Apparent anomalous behavior of the power spectrum of 1/f noise and its explanation

The explanation is given for the apparent anomalous behavior of the power spectrum of 1/f noise as if it corresponded to the total infinite power of noise sources. Physical mechanisms eliminating the apparent anomalies are described. With these mechanisms, the finite and integrable 1/f-noise power spectra fitting the known physical concepts of noise processes are obtained in the low-and high-frequency limits.     

The anomalous chiral Schwinger model and its quantization

We solve the anomalous chiral Schwinger model in the hamiltonian formulation implementing the Faddeev proposal. We diagonalize the hamiltonian by functional techniques and construct the eigenfunctionals of the quantized system. The spectrum is non Lorentz invariant since the Poincarè algebra is not closed. We point out that, relinquishing the Faddeev condition, there would be an infinite degeneration of the hamiltonian. Among the degenerate 1-particle eigenfunctionals it is possible to find a state with relativistic spectrum. We also examine the meaning of a non local modification of the hamiltonian which restores Lorentz invariance.     

PAMELA and dark matter

Assuming that the positron excess in PAMELA satellite data is a consequence of annihilations of cold dark matter, we consider from a model-independent perspective if the data show a preference for the spin of dark matter, and find that they do not. We then perform a general analysis of annihilations into two-body states to determine what weighted combination of channels best describes the data.     

一价原子有精细结构时的塞曼效应

利和微扰理论导出了一价原子在静磁场中有精细结构时塞曼效应的一般表达式。     

Crossover behavior of the anomalous Hall effect and anomalous nernst effect in itinerant ferromagnets

The anomalous Hall effect (AHE) and anomalous Nernst effect (ANE) are experimentally investigated in a variety of ferromagnetic metals including pure transition metals, oxides, and chalcogenides, whose resistivities range over 5 orders of magnitude. For these ferromagnets, the transverse conductivity sigma{xy} versus the longitudinal conductivity sigma{xx} shows a crossover behavior with three distinct regimes in accordance qualitatively with a recent unified theory of the intrinsic and extrinsic AHE. We also found that the transverse Peltier coefficient alpha{xy} for the ANE obeys the Mott rule. These results offer a coherent and semiquantitative understanding of the AHE and ANE to an issue of controversy for many decades.     

The effect of time-delay on anomalous phase synchronization

Anomalous phase synchronization in nonidentical interacting oscillators is manifest as the increase of frequency disorder prior to synchronization. We show that this effect can be enhanced when a time-delay is included in the coupling. In systems of limit-cycle and chaotic oscillators we find that the regions of phase disorder and phase synchronization can be interwoven in the parameter space such that as a function of coupling or time-delay the system shows transitions from phase ordering to disorder and back.     

Non-Hermitian anomalous skin effect

A non-Hermitian topological insulator is fundamentally different from conventional topological insulators. The non-Hermitian skin effect arises in a nonreciprocal tight binding lattice with open edges. In this case, not only topological states but also bulk states are localized around the edges of the nonreciprocal system. We discuss that controllable switching from topological edge states into topological extended states in a chiral symmetric non-Hermitian system is possible. We show that the skin depth decreases with non-reciprocity for bulk states but increases with it for topological zero energy states.     

Interacting quantum wires: A possible explanation for the 0.7 anomalous conductance

We investigate an effective one-dimensional conducting channel considering both the contact umklapp and the Coulomb electron-electron interaction. We show that, at low electronic density, the proximity to the Wigner crystal reproduces the anomaly in conductance at 0.7G₀. The crucial ingredient of our theory is the fact that the gate voltage acts as a bias controlling the intensity of the umklapp term. At large gate voltages, the umklapp vanishes and we obtain a conducting quantum wire with a perfect conductance. At low gate voltages, the Wigner crystal is pinned by the umklapp term, giving rise to an insulating behavior with vanishing conductance. This crossover pattern has a transition point which can be identified with the anomalous conductance around 0.7G₀. This picture is obtained within the framework of a renormalization group calculation. The conductance static regime is achieved by taking first the limit of finite length and then the limit of zero frequency.     

An explanation of the anomalous temperature dependence of optical linewidths in glasses

Recently photochemical holeburning experiments have been carried out in organic glasses down to 0.4 K. Here we give a theoretical explanation of theT ^1.3-dependence of the holewidth. It is based on the strain field coupling between impurity molecules and two-level tunneling states leading to a kind of spectral diffusion of the optical excitation energy.     

From PAMELA to CDMS and back

We study implications of the recent results from the CDMS Collaboration on astrophysical probes of dark matter. By crossing symmetry an elastic scattering cross section with the nucleon implies annihilation of dark matter into hadrons inside the halo, resulting in an anti-proton flux that could be constrained by data from the PAMELA Collaboration if one includes a large boost factor necessary to explain the PAMELA excess in the positron fraction. As an illustration, we present a model-independent analysis for a fermionic dark matter and study the upper bound on the boost factor using the PAMELA anti-proton flux.     

