Two-time synchronism and induced synchronization in a Kerr coupler

A pair of interacting Kerr oscillators treated as a master coupler sending chaotic or hyperchaotic signals to its slave copy is considered. We synchronize a with A and b with B through two communication channels and . The effect of synchronization is non-simultaneous, the pairs and have different times of synchronization. It is possible to synchronize an individual pair, for example, when its communication channel is turned off, provided that the second channel for the pair is turned on. The resulted synchronization is termed induced. The efficiencies of the presented synchronization precesses are studied.Received: 20 February 2003, Published online: 29 April 2003PACS: 05.45.Xt Synchronizations; coupled oscillators - 05.45.Pq Numerical simulations of chaotic systems - 42.65.Sf Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatio-temporal dynamics     

Metastable level lifetimes from electron-shelving measurements with ion clouds and single ions

The lifetime of the -level in singly-ionized calcium has been measured by the electron-shelving technique on different samples of rf trapped ions. The metastable state has been directly populated by exciting the dipole-forbidden transition. In ion clouds, the natural lifetime of this metastable level has been measured to be ( ) ms. For the single-ion case, we determined a lifetime of ( ) ms. The -error bars at the 2%-level have different origins for the two kinds of experiments: data fitting methods for lifetime measurements in an ion cloud and control of experimental parameters for a single ion. De-shelving effects are extensively discussed. The influence of differing approaches for the processing of the single-ion quantum jump data on the lifetime values is shown. Comparison with recent measurements shows excellent agreement when evaluated from a given method.Received: 14 November 2003, Published online: 24 February 2004PACS: 32.70.Cs Oscillator strengths, lifetimes, transition moments - 32.80.Pj Optical cooling of atoms, trapping     

Studies of ion energy and yield from argon clusters heated by intense femtosecond laser pulses

Using time-of-flight spectrometry, the interaction of intense femtosecond laser pulses with argon clusters has been studied by measuring the energy and yield of emitted ions. With two different supersonic nozzles, the dependence of average ion energy on cluster size in a large range of has been measured. The experimental results indicate that when the cluster size , the average ion energy Coulomb explosion is the dominant expansion mechanism. Beyond this size, the average ion energy gets saturated gradually, the clusters exhibit a mixed Coulomb-hydrodynamic expansion behavior. We also find that with the increasing gas backing pressure, there is a maximum ion yield, the ion yield decreases as the gas backing pressure is further increased.     

Accurate asymptotic ground state potential curves of Cs$\mathsf{_2}$ from two-colour photoassociation

Over 100 high lying level energies of the lowest electronic states and in Cs₂ are determined in a -like scheme two-colour photoassociation spectroscopy. The results are analyzed with a coupled channel model using an asymptotic approach, based on nodal lines. From this analysis we determine the long range dispersion coefficient C₆ to 6846.2 15.6 a.u. We also obtain the first experimental determination of the amplitude of the asymptotic exchange term.Received: 4 November 2003, Published online: 20 January 2004PACS: 34.20.-b Interatomic and intermolecular potentials and forces, potential energy surfaces for collisions - 32.80.Pj Optical cooling of atoms; trapping - 03.65.Ge Solutions of wave equations: bound states     

Exclusive semileptonic rare decays $B \to K^{(*)} l^ + l^-$ in a SUSY SO(10) GUT

In the SUSY SO(10) GUT context, we study the exclusive processes . Using the Wilson coefficients of the relevant operators including the new operators which are induced by neutral Higgs boson (NHB) penguins, we evaluate some possible observables associated with these processes like the invariant mass spectrum (IMS), lepton pair forward-backward asymmetry (FBA), lepton polarization asymmetries etc. In this model the contributions from Wilson coefficients , among new contributions, are dominant. Our results show that the NHB effects are sensitive to the FBA, , and of decay, which are expected to be measured in B factories, the deviation of in can reach 0.1 from SM, which could be seen in B factories, and the average of the normal polarization can reach several percent for and it is 0.05 or so for , which could be measured in the future super B factories and provide useful information to probe new physics and discriminate different models.Received: 30 October 2004, Published online: 9 March 2005     

An analysis of the time-dependent CP asymmetryin $B \to \pi \pi$ decays in the standard model

Measurements of the time-dependent CP-asymmetry in the decay and its charge conjugate by the BELLE and BABAR collaborations currently yield and , characterizing the direct and mixing-induced CP-asymmetries, respectively. We study the implication of these measurements on the CKM phenomenology taking into account the available information in the quark mixing sector. Our analysis leads to the results that the ratio |P _c /T _c | involving the QCD-penguin and tree amplitudes and the related strong phase difference in the decays are quite substantial. Using the isospin symmetry to constrain |P _c /T _c | and , where parameterizes the penguin-induced contribution, we present a fit of the current data including the measurements of and . Our best-fits yield , , , , and . At 68% C.L., the ranges are , , , and . Currently en vogue dynamical approaches to estimate the hadronic matrix elements in decays do not provide a good fit of the current data.Received: 5 April 2004, Published online: 14 July 2004A.Ya. Parkhomenko: On leave of absence from Department of Theoretical Physics, Yaroslavl State University, Sovietskaya 14, 150000 Yaroslavl, Russia.     

