Vacuum birefringence in strong magnetic fields: (I) Photon polarization tensor with all the Landau levels

Photons propagating in strong magnetic fields are subject to a phenomenon called the “vacuum birefringence” where refractive indices of two physical modes both deviate from unity and are different from each other. We compute the vacuum polarization tensor of a photon in a static and homogeneous magnetic field by utilizing Schwinger’s proper-time method, and obtain a series representation as a result of double integrals analytically performed with respect to proper-time variables. The outcome is expressed in terms of an infinite sum of known functions which is plausibly interpreted as summation over all the Landau levels of fermions. Each contribution from infinitely many Landau levels yields a kinematical condition above which the contribution has an imaginary part. This indicates decay of a sufficiently energetic photon into a fermion–antifermion pair with corresponding Landau level indices. Since we do not resort to any approximation, our result is applicable to the calculation of refractive indices in the whole kinematical region of a photon momentum and in any magnitude of the external magnetic field.     

Semiclassical and quantum motions on the non-commutative plane

We study the canonical and the coherent state quantizations of a particle moving in a magnetic field on the non-commutative plane. Using a θ-modified action, we perform the canonical quantization and analyze the gauge dependence of the theory. We compare coherent states quantizations obtained through Malkin-Man'ko states and circular squeezed states. The relation between these states and the “classical” trajectories is investigated, and we present numerical explorations of some semiclassical quantities.     

Generation of quantum switch and nonlocal fields with an external field in a high quality dispersive cavity

We present a scheme to prepare an optical “quantum switch”, a superposition of “open” and “closed” states. The scheme is based on the interaction of an Λ-type three-level atom with a single-mode of quantized cavity field and an external classical driving field, in the regime where the atom and fields are highly detuned. We show how this interaction can be used to generate coherent states of the cavity field in contrast to the usual method used in microwave cavity QED of injecting a coherent state into a cavity. A combination of switches could be used to prepare a quantum superposition of coherent field states located simultaneously in two cavities. Compared with previous proposals, our scheme is simplified due to economizes the Ramsey zone and the time required for the state generation is short.     

Saturation field direction dependence of domain structures in NiFe elements

The domain structures in NiFe elements were studied by magnetic force microscopy measurement and micromagnetic modeling. The remanent states in the elements were dependent on the direction of the saturation field. The “S” and “U” states were observed at remanence by applying the saturation field at different directions. The “S” and “U” states are metastable: magnetic force microscopy tip field-induced switching from the “S” and “U” states to the flux closure configuration was observed.     

Gauge invariance and spontaneous symmetry breaking in two-gap superconductors

The gauge symmetry of the Ginzburg–Landau theory for two-gap superconductors is analyzed in this letter. We argue that the existence of two different phases, associated with the two independent scalar Higgs fields, explicitly breaks the gauge symmetry of the Ginzburg–Landau Hamiltonian, unless a new additional vector field is included. Furthermore, the interference term, or Josephson coupling, holding a direct dependence with the phase difference, also explicitly breaks down the gauge symmetry. We show that a solution for the problem is achieved by adding an additional kinetic coupling term between the two vector fields, which generates the desired terms through a spontaneous symmetry breaking mechanism. Finally, the electrodynamics of the system is also presented in terms of the supercurrents inside the superconducting region.     

A visualization of the SU(2) vacuum on the lattice

Configurations of pure SU(2) gauge field theory on lattice are transformed to Landau gauge. After Fourier transformation, large momentum amplitudes are suppressed (filtered) by a variable amount, and the configurations are transformed back to x-space. Spectacular peaks in electric and magnetic field strengths are found, which share many properties with either almost pointlike instantons or with extended anti-instantons. The environment around those peaks are visualized with respect to the action, to the topological charge density, to the gauge fields and to electric and magnetic field strengths. The density of the peaks is of order 1 fm^–4, and it scales according to the string tension under a variation of the coupling constant. The evolution of the peaks under the amount of Fourier filtering is visualy compared to the evolution under cooling, and the gauge dependence of the peaks is discussed. Advantages and shortcomings of this method are discussed, with emphasis on possible strong distortions of the action and topological charge density, which become gauge dependent. Finally, I compare the character of the SU(2)-configurations to those of noncompact abelian theory.     