The anomalous Hanle effect in semimagnetic semiconductor quantum wells

The behavior of the optical-orientation signal under resonant optical excitation of localized excitons in quantum wells with semimagnetic layers was studied both experimentally and theoretically. The most remarkable experimental observation made in this study is the increase in the degree of polarization of the quantum well radiation in the conditions in which the Hanle effect is observed. The behavior of magnetically induced circular luminescence polarization in a slightly tilted field (quasi-Voigt geometry) also appears unusual. Possible specific contributions to the optical exciton orientation in semimagnetic nanostructures are discussed. A theoretical model is proposed which, while being based on the well-known concepts of collective spin dynamics of magnetic ions in the exchange field of a photoexcited hole, takes into account fluctuations of the local magnetization. The calculations agree quantitatively with experiment for reasonable values of the parameters.     

The Kohn-Luttinger effect and anomalous pairing in new superconducting systems and graphene

We present a review of theoretical investigations into the Kohn-Luttinger nonphonon superconductivity mechanism in various 3D and 2D repulsive electron systems described by the Fermi-gas, Hubbard, and Shubin-Vonsovsky models. Phase diagrams of the superconducting state are considered, including regions of anomalous s-, p-, and d-wave pairing. The possibility of a strong increase in the superconducting transition temperature T _c even for a low electron density is demonstrated by analyzing the spin-polarized case or the two-band situation. The Kohn-Luttinger theory explains or predicts superconductivity in various materials such as heterostructures and semimetals, superlattices and dichalcogenides, high-T _c superconductors and heavy-fermion systems, layered organic superconductors, and ultracold Fermi gases in magnetic traps. This theory also describes the anomalous electron transport and peculiar polaron effects in the normal state of these systems. The theory can be useful for explaining the origin of superconductivity and orbital currents (chiral anomaly) in systems with the Dirac spectrum of electrons, including superfluid ³He-A, doped graphene, and topological superconductors.     

Double-action dark matter,PAMELA and ATIC

Motivated by a two-bump (or 1-peak plus 1-hump) structure in the ATIC data, we perform a statistical analysis fitting the PAMELA and ATIC data to a dark matter model, in which the dark matter particle can undergo both annihilation and decay. Using a chi-square analysis we show that both data can be simultaneously fitted better with such a double-action dark matter particle. We use an existing neutrino mass model in literature to illustrate the idea.     

PAMELA,FGST and sub-TeV dark matter

PAMELA's observation that the cosmic ray positron fraction increases rapidly with energy implies the presence of primary sources of energetic electron–positron pairs. Of particular interest is the possibility that dark matter annihilations in the halo of the Milky Way provide this anomalous flux of antimatter. The recent measurement of the cosmic ray electron spectrum by the Fermi Gamma Ray Space Telescope, however, can be used to constrain the nature of any such dark matter particle. In particular, it has been argued that in order to accommodate the observations of Fermi and provide the PAMELA positron excess, annihilating dark matter particles must be as massive as ∼1 TeV or heavier. In this Letter, we revisit Fermi's electron spectrum measurement within the context of annihilating dark matter, focusing on masses in the range of 100–1000 GeV, and considering effects such as variations in the astrophysical backgrounds from the presence of local cosmic ray accelerators, and the finite energy resolution of the Fermi Gamma Ray Space Telescope. When these factors are taken into account, we find that dark matter particles as light as ∼300 GeV can be capable of generating the positron fraction observed by PAMELA.     

Berry-phase effect in anomalous thermoelectric transport

We develop a theory of the Berry-phase effect in anomalous transport in ferromagnets driven by statistical forces such as the gradient of temperature or chemical potential. Here a charge Hall current arises from the Berry-phase correction to the orbital magnetization rather than from the anomalous velocity, which does not exist in the absence of a mechanical force. A finite-temperature formula for the orbital magnetization is derived, which enables us to provide an explicit expression for the off-diagonal thermoelectric conductivity, to establish the Mott relation between the anomalous Nernst and Hall effects, and to reaffirm the Onsager relations between reciprocal thermoelectric conductivities. A first-principles evaluation of our expression is carried out for the material CuCr(2)Se(4-x)Br(x), obtaining quantitative agreement with a recent experiment.     

Surface plasmons and the extreme anomalous skin effect

We have derived a simple formula for the dispersion relation of surface plasmons on metals in the extreme anomalous skin effect region. Comparisons of this theory with the usual local dielectric theory is made for Cu, Ag, Au, Sn, and Pb. The two theories can be more than two orders of magnitude different in their predictions of propagation lengths, depending on the temperature.