Half-monopole in the Weinberg–Salam model

We present new axially symmetric half-monopole configuration of the SU(2)×U(1) Weinberg–Salam model of electromagnetic and weak interactions. The half-monopole configuration possesses net magnetic charge 2π/e$2\pi /e$ which is half the magnetic charge of a Cho–Maison monopole. The electromagnetic gauge potential is singular along the negative z$z$-axis. However the total energy is finite and increases only logarithmically with increasing Higgs field self-coupling constant λ^1/2${\lambda }^{1/2}$ at sin²θ_W=0.2312${sin}^2{\theta }_W=0.2312$. In the U(1) magnetic field, the half-monopole is just a one dimensional finite length line magnetic charge extending from the origin r=0$r=0$ and lying along the negative z$z$-axis. In the SU(2) ’t Hooft magnetic field, it is a point magnetic charge located at r=0$r=0$. The half-monopole possesses magnetic dipole moment that decreases exponentially fast with increasing Higgs field self-coupling constant λ^1/2${\lambda }^{1/2}$ at sin²θ_W=0.2312${sin}^2{\theta }_W=0.2312$.     

Tricritical point in quantum phase transitions of the Coleman–Weinberg model at Higgs mass

The tricritical point, which separates first and second order phase transitions in three-dimensional superconductors, is studied in the four-dimensional Coleman–Weinberg model, and the similarities as well as the differences with respect to the three-dimensional result are exhibited. The position of the tricritical point in the Coleman–Weinberg model is derived and found to be in agreement with the Thomas–Fermi approximation in the three-dimensional Ginzburg–Landau theory. From this we deduce a special role of the tricritical point for the Standard Model Higgs sector in the scope of the latest experimental results, which suggests the unexpected relevance of tricritical behavior in the electroweak interactions.     

Topological self-dual configurations in a Maxwell–Higgs model with a CPT-odd and Lorentz-violating nonminimal coupling

We have studied the existence of topological self-dual configurations in a nonminimal CPT-odd and Lorentz-violating (LV) Maxwell–Higgs model, where the LV interaction is introduced by modifying the minimal covariant derivative. The Bogomol’nyi–Prasad–Sommerfield formalism has been implemented, revealing that the scalar self-interaction implying self-dual equations contains a derivative coupling. The CPT-odd self-dual equations describe electrically neutral configurations with finite total energy proportional to the total magnetic flux, which differ from the charged solutions of other CPT-odd and LV models previously studied. In particular, we have investigated the axially symmetrical self-dual vortex solutions altered by the LV parameter. For large distances, the profiles possess general behavior similar to the vortices of Abrikosov–Nielsen–Olesen. However, within the vortex core, the profiles of the magnetic field and energy can differ substantially from ones of the Maxwell–Higgs model depending if the LV parameter is negative or positive.     

Critical and Tricritical Wetting in the Two-Dimensional Blume–Capel model

The two-dimensional Blume–Capel model with free surfaces where a surface field \(H_1\) acts and the “crystal field” (controlling the density of the vacancies) takes a value \(D _s\) different from the value \(D\) in the bulk, is studied by Monte Carlo methods. Using a recently developed finite size scaling method that studies thin films in a \(L \times M\) geometry with antisymmetric surface fields \((H_L=-H_1)\) and keeps a generalized aspect ratio \(c = L^2/M\) constant, surface phase diagrams are computed for several typical choices of the parameters. It is shown that both second order and first order wetting transitions occur, separated by tricritical wetting behavior. The special role of vacancies near the surface is investigated in detail.     

Q-balls in the Wick–Cutkosky model

In the present paper Q-ball solutions in the Wick–Cutkosky model are examined in detail. A remarkable feature of the Wick–Cutkosky model is that it admits analytical treatment for the most part of the analysis of Q-balls, which allows one to use this simple model to demonstrate some peculiar properties of Q-balls. In particular, a method for estimating the binding energy of a Q-ball is proposed. This method is tested on the Wick–Cutkosky model taking into account the well-known results obtained for this model earlier.     

Dissipation in Lie–Poisson systems and the Lorenz-84 model

The relation between dissipation and the symplectic structure of the momentum-space is studied in so(3) Lie algebra and in 2D fluid dynamics. Three kinds of dissipative mechanisms are discussed and a general bracket formalism is introduced. A chaotic dynamical system due to Lorenz, and largely studied in low-dimensional models of geophysical fluid dynamics, is analysed in its geometric and dynamical features, by means of the formalism previously introduced. A mechanism of energy transfer for this low-order model is discussed.     

Vortex–shock and vortex–vortex interactions in the compressible starting jet from two beveled nozzle configurations

Journal of Visualization - An experiment was conducted to investigate the flow structures in the compressible starting jet from two beveled nozzles (45 $$^{\circ }$$ and 30 $$^{\circ }$$ nozzle...     