Modular construction of special mixed quantum states

For a homogeneous quantum network of N subsystems with n levels each we consider separable generalized Werner states. A generalized Werner state is defined as a mixture of the totally mixed state and an arbitrary pure state : with a mixture coefficient . For this density operator to be separable, will have an upper bound . Below this bound one should alternatively be able to reproduce by a mixture of entirely separable input-states. For this purpose we introduce a set of modules, each contributing elementary coherence properties with respect to a generalized coherence vector. Based on these there exists a general step-by-step mixing process for any . For being a cat-state it is possible to define an optimal process, which produces states right up to the separability boundary ( ).Received: 3 December 2002, Published online: 29 July 2003PACS: 03.65.Ud Entanglement and quantum nonlocality (e.g. EPR paradox, Bells inequalities, GHZ states, etc.) - 03.67.-a Quantum information - 03.65.-w Quantum mechanics     

Decelerated molecular beams for high-resolution spectroscopy

Ultimately, the resolution of any spectroscopic experiment is limited by the interaction time between the particles that are to be examined and the measuring device. The obtainable spectroscopic resolution in a molecular beam experiment can be considerably improved using samples of slow molecules, as produced, for example, in a Stark-decelerator. This is demonstrated here by measuring the inversion tunneling spectrum of using a pulsed molecular beam that has been decelerated to about 52 m/s. Hyperfine resolved inversion transitions in in the state (around 1.43 GHz) are induced in a microwave region, and molecules that have undergone the transition are subsequently detected using a UV-laser based ionization detection scheme. To increase the signal intensity, the decelerated molecular beam is both transversally and longitudinally focused into the laser detection region. The observed spectral width of individual hyperfine transitions in the fully resolved spectrum is about 1 kHz, and the standard deviation of the best fit is 62 Hz.Received: 7 September 2004, Published online: 23 November 2004PACS: 33.15.Pw Fine and hyperfine structure - 33.20.Bx Radio-frequency and microwave spectra - 33.40. + f Multiple resonances - 33.70.Jg Line and band widths, shapes, and shifts - 39.10. + j Atomic and molecular beam sources and techniques     

The $\beta$-function in duality-covariant non-commutative $\phi^4$-theory

We compute the one-loop -functions describing the renormalisation of the coupling constant and the frequency parameter for the real four-dimensional duality-covariant non-commutative -model, which is renormalisable to all orders. The contribution from the one-loop four-point function is reduced by the one-loop wavefunction renormalisation, but the -function remains non-negative. Both and vanish at the one-loop level for the duality-invariant model characterised by . Moreover, also vanishes in the limit , which defines the standard non-commutative -quantum field theory. Thus, the limit exists at least at the one-loop level.Received: 19 March 2004, Published online: 5 May 2004     

Electron impact excitation of 2p and 3p states of hydrogen at intermediate energies

The recent theoretical work by Bartlett et al. [J. Phys. B 38, L95 (2005)] and the latest measurements on the reduced Stokes parameters , and for 54.4 eV electron impact excitation of the 2p state atomic hydrogen by Williams and Mikosza [J. Phys. B 39, 4113 (2006)] has motivated the present work. A coupled-channel-optical calculation with 9 and 12 atomic states supplemented with the continuum optical potentials for the stronger coupling channels has been performed. The calculated n = 2 and n = 3 differential cross sections and the reduced Stokes parameters are comparable with the state-of-the art calculations. There is closer agreement between the present calculations and the experimental measurements for the reduced Stokes parameters and in the n = 2p excitation at 54.4 eV. The present CCO calculations also display good accord with the limited experimental data for the reduced Stokes parameters in the n=3p excitation.     

