A nuclear optical potential on the Λ hyperon

A nuclear optical potential acting on the Λ hyperon is evaluated within the framework of the G-matrix theory and the local density approximation by employing the Nijmegen OBE model D interaction.     

Analisis of inelastic scattering of π-mesons from nuclei within the microscopic optical potential

Cross sections of inelastic scattering of π-mesons from Si, Ni, and Pb nuclei at energy T _lab = 291 MeV are calculated using the distorted wave approximation. The microscopic direct and transition optical potentials are determined by specifying the pion-nucleon scattering amplitude and the nuclear density distribution, where we use the in-medium πN amplitude parameters obtained earlier by analyzing the elastic scattering data for the same nuclei. The cross sections are calculated on the basis of the relativistic wave equation. The deformation parameters of the nuclei are obtained by comparing inelastic scattering cross sections with the appropriate experimental data.     

Accuracy of simple folding model in the calculation of the direct part of real α−α interaction potential

The direct part of real α?α interaction potential is calculated in the simple folding model using density-dependent Brink–Boeker effective interaction. The simple folding potentials calculated from the short- and finite-range components of this effective interaction are compared with their corresponding double folding results obtained from the oscillator model wave function to establish the relative accuracy of the model. It is found that the direct part of real α?α interaction potential calculated in the simple folding model is reliable.     

Tachyonization of the ΛCDM cosmological model

In this work a tachyonization of the ΛCDM model for a spatially flat Friedmann–Robertson–Walker space–time is proposed. A tachyon field and a cosmological constant are considered as the sources of the gravitational field. Starting from a stability analysis and from the exact solutions for a standard tachyon field driven by a given potential, the search for a large set of cosmological models which contain the ΛCDM model is investigated. By the use of internal transformations two new kinds of tachyon fields are derived from the standard tachyon field, namely, a complementary and a phantom tachyon fields. Numerical solutions for the three kinds of tachyon fields are determined and it is shown that the standard and complementary tachyon fields reproduces the ΛCDM model as a limiting case. The standard tachyon field can also describe a transition from an accelerated to a decelerated regime, behaving as an inflationary field at early times and as a matter field at late times. The complementary tachyon field always behaves as a matter field. The phantom tachyon field is characterized by a rapid expansion where its energy density increases with time.     

Accurate potential energy curves and spectroscopic properties of the 27 Λ-S states and 73 Ω states of the PO radical

The potential energy curves (PECs) were calculated for the 27 Λ-S states and 73 Ω states of PO radical. The calculations were done using the CASSCF method, which was followed by the internally contracted multireference configuration interaction (icMRCI) approach. To improve the quality of PECs, core-valence correlation and scalar relativistic corrections as well as Davidson correction were included. Of the 27 Λ-S states, the 1⁶Σ⁺ state was repulsive at any case. The 1⁴Φ and 1⁶Π states were bound, but they became repulsive with the spin-orbit coupling (SOC) effect accounted for. The 3⁴Σ⁺, a⁴Π, C′²Δ, D′²Π, 1⁴Δ, 1²Φ, 1⁶Σ⁺ and 1⁶Π states were inverted with the SOC effect included. The F²Σ⁺ state had double wells. The avoided crossings existed between the B²Σ⁺ and F²Σ⁺ states, the F²Σ⁺ and 3²Σ⁺ states, the C′²Δ and 2²Δ states, the 1⁴Δ and 2⁴Δ states, the 2⁴Δ and 3⁴Δ states, the 2⁴Π and 3⁴Π states and the 3⁴Π and 4⁴Π states. The c⁴Σ⁺, 2⁴Σ⁺, 3⁴Σ⁺, 3⁴Π, 4⁴Π, 5⁴Π, 3⁴Δ, 1⁴Φ and 1⁶Π states were weakly bound, which well depths were within several hundred cm^?1. The spectroscopic parameters were derived. The SOC effect on the spectroscopic properties was evaluated. The spectroscopic results obtained here could be expected to be reliably predicted ones.     

The hyperon-nucleon interaction potential in the bound-state soliton model: the ΛN case

We develop the formalism to study the hyperon-nucleon interaction potential within the bound-state approach to the SU(3) Skyrme model. The general framework is illustrated by applying it to the diagonal ΛN potential. The central, spin-spin and tensor components of this interaction are obtained and compared with those derived using alternative schemes.     

Electromagnetically induced transparency of single Λ-type three-level atom in high-finesse optical cavity

We study the features of the electromagnetically induced transparency (EIT) in a single Λ-type three-level atom placed in a high finesse cavity under the action of a coupling laser and a probe laser. Our calculations show that three transparency windows appear when the pump strength is big enough. It can be explained by the residual pump in the cavity resulting mostly in the energy splitting. Level |3〉is split into four slightly different energy levels. An interference takes place between excitation pathways. Furthermore, it is also shown that the frequencies of the EIT windows can be tuned by changing the coupling field detuning Δ₂ and the reflection profile is very sensitive to the cavity field detuning Δ_c.     

