Search results for "electrodynamics"
showing 10 items of 820 documents
Meson Properties in Nuclear Medium
2003
In this paper, we report on the properties of meson resonances in the nuclear medium, in the scalar and vector sectors. First of all, the ρ meson is studied by looking at the pion-pion scattering amplitude in the vector-isovector channel, following a chiral unitary framework in free space and in the medium. The pious are modified in the medium by means of p-h and Δ-h excitations, and the p meson couples to these components as well as to N*(1520)-h excitations. Second, the Φ meson spectrum due to the kaon channel is obtained in terms of the Φ selfenergy provided by a chiral SU(3) dynamics model. The medium effects are considered in the properties of K and K mesons which are renormalized by S…
Instability of single-frequency operation in semilinear photorefractive coherent oscillators.
2002
The transition of the single-frequency oscillation of a semilinear photorefractive coherent oscillator for sufficiently large coupling strengths into two-frequency oscillation is predicted and is observed experimentally. The critical value of the coupling strength at which the bifurcation occurs is a function of pump intensity ratio and cavity losses. The supercritical bifurcation in the oscillation spectrum is analogous to the second-order phase transition.
Second-order optical phase transition in a semilinear photorefractive oscillator with two counterpropagating pump waves
2002
Soft-mode onset of coherent oscillation is revealed in a semilinear cavity with two counterpropagating pump waves. From the dynamics of the oscillation intensity and the dynamics of the grating decay with the feedback applied, critical behavior is detected: Both the characteristic time of oscillation onset and grating decay time go to infinity exactly at the threshold coupling strength. A conclusion is made about the similarity of this type of oscillator to the second-order phase transition.
Three dimensional hydrodynamics of ultrarelativistic heavy ion collisions
1988
We have utilized a 2+1 dimensional numerical code based on Flux Corrected Transport method to find a solution for 3+1 dimensional cylindrically symmetric hydrodynamic flow of hadronic matter which is assumed to be formed in extremely high energy heavy ion collisions. The hydrodynamics is supplemented with a decoupling calculation in order to produce measurable particle distributions. This numerical procedure is applied here to Landau type initial conditions which have been fixed using a simple geometrical picture for a central O+Pb collision at 200 GeV/nucleon. The bag equation of state for nonbaryonic matter is used to simulate the deconfinement phase transition to quark gluon plasma. The …
Electroweak baryogenesis at high bubble wall velocities
2020
It is widely believed that electroweak baryogenesis should be suppressed in strong phase transitions with fast-moving bubble walls, but this effect has never been quantitatively studied. We rederive fluid equations describing transport of particle asymmetries near the bubble wall without making the small-wall-velocity approximation. We show that the suppression of the baryon asymmetry is a smooth function of the wall speed and that there is no special behavior when crossing the sound speed barrier. Electroweak baryogenesis can thus be efficient also with strong detonations, generically associated with models with observably large gravitational waves. We also make a systematic and critical c…
Quantum chemical study of electron‐phonon interaction in crystals
2013
Study of the interaction of the electromagnetic radiation with nonlocal potentials and the electron-phonon interaction is motivated by its key role in non-classical phenomena in dielectrics and semiconductors. Actual in second quantization is decoupling of the undesirable mixture of electronic and phonon birth/annihilation operators and obtaining the effect of radiation in presence of the nonlocal potentials. Here we transform an arbitrary effective electron- phonon Hamiltonian in two matrices – the matrix of a new interaction Hamiltonian and the matrix of the transformation. For a particular effective Hamiltonian formulated in second quantization these two matrices outline a starting point…
Gravity and handedness of photons
2017
Vacuum fluctuations of quantum fields are altered in presence of a strong gravitational background, with important physical consequences. We argue that a non-trivial spacetime geometry can act as an optically active medium for quantum electromagnetic radiation, in such a way that the state of polarization of radiation changes in time, even in the absence of electromagnetic sources. This is a quantum effect, and is a consequence of an anomaly related to the classical invariance under electric-magnetic duality rotations in Maxwell theory.
Strong-field high-frequency approximation to the multiphoton ionization of hydrogen
1990
The strong-field multiphoton ionization of atoms is considered and a theoretical approach dealing nonperturbatively with the radiation field formulated. The general computational scheme is the conventional perturbation theory, but the intermediate states are dressed by the field. We present in detail a method to dress the continuum states and to study the dipole transitions within the continuum. In the high-frequency domain, the proposed procedure rapidly converges over a wide range of field intensity and offers an interesting framework for calculating ionization rates for arbitrary numbers of absorbed (above-threshold) photons and field polarization.
Efficient generation of N-photon binomial states and their use in quantum gates in cavity QED
2010
A high-fidelity scheme to generate N-photon generalized binomial states (NGBSs) in a single-mode high-Q cavity is proposed. A method to construct superpositions of exact orthogonal NGBSs is also provided. It is then shown that these states, for any value of N, may be used for a realization of a controlled-NOT gate, based on the dispersive interaction between the cavity field and a control two-level atom. The possible implementation of the schemes is finally discussed.
Gravitational Waves from an Axion-Dark Photon System: A Lattice Study
2021
In this work, we present a lattice study of an axion - dark photon system in the early Universe and show that the stochastic gravitational wave (GW) background produced by this system may be probed by future GW experiments across a vast range of frequencies. The numerical simulation on the lattice allows us to take into account non-linear backreaction effects and enables us to accurately predict the final relic abundance of the axion or axion-like particle (ALP) as well as its inhomogeneities, and gives a more precise prediction of the GW spectrum. Importantly, we find that the GW spectrum has more power at high momenta due to $2\rightarrow1$ processes. Furthermore, we find the degree of po…