Multiple ionization effects on L X-ray intensity ratios in Hf,Ta, Re,Ir, Pt,Au and Pb due to proton bombardment at energies 1-5 MeV

The L X-ray intensity ratios in the elements Hf, Ta, Re, Ir, Pt, Au and Pb due to proton bombardment at energies from 1 to 5 MeV are measured and compared with the ECPSSR theoretical intensity ratios. The L /L _l intensity ratios obtained in the present work are in good agreement with theoretical values while the L /L and L /L intensity ratios are consistently lower than the theoretical values. This deviation may be explained in terms of multiple ionization effects in M, N and O shells.Received: 27 March 2004, Published online: 6 July 2004PACS: 32.80.Hd Auger effect and inner-shell excitation or ionization - 32.30.Rj X-ray spectra - 41.75.-i Charged-particle beams - 41.75.Ak Positive-ion beams     

Triple differential cross-sections of Ne (2s<Superscript>2</Superscript>) in coplanar to perpendicular plane geometry

The distorted wave Born approximation (DWBA) with the spin averaged static exchange potential has been used to calculate the triple differential cross-sections (TDCSs) for Ne (2s ²) ionization by electron impact in coplanar to perpendicular plane symmetric geometry at 110.5 eV incident electron energy. The present theoretical results at gun angles (coplanar symmetric geometry) and (perpendicular plane geometry) are in satisfactory agreement with the available experimental data. A deep interference minimum appears in the TDCS in the coplanar symmetric geometry and a strong peak at scattering angle caused by the single collision mechanism has been observed in the perpendicular plane geometry. The TDCSs at the gun angles , and are predicted.Received: 16 July 2002, Published online: 22 July 2003PACS: 34.80.Gs Molecular excitation and ionization by electron impact - 34.80.Dp Atomic excitation and ionization by electron impact     

The high-energy critical minimum in elastic electron scattering by argon

The position of high-energy critical minimum in elastic electron-argon scattering was investigated both experimentally and theoretically. Differential cross-sections (DCSs) were measured as a function of both incident electron energy (40-150 eV) and scattering angle ( ), in small steps around the critical minimum. The position of the high-energy critical minimum in elastic electron-argon scattering was experimentally found to be at eV and . To cover the energy and angular ranges of the present experiment, relevant relativistic ab initio calculations were carried out, based on the Dirac-Hartree-Fock method with the exchange calculated exactly. Target polarization is described by an ab initio potential taken from relativistic polarized orbital calculations. The calculated position of the high-energy critical minimum is eV, . It was shown that even slight difference of fixed scattering angle close to the critical point could affect significantly the energy dependent DCS. Discussion of behavior of DCS in the vicinity of the critical minimum was performed including convolution analysis in both energy and angle.Received: 31 October 2003, Published online: 20 April 2004PACS: 31.15.Ar Ab initio calculations - 34.80.Bm Elastic scattering of electrons by atoms and molecules     

Lifetime vibrational interference during the NO 1s-1π* resonant excitation studied by the NO+(A 1Π → X 1Σ+) fluorescence

Dispersed fluorescence from fragments formed after the de-excitation of the 1s^-1π^* resonances of N^*O and NO^* has been measured in the spectral range of 118–142 nm. This range is dominated by lines of atomic nitrogen and oxygen fragments and by the bands in the NO⁺ ion which result from the participator Auger decay of the 1s^-1π^* resonances. Ab-initio calculations of the transition probabilities between vibrational levels during the reaction NO N^*O ⇒ NO were used to explain the observed intensity dependence for the fluorescence bands on the exciting-photon energy across the resonances and on both v^′ and v^′′ vibrational quantum numbers. The multiplet structure of the 1s^-1π^* resonance and lifetime vibrational interference explain the observed exciting-photon energy dependence of the fluorescence intensity. A strong spin-orbit coupling between singlet and triplet states of NO⁺ is proposed to reduce additional cascade population of the state via radiative transitions from the and states and to explain remaining differences between measured and calculated integral fluorescence intensities.     

Amplitude-squared squeezing in superposed coherent states

We study amplitude-squared squeezing of the Hermitian operator Z_θ=Z₁ cosθ+Z₂ sin θ, in the most general superposition state , of two coherent states and . Here operators Z_1,2 are defined by , a is annihilation operator, θ is angle, and complex numbers C_1,2 , α, β are arbitrary and only restriction on these is the normalization condition of the state . We define the condition for a state to be amplitude-squared squeezed for the operator Z_θ if squeezing parameter , where N=a⁺a and . We find maximum amplitude-squared squeezing of Z_θ in the superposed coherent state with minimum value 0.3268 of the parameter S for an infinite combinations with α- β= 2.16 exp [±i(π/4) + iθ/2], and with arbitrary values of (α+β) and θ. For this minimum value of squeezing parameter S, the expectation value of photon number can vary from the minimum value 1.0481 to infinity. Variations of the parameter S with different variables at maximum amplitude-squared squeezing are also discussed.     