Density of states of random Schrödinger operators with a uniform magnetic field

We consider the density of states of Schrödinger operators with a uniform magnetic field and a random potential with a Gaussian distribution. We show that the restriction to the states of the first Landau level is equivalent to a scaling limit where one looks at the density of states near to the energy of the first Landau level and simultaneously lets the strength of the coupling to the random potential go to zero. We also consider a different limit where we look at the suitably normalised density of states near to the energy of the first Landau level when the intensity of the magnetic field goes to infinity.     

On higher derivatives in 3D gravity and higher-spin gauge theories

The general second-order massive field equations for arbitrary positive integer spin in three spacetime dimensions, and their “self-dual” limit to first-order equations, are shown to be equivalent to gauge-invariant higher-derivative field equations. We recover most known equivalences for spins 1 and 2, and find some new ones. In particular, we find a non-unitary massive 3D gravity theory with a 5th order term obtained by contraction of the Ricci and Cotton tensors; this term is part of an N=2 super-invariant that includes the “extended Chern-Simons” term of 3D electrodynamics. We also find a new unitary 6th order gauge theory for “self-dual” spin 3.     

Relatively heavy Higgs boson in more generic gauge mediation

We discuss gauge mediation models where the doublet messengers and Higgs doublets are allowed to mix through a “charged” coupling. The charged coupling replaces messenger parity as a means of suppressing flavor changing neutral currents without introducing any unwanted CP violation. As a result of this mixing between the Higgs doublets and the messengers, relatively large A-terms are generated at the messenger scale. These large A-terms produce a distinct weak scale mass spectrum. Particularly, we show that the lightest Higgs boson mass is enhanced and can be as heavy as 125 GeV for a gluino mass as light as 2 TeV. We also show that the stops are heavier than that predicted by conventional gauge mediation models. It is also shown that these models have a peculiar slepton mass spectrum.     

Non-Conservative Gravitational Equations

We propose a theory of gravity based on the interaction of the gauge field representing gravitation with a suitable vector substratum (physical vacuum). To build up the new theory, we exploit the formalism of the Symbolic Gauge Theory, an application to gauge theories of the General System Logic Theory, which results from the fusion of three mathematical structures, the logical theory of systems, the categorial algebra and the Lie algebra. The coupling of gravity to the substratum implies the nonconservation of the energy-momentum tensor. The derivative coupling term is approximated to the first order, and a Schwarzschild-like solution of the corresponding nonconservative gravitational equations is obtained. It is shown that, in this approximation, the main effect of the new theory is to introduce an extra-mass term in the standard Schwarzschild metric. The application of such a result to perihelion shifts and light deflection yields results comparable to those obtained in General Relativity. Gravitational-wave solutions of the new equations are derived in the weak field approximation. It is shown that our nonconservative theory of gravity implies a cosmological model with a locally varying, non-zero cosmological constant.     

Spinor fields in non-abelian Klein-Kaluza theories

We introduce a dimensional reduction procedure for a spinor field and a generalization of the minimal coupling scheme. We get an electric dipole moment of fermions of value 10^–31 cm and PC breaking for a gauge groupG with odd parameters. Reflection in higher (additional) dimensions are proposed as a conjugation of color charges connected with Yang-Mills fields. Our approach cancels Planck's mass terms in the Dirac equation.     

Spin-charge gauge compositeness of electron in HTS: Hints from metal-insulator crossover and entropy behavior

We show that the coexistence of Fermi arcs and metal-insulator crossover of the in-plane resistivity can give a hint of a peculiar “gauge compositeness” of the electron in hole-doped high T_c cuprates and a similar hint also comes from the negative intercept at T=0 of the electronic entropy extrapolated from moderate temperatures in the “pseudogap phase”. An implementation of this “compositeness” within the spin-charge gauge approach is outlined and is employed to discuss the above phenomena.     

