Electromagnetic processes in a χEFT framework

Recently,we have derived a two–nucleon potential and consistent nuclear electromagnetic currents in chiral effective field theory with pions and nucleons as explicit degrees of freedom.The calculation of the currents has been carried out to include N 3 LO corrections,consisting of two–pion exchange and contact contributions.The latter involve unknown low-energy constants （LECs）,some of which have been fixed by fitting the np Sand P-wave phase shifts up to 100 MeV lab energies.The remaining LECs entering the current operator are determined so as to reproduce the experimental deuteron and trinucleon magnetic moments,as well as the np cross section.This electromagnetic current operator is utilized to study the nd and n 3 He radiative captures at thermal neutron energies.Here we discuss our results stressing on the important role played by the LECs in reproducing the experimental data.     

Cerenkov third-harmonic generation via cascaded χ(2) processes in a periodic-poled LiTaO₃ waveguide

We report a type of quasi-phase-matched (QPM) Cerenkov third-harmonic generation (CTHG) in a periodic-poled LiTaO? waveguide. The CTHG results from a guided-to-guided second-harmonic generation cascaded with a guided-to-radiated sum-frequency generation (SFG) in the waveguide. In the guided-to-radiated SFG process, nonlinear interactions with participating and nonparticipating reciprocal vectors would lead to different CTHG radiations. In addition, the power and temperature detuning characters of QPM CTHG were studied. Theoretical predictions were in good agreement with experimental results.     

Electronic Wave Packet in a Quantized Electromagnetic Field

We study a non-stationary electronic wave packet in a quantized electromagnetic field.Generally,the electron and field become entangled as the electronic wave packet evolves.Here we find that,when the initial photon state is a coherent one,the wavefunction of the system can be factorized if we neglect the transferred photon number.In this case,the quantized-field calculation is equivalent to the semi-classical calculation.     

Relativistic Electromagnetic Solitary Wave in a Cylindrical Magnetized Plasma

In the presence of an applied static and uniform magnetic field, a cylindrical Kadomtsev-Petviashivili equation is derived for a relativistic electromagnetic solitary wave propagating in collisionless plasma consisting electrons, positrons, and ions in the case of weak relativistic limit. This equation is solved in a stationary frame to obtain explicit expression for the velocity, amplitude and width of solitons. The amplitude of the solitary wave has a maximum value at a critical αc of the ratio of the ion equilibrium density to the electron one, and it increases as the applied magnetic field becomes larger.     

Scheme for Generating a χ-Type Four-Atom Entangled State in Cavity QED

We propose a scheme for generating a χ-type four-atom entangled state in cavity QED. In the present scheme, the atoms interact simultaneously with a highly detuned cavity mode with the assistance of a strong classical field. The scheme is insensitive to the cavity decay and the thermal field, which is of importance from the experimental point of view.     

Electromagnetic transition properties of→Nγ in a hypercentral scheme

The electromagnetic transition properties of the decuplet to octet baryon (→ Nγ) is studied within the framework of a hypercentral quark model.The confinement potential is assumed as a hypercentral coloumb plus linear potential.The transition magnetic moment and transition amplitude f M 1 for the → Nγ are in agreement with other theoretical predictions.The present result of the radiative decay width is found to be in excellent agreement with the experimental values reported by the particle data group over other theoretical model predictions.     

Electromagnetic N-Δ transition form factors in a covariant quark-diquark model

The electromagnetic N-Δ transition form factors are calculated in the framework of a formally covariant constituent diquark model. As a spin- $tfrac {3}{2}$ particle the Δ is assumed to be a bound state of a quark and an axial-vector diquark. The wave function is obtained from a diquark-quark Salpeter equation with an instantaneous quark exchange potential. The three transition form factors are calculated for momentum transfers squared from the pseudothreshold (M_Δ ?M _N )² up to ?2 (GeV/c)². The magnetic form factor is in qualitative agreement with experiment. We find very interesting results for the ratios E2/M1 and C2/M1.     

