potential energy) is a sum of two terms: Coulomb repulsion between nuclei and the electronic effective potential E which results from the Born-Oppenheimer approximation. In this paper we have presented a group of coordinate transformations which are the symmetries of functions E and V. We showed that the formula for dynamical representation, which has fundamental importance in the symmetry analysis of normal modes of a molecule, follows from these symmetries. In ad…

A Unified Scheme for Generalized Sectors based on Selection Criteria --Order parameters of symmetries and of thermality and physical meanings of adjunctions--

A unified scheme for treating generalized superselection sectors is proposed on the basis of the notion of selection criteria to characterize states of relevance to each specific domain in quantum physics, ranging from the relativistic quantum fields in the vacuum situations with unbroken and spontaneously broken internal symmetries, through equilibrium and non-equilibrium states to some basic aspects in measurement processes. This is achieved by the help of c-q and q-c channels: the former determines the states to be selected and to be parametrized by the order parameters, and the latter prov…

Spontaneous Symmetry Breaking during Formation of ZnO Nanocrystals

Systemic symmetry is introduced into our work to investigate the symmetries of different ZnO nanocrystals. Result shows that systemic symmetries obey the law of spontaneous symmetry breaking during the formation of ZnO nanocrystals. A unitary formation mechanism of ZnO nanocrystals is proposed accordingly. Our results provide new insight into both crystallization and spontaneous symmetry breaking at meso-scale.

有序相中的涌现广义对称性及其在量子无序化中的应用

Emergent generalized symmetries in ordered phases and applications to quantum disordering

本研究探究有序相低能下涌现的高阶形式与不可逆对称性，揭示其缺陷由(D-1)群表示描述，破缺可引发含拓扑序的相变，还存在与微观对称性的混合反常，为表征相及相变提供框架。