Random-bond and random-anisotropy effects in the phase diagram of the Blume–Capel model

We report on Monte Carlo studies of the influence of quenched randomness on the phase diagram of the three-dimensional (3D) Blume–Capel model. The randomness is supposed to act either on the exchange coupling constants (bond randomness) or on the anisotropy distribution. With increasing disorder, first-order phase transitions are shown to change into second-order phase transitions. The trajectory of the tricritical point in the phase space as a function of disorder is presented. We have also calculated critical exponents at some points in the second-order phase region which show a change of universality class in agreement with the Harris criterion.     

Non-ergodic delocalization in the Rosenzweig–Porter model

Letters in Mathematical Physics - We consider the Rosenzweig–Porter model $$H = V + sqrt{T}, varPhi $$ , where V is a $$N times N$$ diagonal matrix, $$varPhi $$ is drawn from the $$N...     

Supercurrent coupling in the Faddeev–Skyrme model

Motivated by the sigma model limit of multicomponent Ginzburg–Landau theory, a version of the Faddeev–Skyrme model is considered in which the scalar field is coupled dynamically to a one-form field called the supercurrent. This coupled model is investigated in the general setting where physical space M$M$ is an oriented Riemannian manifold and the target space N$N$ is a Kähler manifold, and its properties are compared with the usual, uncoupled Faddeev–Skyrme model. In the case N=S²$N=S^2$, it is shown that supercurrent coupling destroys the familiar topological lower energy bound of Vakulenko and Kapitanski when M=R³$M={\mathbb{R}}^3$, and the less familiar linear bound when M$M$ is a compact 3-manifold. Nonetheless, local energy minimizers may still exist. The first variation formula is derived and used to construct three families of static solutions of the model, all on compact domains. In particular, a coupled version of the unit charge hopfion on a three-sphere of arbitrary radius is found. The second variation formula is derived, and used to analyze the stability of some of these solutions. In particular, it is shown that, in contrast to the uncoupled model, the coupled unit hopfion on the three-sphere of radius R$R$ is unstable   for all R$R$. This gives an explicit, exact example of supercurrent coupling destabilizing a stable solution of the usual Faddeev–Skyrme model, and casts doubt on the conjecture of Babaev, Faddeev and Niemi that knot solitons should exist in the low energy regime of two-component superconductors.     

Gluon shadowing in the Glauber–Gribov model

New data from the HERA experiment on (diffractive) deep inelastic scattering have been used to parameterize the nucleon and pomeron structure functions. Within the Glauber–Gribov model, the parameterizations were employed to calculate gluon shadowing for various heavy ions. We compare our results to predictions from other models. Calculations for d+Au collisions at forward rapidities at ultra-relativistic energies have been made and are compared to RHIC data on the nuclear modification factor. The results for gluon shadowing are also confronted with recent data on the nuclear modification factor at  =17.3 GeV at various values of the Feynman variable x_F, and the energy dependence of the effect is discussed. PACS 12.40.Nn; 13.60.Hb; 13.85.-t; 25.75.-q     

Quasiparticles in the multicomponent Zhang–Hansson–Kivelson model

We study the vortex solutions in a multicomponent Zhang–Hansson–Kivelson model for the fractional quantum Hall effect, at the self-dual point. Vortices with minimal free energy represent Laughlin quasiholes. We find at least two classes of solutions, distinguished by their global invariance, or by the number of conserved charges.     

Higgs bosons in the left–right model

The model with the gauge group, containing one bidoublet and two triplets in the Higgs sector, is considered. The link between the constants determining the physical Higgs boson interactions and the neutrino oscillation parameters is found. It is shown that the observation of the ultrahigh-energy neutrinos with the help of the processes , gives us information on the singly charged Higgs bosons. The processes of the doubly charged Higgs bosons production, , are investigated. From the point of view of detecting the neutral Higgs bosons the process of the electron–muon recharge is studied. Received: 29 January 1999 / Revised version: 20 September 1999 / Published online: 3 February 2000     

On the binding energies and configurations of vacancy and copper–vacancy clusters in bcc Fe–Cu:a computational study

The properties of trapping centres in – as grown – Tl₄GaIn₃S₈ layered single crystals were investigated in the temperature range of 10–300 K using thermoluminescence (TL) measurements. TL curve was analysed to characterize the defects responsible for the observed peaks. Thermal activation energies of the trapping centres were determined using various methods: curve fitting, initial rise and peak shape methods. The results indicated that the peak observed in the low-temperature region composed of many overlapped peaks corresponding to distributed trapping centres in the crystal structure. The apparent thermal energies of the distributed traps were observed to be shifted from ~12 to ~125 meV by increasing the illumination temperature from 10 to 36 K. The analysis revealed that the first-order kinetics (slow retrapping) obeys for deeper level located at 292 meV.