Familon emissivity of dense e − e + plasma in an external magnetic field

Emission of a familon due to the processes e ^? → e ^?+φ and e ^? → μ ^?+φ by dense magnetized plasma is analyzed as a possible mechanism of energy and momentum losses by astrophysical objects. The field-induced effective familon-photon coupling in the familon-emission process is taken into account. The contribution of these processes to the familon emissivity of a magnetized plasma in a supernova explosion is calculated. It is shown that there is asymmetry of familon emission in the process e ^? → μ ^?+φ.     

Energy and momentum losses of a magnetized plasma via familon emission

Familon emission from a dense magnetized plasma in the processes e^? → e^?φ and e^? → μ^?φ is investigated. The contribution of these processes to the energy losses of a supernova remnant is calculated. It is shown that, at a late stage of the cooling of a supernova remnant, the energy loss of a plasma via familon emission may become commensurate with the loss via neutrino emission. It is found that, because of asymmetry of familon emission in the process e^? → gm^?φ, there arises a force acting on the plasma.     

Transition amplitudes and probabilities for the Weinberg-Salam model

Transition probabilities for the processes vv?vv, vv?, $\text{vv}$?$\text{vv}$, and spin-dependent transition amplitudes for the processes ve?ve, vē?vē, v?e?v?e, $\text{ve}$?$\text{ve}$ and vv??eē are calculated in lowest order for the Weinberg-Salam model.     

Familon → photon transition in a magnetized plasma

The external-magnetic-field-induced interaction of a pseudoscalar particle with a photon is investigated in e^?e⁺ plasma. The familon arising upon the breakdown of a horizontal symmetry between fermion generations is considered for a pseudoscalar particle. The expressions for the plasma and the field contribution to the effective familon-photon coupling are derived in the limit of strongly magnetized plasma and the limit where the plasma being considered occurs in a relatively weak magnetic field.     

Photon processes in a strongly magnetized plasma

The photon-scattering process γe ^± → γe ^± is considered in strongly magnetized matter at arbitrary values of temperature and an arbitrary chemical potential. Simple expressions for the absorption coefficients in a strongly magnetized plasma are obtained in two limiting cases, that of a rarefied chargesymmetric plasma and that of a degenerate plasma. Astrophysical applications of the results obtained here are discussed.     

Efficiency of electron-positron pair production by neutrino flux from accretion disk of a Kerr black hole

Dominant processes of neutrino production and neutrino-induced e ⁺ e ^?-pair production are examined in the model of a disk hyperaccreting onto a Kerr black hole. The efficiency of plasma production is analytically estimated for both the presence and the absence of a strong magnetic field. It is shown that the efficiency of plasma production by a neutrino flux from the disk in this model is no more than several tenths of percent and, therefore, cannot account for the origin of cosmological gamma-ray bursts.     

Axially magnetized electron–positron and electron plasma competition on the self focusing of intense laser beam

The spot-size evolution of circularly polarized intense laser beam propagating through the axially magnetized electron–positron (EP) and electron plasmas is discussed, in mildly relativistic and weakly non-linear (a² ? 1) regime. The non-linear current density source terms are obtained by making used of the perturbative technique. The variational principle approach method is applied to the solution of the non-linear Schrodinger wave equation. It is shown that the laser beam spot size decreases for the left and increases for the right handed polarized beams with increasing the external magnetic field, owing to the beam passages inside the electron plasma. Furthermore, it is revealed that the self focusing property strongly enhanced in the EP plasma in comparison to the electron plasma. Moreover, self focusing of linearly polarized laser beam is investigated for EP plasma by superposition of the right and left circularly polarized beams.     

Fluctuations in the relativistic quantum plasma

The fluctuations of various parameters of the relativistic quantum plasma are studied with the use of the covariant Wigner function techniques. The fluctuations of the covariant Wigner function of the ideal Fermi gas at thermal equilibrium are calculated. The result is a function of the one particle Wigner function and the anticommutator of the Dirac fields only. As a consequence second order correlation functions of the four-current and the momentum-energy tensor are obtained and analyzed. On the basis of the fluctuation-dissipation theorem, the polarization tensors at first order in e² of the magnetized and the non-magnetized electron gas are derived from the four-current fluctuations of the ideal plasma. Expressions are given for the magnetized vacuum polarization in two representations, integral and discrete sums over Landau levels, for arbitrary values of the photon four-momentum. The dispersion relations of the magnetized gas are studied in the limit of low frequencies and wavenumbers. It is shown that owing to relativistic quantum effects, the characteristic frequencies of the plasma modes (plasma and Larmor frequencies) split into effective transverse and longitudinal frequencies. The existence of an acoustic mode (zero sound) for the one-component plasma is also shown.     