Study of Z pair production and anomalous couplingsin e + e- collisions at $\sqrt{s}$ between 190 GeV and 209 GeV

A study of Z-boson pair production in e ⁺ e^- annihilation at center-of-mass energies between 190 GeV and 209 GeV is reported. Final states containing only leptons, ( and ), quark and lepton pairs, ( , ) and only hadrons ( ) are considered. In all states with at least one Z boson decaying hadronically, lifetime, lepton and event-shape tags are used to separate pairs from final states. Limits on anomalous ZZ and ZZZ couplings are derived from the measured cross sections and from event kinematics using an optimal observable method. Limits on low scale gravity with large extra dimensions are derived from the cross sections and their dependence on polar angle.Received: 14 July 2003, Published online: 18 December 2003     

Spectroscopic studies of NaCs for the ground state asymptote of Na + Cs pairs

The ground state X of NaCs was studied by laser induced fluorescence Fourier-transform spectroscopy. An accurate potential energy curve was derived from more than 5000 transitions. This potential reproduces the experimental observations within their uncertainties of cm^-1 and covers about 99.97% of the potential well depth. Few vibrational levels of the shallow state a below the atomic ground state asymptote were observed. The identification is mainly done by the observed and quantitatively interpreted molecular hyperfine structure applying atomic parameters of the ground states of Na and Cs. An estimated potential curve for a is reported which can be used together with that of X for coupled channel calculations of cold collisions between Na and Cs. An example is given. Electronic supplementary material to this article is available at and is accessible for authorized users. Received: 10 September 2004, Published online: 23 November 2004 PACS: 31.50.Bc Potential energy surfaces for ground electronic states - 33.20.Kf Visible spectra - 33.20.Vq Vibration-rotation analysis - 33.50.Dq Fluorescence and phosphorescence spectra Supplementary tables (Tabs. I-III) are only available in electronic form at http: //www.eurphysj.org     

Ion-acoustic solitons and double-layers in a plasma consisting of positive and negative ions with non-thermal electrons

In this research paper, the authors have studied the properties of ion-acoustic solitons and double-layers in a plasma consisting of warm positive and negative ions with different concentration of masses, charged states and non-thermal electrons using small amplitude approximation. Reductive perturbation method is used to derive KdV and m-KdV equations. Existence of ion-acoustic solitons and double-layer is explored over a wide range of parameter space. The role of non-thermal electrons characterized by finite is investigated. It is observed that for a particular value of , there is a transition from compressive to rarefactive solitons. However, when is increased beyond a critical value, no double-layers are obtained. The significance of relative ion masses is also investigated.Received: 9 July 2004, Published online: 21 September 2004PACS: 52.35.-g Waves, oscillations, and instabilities in plasmas and intense beams     

Exotic baryons and monopole excitations in a chiral soliton model

We compute the spectra of exotic pentaquarks and monopole excitations of thelow-lying and baryons in a chiral soliton model. Once the low-lying baryon properties are fit, the other states are predicted without any more adjustable parameters. This approach naturally leads to a scenario in which the mass spectrum of the next to lowest-lying states is fairly well approximatedby the ideal mixing pattern of the representation of flavor SU(3). We compare our results to predictions obtained in other pictures for pentaquarks and speculate about the spin-parity assignment for and .Received: 21 April 2004, Revised: 19 May 2004, Published online: 23 July 2004PACS: 12.39.Dc Skyrmions - 14.20.-c Baryons (including antiparticles) - 14.80.-j Other particles (including hypothetical)     

Boltzmann-Uehling-Uhlenbech calculation of total reaction cross-section and fragmentation cross-section

, and have been calculated via the BUU model with soft EOS and 0.8 times of . The density distribution without any adjustable parameters which comes from the RMF model has been introduced into the BUU calculation to replace the normally used one-parameter square-type distribution. The calculated results can reproduce the experimental data well for both halo- and stable-nuclei-induced reactions. Here or is calculated as the difference between of halo nucleus and core nucleus, by assuming . It indicates that this assumption works very well at high energy in the BUU calculation. More experimental measurements are necessary to test the validity of this assumption at intermediate energy.Received: 12 June 2003, Revised: 29 September 2003, Published online: 27 April 2004PACS: 24.10.-i Nuclear reaction models and methods - 25.60.Dz Interaction and reaction cross-sections - 25.60.Gc Breakup and momentum distributions - 27.20. + n