Comments on abelian Higgs models and persistent order

A natural question about Quantum Field Theory is whether there is a deformation to a trivial gapped phase. If the underlying theory has an anomaly, then symmetric deformations can never lead to a trivial phase. We discuss such discrete anomalies in Abelian Higgs models in 1+1 and 2+1 dimensions. We emphasize the role of charge conjugation symmetry in these anomalies; for example, we obtain nontrivial constraints on the degrees of freedom that live on a domain wall in the VBS phase of the Abelian Higgs model in 2+1 dimensions. In addition, as a byproduct of our analysis, we show that in 1+1 dimensions the Abelian Higgs model is dual to the Ising model. We also study variations of the Abelian Higgs model in 1+1 and 2+1 dimensions where there is no dynamical particle of unit charge. These models have a center symmetry and additional discrete anomalies. In the absence of a dynamical unit charge particle, the Ising transition in the 1+1 dimensional Abelian Higgs model is removed. These models without a unit charge particle exhibit a remarkably persistent order: we prove that the system cannot be disordered by either quantum or thermal fluctuations. Equivalently, when these theories are studied on a circle, no matter how small or large the circle is, the ground state is non-trivial.

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Where are the degrees of freedom responsible for black-hole entropy?

Canadian Journal of Physics ◽

10.1139/p07-183 ◽

2008 ◽

Vol 86 (4) ◽

pp. 653-658 ◽

Cited By ~ 3

Author(s):

S Das ◽

S Shankaranarayanan ◽

S Sur

Keyword(s):

Black Hole ◽

Excited State ◽

Power Law ◽

Ground State ◽

Degrees Of Freedom ◽

Black Hole Entropy ◽

Quantum Field ◽

Hole Area ◽

Area Law ◽

03.65 Ud

Considering the entanglement between quantum field degrees of freedom inside and outside the horizon as a plausible source of black-hole entropy, we address the question: where are the degrees of freedom that give rise to this entropy located? When the field is in ground state, the black-hole area law is obeyed and the degrees of freedom near the horizon contribute most to the entropy. However, for excited state, or a superposition of ground state and excited state, power-law corrections to the area law are obtained, and more significant contributions from the degrees of freedom far from the horizon are shown.PACS Nos.: 04.60.–m, 04.62., 04.70.–s, 03.65.Ud

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ELECTROWEAK BAU GENERATION ON THE LATTICE: REAL-TIME VS. EUCLIDEAN APPROACH

International Journal of Modern Physics A ◽

10.1142/s0217751x90001987 ◽

1990 ◽

Vol 05 (24) ◽

pp. 4677-4687 ◽

Cited By ~ 2

Author(s):

D. YU. GRIGORIEV ◽

M. E. SHAPOSHNIKOV

Keyword(s):

Real Time ◽

Early Universe ◽

High Temperatures ◽

Ground State ◽

Gauge Theories ◽

Numerical Technique ◽

Higgs Model ◽

Abelian Higgs Model ◽

Fermion Number ◽

Real Time Simulations

We discuss possible approaches to the investigation of anomalous processes with fermion number nonconservation occurring in the hot early Universe. A real-time numerical technique for studying the ground state of gauge theories at high temperatures is developed. This problem is relevant to the scenario of electroweak BAU generation and some other topics. We present the results of real-time simulations of the Abelian Higgs model in (1 + 1) dimensions.

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THE TWO-DIMENSIONAL CHIRAL HIGGS MODEL

Modern Physics Letters A ◽

10.1142/s0217732391003663 ◽

1991 ◽

Vol 06 (34) ◽

pp. 3171-3177

Author(s):

F. A. SCHAPOSNIK ◽

M. TROBO

Keyword(s):

Partition Function ◽

Degrees Of Freedom ◽

Higgs Model ◽

Two Dimensional ◽

Abelian Higgs Model

We show that the two-dimensional chiral Abelian Higgs model, though anomalous, can be consistently quantized provided that gauge degrees of freedom are adequately taken into account. In this way, the anomaly is canceled by a Wess–Zumino term and as a result, instanton contributions are eliminated from the partition function.