New acceleration mechanism of electrons by an electromagnetic wave in a weakly magnetized plasma

Acceleration of electrons by an electromagnetic wave has been observed in a weakly magnetized (ω_ce/ω₀ ? 10^?2) inhomogeneous plasma. This acceleration is interpreted as a V_p × B₀ acceleration, which is a new concept for heating or accelerating electrons very efficiently to high energy.     

Neutrino Self-Energy and Index of Refraction in Strong Magnetic Field: A New Approach

The Ritus E_p eigenfunction method is extended to the case of spin-1 charged particles in a constant electromagnetic field and used to calculate the one-loop neutrino self-energy in the presence of a strong magnetic field. From the obtained self-energy, the neutrino dispersion relation and index of refraction in the magnetized vacuum are determined within the field range m²_e?eB?M²_W. The propagation of neutrinos in the magnetized vacuum is anisotropic due to the dependence of the index of refraction on the angle between the directions of the neutrino momentum and the external field. Possible cosmological implications of the results are discussed.     

Modulated electron spectrum of the light scattered by a magnetized arc plasma

Measuring the spectrum of laser light scattered by a magnetized arc plasma (n _e =1.2 × 10¹⁶ cm^?3,T _e =3.2 eV, α=0.6,B _z =120 kG) we observe deviations from the normal thermal spectrum. The observed modulation is most probably due to the influence of the magnetic field. Two other less likely possibilities (enhanced electron oscillations or the existence of an additional colder electron component) are discussed.     

A change in the conductivity of sodium-helium plasma interacting with polarization-modulated laser radiation tuned to sodium D 1 line

A change in the conductivity of a sodium-helium plasma interacting with laser radiation tuned to the sodium 3² S _1/2?3² P _1/2 transition and having sign-changing polarization is experimentally observed. It is shown that this effect is caused by the processes of Penning ionization, spin exchange, and optical orientation of atoms in a gas-discharge plasma.     

Amplitude modulation and demodulation of an electromagnetic wave in magnetised acousto-optic diffusive semiconductor plasmas: Hot carrier effects

In communication processes, amplitude modulation is very helpful to save power using a single band transmission. Using the hydrodynamical model of semiconductor plasma analytical investigations are made for the amplitude modulation as well as demodulation of an electromagnetic wave incorporating carrier heating (CH) effects in acousto-optic magnetised semiconductor plasma. The CH effects add new dimensions in the present analysis. Analysis are made under different wave number regions over a wide range of cyclotron frequencies. It is found that incorporation of CH effects modifies the amplitude modulation and demodulation processes effectively. Numerical estimations are made for III–V semiconductor crystal irradiated by pump wave of frequency 1.6×10¹³ s^?1. Complete absorption of the waves takes place in all the possible wavelength regimes when the cyclotron frequency ω_c becomes nearly equal to ω₀, the pump frequency on neglecting the collision term in modulation/ demodulation indices.     

Spin damping correction to electrostatic modes in kinetic plasma theory

The effect of spin of particles is studied using a semi-classical kinetic theory for a magnetized plasma. No other quantum effects are included. We focus in the simple damping effects for the electrostatic wave modes. Besides Landau damping, we show that spin produces two new different effects of damping or instability which are proportional to ?. These corrections depend on the electromagnetic part of the wave that is coupled with the spin vector.     