Improved analysis of the rare decay processes of Λ_b

It is noted that in the new Particle Data Group(PDG) version the rare decays of the Λ_b baryon have been revised with more accuracy. The new results show that most of the existing theoretical results on the process Λ_b→Λ_γ Lgbare larger than those of experiments. With the improved higher-order light-cone distribution amplitudes of the Λ baryon, we reanalyze the process in the framework of light-cone quantum chromodynamics sum rules and the branching ratio is estimated to be Br (Λ_b→Λ_γ)=(7.38_(-0.39)~(+0.40))×10~(16), which is consistent with the new experimental result. Furthermore, another process Λ_b→Λl~+l~- is also analyzed in the same frame. The final branching ratio is calculated to be Br (Λ_b→Λl~+l~-)=1.20×10~(-6), which is in good accordance with the data from the PDG and other theoretical predictions.     

The second order optical potential for theπd system at the threshold

The second order optical potential for thed system is derived in the framework of the Watson formalism and applied to the calculation of the 1s-state energy shift of the atom and thed scattering lengtha _d . The results are in good agreement with those of the Faddeev type calculations.The authors wish to thank V. B. Belyaev, R. Mach, M. G. Sapozhnikov and R. A. Eramzhyan for stimulating discussions and helpful advice.     

Controlling the optical bistability in a Λ-type atomic system via incoherent pump field

We investigated optical bistability (OB) and the absorption properties of a weak probe field in a three-level Λ-type atomic system confined in a unidirectional ring cavity via incoherent pump field. We found that the threshold of OB and the probe field absorption can be controlled by the rate of incoherent pump field. No laser field was used in the pumping processes.     

Validity of the Franck-Condon principle in the optical spectroscopy: optical conductivity of the Fröhlich polaron

The optical absorption of the Fr?hlich polaron model is obtained by an approximation-free diagrammatic Monte Carlo method and compared with two new approximate approaches that treat lattice relaxation effects in different ways. We show that: (i) a strong coupling expansion, based on the Franck-Condon principle, well describes the optical conductivity for large coupling strengths (alpha > 10); (ii) a memory function formalism with phonon broadened levels reproduces the optical response for weak coupling strengths (alpha < 6) taking the dynamic lattice relaxation into account. In the coupling regime 6 < alpha < 10, the optical conductivity is a rapidly changing superposition of both Franck-Condon and dynamic contributions.     

An potential from analysis of ground and excited states of four-particle hypernuclei and Λp-scattering

A joint theoretical analysis is made of the binding energies of the ground and excited states of the four-particle hypernuclei and and the cross sections of low-energy p-scattering. We propose concrete variants of paired central spin-and charge-dependent n-potentials which are consistent with experiment.Translated from Izvestiya Vyssikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 62–65, May, 1982.     

Diffractive-optical processing of temporal signals, part Ⅱ: optical tapped-delay line

The topic of this presentation is the utilization of time for optical information processing. As clock rates in computing and communication systems increase and reach the THz border, optical techniques for signal filtering, shaping and clock distribution become attractive. We discuss the use of optics in temporal processing and consider in particular diffractive solutions. In this paper, we describe the use of double diffraction for implementing an ultrafast tapped-delay line.     

Impurity effects of the Λ hyperon in the hypernuclear systems Λ25Mg and Λ29Si

Based on the beyond-mean-field Skyrme-Hartree-Fock model,impurity effects of the Λ hyperon in the hypernuclear systems Λ25Mg and Λ29Si are investigated,respecti...     

A variational approach to the modulational-oscillatory instability of Bose–Einstein condensates in an optical potential

We use the time-dependent variational approach to demonstrate how the modulational and oscillatory instabilities can be generated in Bose–Einstein condensates (BECs) trapped in a periodic optical lattice with weak driving harmonic potential. We derive and analyze the ordinary differential equations for the time evolution of the amplitude and phase of the modulational perturbation, and obtain the instability condition of the condensates through the effective potential. The effect of the optical potential on the dynamics of the BECs is shown. We perform direct numerical simulations to support our theoretical findings, and good agreement is found.     

Electromagnetically induced transparency of single Λ-type three-level atoms in a high-finesse optical cavity

We study the features of electromagnetically induced transparency(EIT) in a single Λ-type three-level atom placed in a high-finesse cavity under the action of a coupling laser and a probe laser.Our calculations show that three transparency windows appear when the pump strength is large enough.This can be explained by the residual pump in the cavity mostly resulting in energy splitting.The level |3 is split into four slightly different energy levels,and interference takes place between the excitation pathways.Furthermore,it is also shown that the frequencies of the EIT windows can be tuned by changing the coupling field detuning 2,and that the reflection profile is very sensitive to the cavity field detuning △c.     

Stability of trapped Bose-Einstein condensates in one-dimensional tilted optical lattice potential

Using the direct perturbation technique,this paper obtains a general perturbed solution of the Bose-Einstein condensates trapped in one-dimensional tilted optical lattice potential. We also gave out two necessary and sufficient conditions for boundedness of the perturbed solution. Theoretical analytical results and the corresponding numerical results show that the perturbed solution of the Bose-Einstein condensate system is unbounded in general and indicate that the Bose-Einstein condensates are Lyapunov-unstable. However,when the conditions for boundedness of the perturbed solution are satisfied,then the Bose-Einstein condensates are Lyapunov-stable.     

Alternative methods for measurement of the global polarization of Λhyperons

We propose alternative methods for measurement of the global polarization of Λ hyperons. These methods involve event averages of proton and Λ momenta in the laboratory frame. We carry out simulations using these methods and show that all of them work equally well in obtaining the global polarization of Λ hyperons.