Continuous Quantum Nondemolition Measurements of a Particle in Electromagnetic and Gravitational Fields

The detection of a particle in electromagnetic plus gravitational fields is investigated. We obtain a set of quantum nondemolition variables. The continuous measurements of these nondemolition parameters are analyzed in the framework of restricted path integral formalism. We manipulate the corresponding propagators, and deduce the probabilities associated with the possible measurement outputs.     

Electromagnetic transition properties of Δ→Nγ in a hypercentral scheme

The electromagnetic transition properties of the decuplet to octet baryon (Δ→Nγ) is studied within the framework of a hypercentral quark model. The confinement potential is assumed as a hypercentral coloumb plus linear potential. The transition magnetic moment and transition amplitude f_M1 for the Δ→Nγ are in agreement with other theoretical predictions. The present result of the radiative decay width is found to be in excellent agreement with the experimental values reported by the particle data group over other theoretical model predictions.     

Electromagnetic Quantities in Black Hole Magnetosphere

Some electromagnetic quantities in the black hole (BH) magnetosphere are discussed by considering the coexistence of the Blandford-Znajek process and the magnetic coupling process. These quantities are (i) flux of electromagnetic energy and angular momentum transferred between the BH and the disc, (ii) poloidal currents flowing on the     

η-Photoproduction in a gauge-invariant chiral unitary framework

We analyze photoproduction of η mesons off the proton in a gauge-invariant chiral unitary framework. The interaction kernel for meson-baryon scattering is derived from the leading order chiral effective Lagrangian and iterated in a Bethe-Salpeter equation. The recent precise threshold data from the Crystal Ball at MAMI can be described rather well and the complex pole corresponding to the S₁₁(1535) is extracted. An extension of the kernel is also discussed.     

Can a Wormhole Generate Electromagnetic Field?

We have considered the possibility of a rotating wormhole surrounded by a cloud of charged particles. Due to slow rotation of the wormhole, the charged particles are dragged, thereby producing an electromagnetic field. We have determined the strength of this electromagnetic field and the corresponding flux of radiation.     

Magnetic flux inversion in charged BPS vortices in a Lorentz-violating Maxwell–Higgs framework

We demonstrate for the first time the existence of electrically charged BPS vortices in a Maxwell–Higgs model supplemented with a parity-odd Lorentz-violating (LV) structure belonging to the CPT-even gauge sector of the standard model extension and a fourth order potential (in the absence of the Chern–Simons term). The modified first order BPS equations provide charged vortex configurations endowed with some interesting features: localized and controllable spatial thickness, integer flux quantization, electric field inversion and localized magnetic flux reversion. This model could possibly be applied on condensed matter systems which support charged vortices carrying integer quantized magnetic flux, endowed with localized flipping of the magnetic flux.     

Generation of a χ-type four-atom entangled state

This paper proposes a scheme to generate a new χ-type four-atom entangled state for the first time by using linear optics elements, four one-sided cavities (one three-level atom) and a conventional photon detector. The linear optical elements and conventional photon detector are simple and accessible in experiments, which makes the scheme more feasible with current technology. In addition, the state |χ⁰⁰₃₂₁₄ with probability 1 can be generated as long as there is no photon loss.     

Brownian Motion of a Charged Particle in Electromagnetic Fluctuations at Finite Temperature

The fluctuation-dissipation theorem is a central theorem in nonequilibrium statistical mechanics by which the evolution of velocity fluctuations of the Brownian particle under a fluctuating environment is intimately related to its dissipative behavior. This can be illuminated in particular by an example of Brownian motion in an ohmic environment where the dissipative effect can be accounted for by the first-order time derivative of the position. Here we explore the dynamics of the Brownian particle coupled to a supraohmic environment by considering the motion of a charged particle interacting with the electromagnetic fluctuations at finite temperature. We also derive particle’s equation of motion, the Langevin equation, by minimizing the corresponding stochastic effective action, which is obtained with the method of Feynman-Vernon influence functional. The fluctuation-dissipation theorem is established from first principles. The backreaction on the charge is known in terms of electromagnetic self-force given by a third-order time derivative of the position, leading to the supraohmic dynamics. This self-force can be argued to be insignificant throughout the evolution when the charge barely moves. The stochastic force arising from the supraohmic environment is found to have both positive and negative correlations, and it drives the charge into a fluctuating motion. Although positive force correlations give rise to the growth of the velocity dispersion initially, its growth slows down when correlation turns negative, and finally halts, thus leading to the saturation of the velocity dispersion. The saturation mechanism in a supraohmic environment is found to be distinctly different from that in an ohmic environment. The comparison is discussed.     