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Quantum gauge transformation, gauge-invariant extension and angular momentum decomposition in Abelian Higgs model

Modern Physics Letters A ◽

10.1142/s0217732318502292 ◽

2018 ◽

Vol 33 (39) ◽

pp. 1850229

Author(s):

Israel Weimin Sun

Keyword(s):

Angular Momentum ◽

Gauge Transformation ◽

Degrees Of Freedom ◽

Gauge Condition ◽

Matter Field ◽

Higgs Model ◽

Gauge Invariant ◽

Abelian Higgs Model ◽

Invariant Extension ◽

Separation Pattern

I discuss the momentum and angular momentum decomposition problem in the Abelian Higgs model. The usual gauge-invariant extension (GIE) construction is incorporated naturally into the framework of quantum gauge transformation à la Strocchi and Wightman and with this, I investigate the momentum and angular momentum separation in a class of GIE conditions which correspond to the so-called “static gauges”. Using this language, I find that the so-called “generator criterion” does not generally hold even for the dressed physical field. In the case of U(1) symmetry breaking, I generalize the standard GIE construction to include the matter field degrees of freedom so that the usual separation pattern of momentum and angular momentum in the unitarity gauge can be incorporated into the same universal framework. When the static gauge condition could not uniquely fix the gauge, I show that this GIE construction should be expanded to take into account the residual gauge symmetry. In some cases, I reveal that the usual momentum or angular momentum separation pattern in terms of the physical dressed field variables needs some type of modification due to the nontrivial commutator structure of the underlying quantum gauge choice. Finally, I give some remarks on the general GIE constructions in connection with the possible commutator issues and modification of momentum and angular momentum separation patterns.

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The role of vortex strings in the non-compact lattice Abelian Higgs model

Physics Letters B ◽

10.1016/0370-2693(96)00396-6 ◽

1996 ◽

Vol 378 (1-4) ◽

pp. 227-232 ◽

Cited By ~ 10

Author(s):

Michael Chavel

Keyword(s):

Higgs Model ◽

Abelian Higgs Model ◽

Compact Lattice

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On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

10.26434/chemrxiv.8870594.v2 ◽

2019 ◽

Author(s):

Riccardo Spezia ◽

Hichem Dammak

Keyword(s):

Degrees Of Freedom ◽

Molecular Simulations ◽

Zero Point ◽

Thermal Bath ◽

Unimolecular Dissociation ◽

Point Energy ◽

Rotational Degrees Of Freedom ◽

The Difference ◽

Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

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Dzyaloshinskii–Moriya interaction in noncentrosymmetric superlattices

npj Computational Materials ◽

10.1038/s41524-021-00592-8 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Woo Seung Ham ◽

Abdul-Muizz Pradipto ◽

Kay Yakushiji ◽

Kwangsu Kim ◽

Sonny H. Rhim ◽

...

Keyword(s):

Heavy Metal ◽

Degrees Of Freedom ◽

Orbit Coupling ◽

Inversion Symmetry ◽

Spin Orbit Coupling ◽

Spin Orbit ◽

Band Formation ◽

Research Activities ◽

Moriya Interaction

AbstractDzyaloshinskii–Moriya interaction (DMI) is considered as one of the most important energies for specific chiral textures such as magnetic skyrmions. The keys of generating DMI are the absence of structural inversion symmetry and exchange energy with spin–orbit coupling. Therefore, a vast majority of research activities about DMI are mainly limited to heavy metal/ferromagnet bilayer systems, only focusing on their interfaces. Here, we report an asymmetric band formation in a superlattices (SL) which arises from inversion symmetry breaking in stacking order of atomic layers, implying the role of bulk-like contribution. Such bulk DMI is more than 300% larger than simple sum of interfacial contribution. Moreover, the asymmetric band is largely affected by strong spin–orbit coupling, showing crucial role of a heavy metal even in the non-interfacial origin of DMI. Our work provides more degrees of freedom to design chiral magnets for spintronics applications.

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A Superfluid Perspective on Neutron Star Dynamics

Universe ◽

10.3390/universe7010017 ◽

2021 ◽

Vol 7 (1) ◽

pp. 17

Author(s):

Nils Andersson

Keyword(s):

Neutron Star ◽

Degrees Of Freedom ◽

Temperature Scale ◽

Fluid System ◽

Fluid Core ◽

State Of Matter ◽

Entrainment Effect ◽

Neutron Component ◽

The Impact

As mature neutron stars are cold (on the relevant temperature scale), one has to carefully consider the state of matter in their interior. The outer kilometre or so is expected to freeze to form an elastic crust of increasingly neutron-rich nuclei, coexisting with a superfluid neutron component, while the star’s fluid core contains a mixed superfluid/superconductor. The dynamics of the star depend heavily on the parameters associated with the different phases. The presence of superfluidity brings new degrees of freedom—in essence we are dealing with a complex multi-fluid system—and additional features: bulk rotation is supported by a dense array of quantised vortices, which introduce dissipation via mutual friction, and the motion of the superfluid is affected by the so-called entrainment effect. This brief survey provides an introduction to—along with a commentary on our current understanding of—these dynamical aspects, paying particular attention to the role of entrainment, and outlines the impact of superfluidity on neutron-star seismology.

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