A magnetic-monopole-type solution in the Poincaré gauge field theory of gravity

In a microscopical theory of gravity the coupling of internal gauge degrees of freedom to those of space-time are studied. A magnetic-monopole-type solution for the coupledSO(3) Yang-Mills-Higgs system in a space-time with curvature and torsion is derived. The coupling constant of the Lorentz gauge bosons can be related directly to the (constant) Higgs field and to the cosmological constant which is induced by the quadratic curvature terms in the Lagrangian. This reveals a new interpretation of the parameters entering the general Lagrangian density of the Poincaré gauge field theory (PG).     

On the nature of the photoproton spectra

Two classes of the proton channels of dipole LAS in the even-even nuclei have been studied: the decay into the “one hole” and “two hole-one particle” states of the residual nucleus. The photoproton spectra for ¹¹⁴Sn and ¹²⁴Sn have been calculated and compared with experiment.     

Role of dipole-dipole interactions in half-field quantum transitions in magnetic nanoparticles

In order to better understand the origin of “forbidden” quantum transitions observed in superparamagnetic nanoparticles at low magnetic fields, electron magnetic resonance (EMR) studies have been performed at room temperature on iron oxide nanoparticles assembled inside parallel nanosized channels penetrating the anodic alumina membrane. The positions of both the main resonance and “forbidden” (2Q) transitions observed at the half-field demonstrate the characteristic angular dependence with the line shifts proportional to 3cos²θ−1, where θ is the angle between the channel axis and external magnetic field B. This result can be attributed to the inter-particle dipole-dipole interactions within elongated aggregates inside the channels. The angular dependence of the 2Q intensity is found to be proportional to sin²θcos²θ, that is consistent with the predictions of quantum-mechanical calculations with the account for the mixing of states by non-secular inter-particle dipole-dipole interactions. Good agreement is obtained between different kinds of measurements (magnetization curves, line shifts and 2Q intensity), pointing to possibility of the quantum approach to the magnetization dynamics of superparamagnetic objects.     

Asymptotically de Sitter and anti-de Sitter black holes with confining electric potential

We study gravity interacting with a special kind of QCD-inspired nonlinear gauge field system which earlier was shown to yield confinement-type effective potential (the “Cornell potential”) between charged fermions (“quarks”) in flat space-time. We find new static spherically symmetric solutions generalizing the usual Reissner-Nordström-de Sitter and Reissner-Nordström-anti-de Sitter black holes with the following additional properties: (i) appearance of a constant radial electric field (in addition to the Coulomb one); (ii) novel mechanism of dynamical generation of cosmological constant through the non-Maxwell gauge field dynamics; (iii) appearance of confining-type effective potential in charged test particle dynamics in the above black hole backgrounds.     

Effective metrics in the non-minimal Einstein-Yang-Mills-Higgs theory

We formulate a self-consistent non-minimal five-parameter Einstein-Yang-Mills-Higgs (EYMH) model and analyse it in terms of effective (associated, color and color-acoustic) metrics. We use a formalism of constitutive tensors in order to reformulate master equations for the gauge, scalar and gravitational fields and reconstruct in the algebraic manner the so-called associated metrics for the Yang-Mills field. Using WKB-approximation we find color metrics for the Yang-Mills field and color-acoustic metric for the Higgs field in the framework of five-parameter EYMH model. Based on explicit representation of these effective metrics for the EYMH system with uniaxial symmetry, we consider cosmological applications for Bianchi-I, FLRW and de Sitter models. We focus on the analysis of the obtained expressions for velocities of propagation of longitudinal and transversal color and color-acoustic waves in a (quasi)vacuum interacting with curvature; we show that curvature coupling results in time variations of these velocities. We show, that the effective metrics can be regular or can possess singularities depending on the choice of the parameters of non-minimal coupling in the cosmological models under discussion. We consider a physical interpretation of such singularities in terms of phase velocities of color and color-acoustic waves, using the terms “wave stopping” and “trapped surface”.