Parametric transformation of the amplitude and frequency of a whistler wave in a magnetoactive plasma

The results of experiments studying the propagation of a high-frequency whistler wave in a magnetized plasma duct in the presence of an intense low-frequency wave also related to the whistler frequency range are reported. Amplitude-frequency modulation of the high-frequency whistler wave trapped in the duct was observed. A deep amplitude modulation of the signal that can lead to its splitting into separate wave packets is observed. It is shown that an increase in the wave propagation path leads to a broadening of the wave frequency spectrum and to a shift of the signal spectrum predominantly toward the red side. The transformation of the frequency of the high-frequency wave is related with the time-dependent perturbation of the external magnetic field by the field of the low-frequency whistler wave (the relative perturbation of the magnetic field δB/B≤5×10^?2).     

磁化等离子体的纵向电阻率

从动力论方程出发,推导并讨论了磁化与非磁化等离子体的纵向电阻率。结果是:(1)各向同性磁化等离子体的电阻率约为非磁化者的1.5倍;(2)对各向异性的等离子体而言,磁化后的电阻率约与T_e⊥T_e‖^-5/2成正比,但非磁化时的电阻率则与T_e⊥^-1T_e‖^-1/2成正比。以上的差异主要是来自外磁场对电子运动轨迹的作用。同时本文亦论述了在讨论经典电阻率时,静态屏蔽作用是主要的,而动力屏蔽对电阻率的影响是可以忽略不计的。 关键词：     

Initial-state radiation at LEP energies and the corrections to Higgs boson production

It is shown that for e⁺e^? scattering processes described by the exchange of one photon or vector boson the O(α) radiative corrections to the initial state completely factorize the lowest-order cross section. This factorization holds for both hard and soft (or virtual) photons. We present a formalism for applying these radiative corrections in a process-independent way, and described the corresponding computer program. As an application we study the initial-state radiative corrections to the Higgs production processes e⁺e^? → μ⁺μ^?H and e⁺e^? → e⁺e^?H.     

Nonlinear plasma spectroscopy of the hydrogen balmer-α line

The plasma line broadening of H_α fine-structure lines is investigated with Doppler-free saturation and polarization spectroscopy in He-H gas and are discharges at plasma densities of 10⁸ cm^?3 <N?1.4×10¹⁴ cm^?3. With a single-mode laser, the shift and broadening of four resolved H_α fs lines are measured in a low pressure discharge forN<10¹¹ cm^?3. With an intense, broadband multi-mode laser the plasma effects of H_α are investigated up toN=1.4×10¹⁴ cm^?3 in a hollow cathode are. Calculations in the classical phase shift and impact approximations can explain the experimental data and peculiarities of the low-density plasma effects and show that the ions are the dominant perturbers. Ion dynamical effects, perturber mass and temperature dependence, are observed and interpreted. Applications of the nonlinear techniques to other H and D lines, other atoms, and for H and D plasma diagnostics are discussed.     

Charm production by weak neutral currents

We discuss quantitatively the production of charm in $\text{v}\text{N and}\text{v}\text{N}$ neutral current interactions, and the anomalous lepton events that follow from semi-leptonic charm decay. Diagonal neutral currents, in the Weinberg-Salam model and similar models, predict associated charm production with small cross sections: e.g. $\text{σ(v}\text{N}\text{→ vcc}{}^{\mathrm{?}}\text{X}\text{)/σ(v}\text{N}\text{→ μ}{}^{\mathrm{?}}\text{X}\text{) ? 10}{}^{\mathrm{?2}}$ at high energy. The meagre data on vN → ve⁺X are consistent with a rate of this order. Non-diagonal neutral currents, if present, could give larger cross sections via valence p → c transitions. It should be possible to distinguish diagonal from non-diagonal contributions by their x- or u-dependences, where u = x(1 ? y). We calculate the expected energy distributions of the leptons in characteristic vN → v?⁺X and vN → v?⁺?^?X charm decay events using simple models, and discuss some practical problems in neutral current measurements.     

Optical and electrical properties of amorphous arsenic

Amorphous arsenic prepared by plasma decomposition of arsine has been characterized using field-effect conductance, thermopower, optical absorption, and photoconductivity measurements. It is found that the Fermi level is located in a density of states ～ 10¹⁷ cm^?3 eV^?1 approximately in the center of the forbidden gap, that conduction occurs via electrons in extended states in the conduction band, and that the optical and photoelectrical properties are very similar to those of bulk a-As. It is concluded that a model involving a negative correlation energy for localized states is inappropriate for this material.