Elementary Andreev processes in a driven superconductor–normal metal contact

We investigate the full counting statistics of a voltage-driven normal metal(N)–superconductor(S) contact. In the low-bias regime below the superconducting gap, the NS contact can be mapped onto a purely normal contact, albeit with doubled voltage and counting fields. Hence in this regime the transport characteristics can be obtained by the corresponding substitution of the normal metal results. The elementary processes are single Andreev transfers and electron- and hole-like Andreev transfers. Considering Lorentzian voltage pulses we find an optimal quantization for half-integer Levitons.     

Excitation of Electromagnetic Waves by an Electron Ring Beam in a Magnetized Plasma Waveguide

We study the resonant interactions between an electron ring beam and plasma waveguide modes,This is motivated by the research of radio emission in low solar corona.We consider a density-depleted duct(above an active region near a flare site)that may be treated as a magnetized plasma waveguide.The electromagnetic waves excited in the wveguide are classified into the so-called E-type and B-type waves.The results show that there are two unstable modes of B-type waves propagating parallel and anti-parallel to the direction of the electron beam.The effect of the finite radius and boundary conditions of the waveguide on the excitation of the electron beam.The effect of the finite radius and oundary conditions of the waveguide on the excitation of waveguide modes is important.For a given B-type mode,the smaller the radius R,the larger the temporal and spatial amplification important.For a given B-type mode.the smaller the radius R ,the larger the temporal and spatial amplification rate,we suggest that these excited waveguide modes could be one of the processes respondsible for the observed solar radio emission.     

Detecting a single atom in a cavity using the χ(2) nonlinear medium

We propose a protocol for detecting a single atom in a cavity with the help of the χ⁽²⁾ nonlinear medium. When the χ⁽²⁾ nonlinear medium is driven by an external laser field, the cavity mode will be squeezed, and thus one can obtain an exponentially enhanced light-matter coupling. Such a strong coupling between the atom and the cavity field can significantly change the output photon flux, the quantum fluctuations, the quantum statistical property, and the photon number distributions of the cavity field. This provides practical strategies to determine the presence or absence of an atom in a cavity. The proposed protocol exhibits some advantages, such as controllable squeezing strength and exponential increase of atom-cavity coupling strength, which make the experimental phenomenon more obvious. We hope that this protocol can supplement the existing intracavity single-atom detection protocols and provide a promise for quantum sensing in different quantum systems.     

The Low-Energy p–d System in Pionless EFT

We summarize results presented at the 5th Asian Pacific Conference on Few Body Problems in Physics, which was held in Seoul in August 2011. We calculate low-energy quartet and doublet channel proton–deuteron scattering in the framework of pionless effective field theory. We obtain good agreement with the available phase shift analyses. Moreover, we calculate the Coulomb contribution to the ³He–³H binding energy difference in first order perturbation theory.     

Solution of Electromagnetic Wave in Time-Varying Media in Two-Dimensional Space

The analytical solution of gradual change media in two-dimensional free space is studied. Using separation of variables, the solution of electromagnetic wave in time-varying media, which is an exponential function of time, is derived in two-dimensional space. The rationality of the solution is verified indirectly. According to the solution, the figures of the wave are depicted. Based on these figures, the character of the wave in time-varying media is obtained, which shows frequency shift and changes of phase velocity and amplitude.