The kappa in J/Ψ↦K<Superscript>+</Superscript>π

BES II data for J/Ψ↦K ^*(890)Kπ reveal a strong κ peak in the Kπ S-wave near threshold. Both magnitude and phase are determined in slices of Kπ mass by interferences with strong K ₀(1430), K ₁(1270) and K ₁(1400) signals. The phase variation with mass agrees within errors with LASS data for Kπ elastic scattering. A combined fit is presented to both BES and LASS data. The fit uses a Breit-Wigner amplitude with an s-dependent width containing an Adler zero. The κ pole is at (760±20(stat)±40(syst)) - i(420±45(stat)±60(syst)) MeV. The S-wave I = 0 scattering length a ₀ = 0.23±0.04 m _π ^-1 is close to the prediction 0.19±0.02 m _π ^-1 of Chiral Perturbation Theory at O(p ⁴). An erratum to this article can be found at .     

Long <Emphasis FontCategory="NonProportional">K</Emphasis><Superscript>π</Superscript> = 0<Superscript>+</Superscript> and 4<Superscript>−</Superscript> bands in deformed nuclei

Experimental data on some long bands in N=88–98 deformed nuclei are analyzed on the basis of a method systematizing the energies of levels and inertial parameters and a method employing the analogy between neighboring. Beta bands built on low-lying 0 ₂ ⁺ levels are identified in N=90 isotones, including the ¹⁵⁸Er, ¹⁶⁰Yb, and ¹⁶²Hf nuclei. Some of intermediate members of these bands have not been found yet. The systematic properties of 4^? bands are presented, and the dynamics of the inertial parameters of these bands in N=88–98 isotones is revealed. The bands are identified in ¹⁵⁸Yb, ¹⁵⁶Dy, ¹⁵⁶Er, ¹⁶²Yb, and ¹⁶⁶Hf.     

Analysis of Θproduction in K<Superscript>+</Superscript>- Xe collisions

The reaction K⁺XeK⁰pX is investigated in a meson-exchange model including rescattering of the secondary protons with the aim to analyze the evidence for the ⁺(1540)-resonance reported by the DIANA Collaboration. We confirm that the kinematical cuts introduced by the DIANA Collaboration efficiently suppress the background to the K⁺nK⁰p reaction which may contribute to the ⁺(1540) production. We find that these kinematical cuts do not produce a narrow structure in the K^0p effective-mass spectra near 1540 MeV. We study the effect of a narrow ⁺-resonance of both positive and negative parity in comparison with the DIANA data. We show that the K⁺XeK⁰pX calculations without ⁺ contribution as well as the results obtained with a ⁺ width of 1 MeV are in comparably good agreement with the DIANA results. More dedicated experiments are called for to establish this exotic baryon resonance.     

Two-neutrino positron double-beta decay of <Superscript>106</Superscript>Cd for the 0<Superscript>+</Superscript> → 0<Superscript>+</Superscript> transition

The two-neutrino positron double-beta decay of ¹⁰⁶Cd for the 0 ⁺ 0⁺ transition has been studied in the Hartree-Fock-Bogoliubov model in conjunction with the summation method. In the first step, the reliability of the intrinsic wave functions of ¹⁰⁶Cd and ¹⁰⁶Pd nuclei has been tested by comparing the theoretically calculated results for yrast spectra, reduced B(E2: 0⁺ 2⁺) transition probabilities, quadrupole moments Q(2⁺) and gyromagnetic factors g(2⁺) with the available experimental data. In the second step, the nuclear transition matrix element M₂ and the half-life T_1/2² for the 0 ⁺ 0⁺ transition have been calculated with these wave functions. Moreover, we have studied the effect of deformation on the nuclear transition matrix element M₂.     

Spin physics at e<Superscript>+</Superscript>e<Superscript>−</Superscript> colliders

A large number of measurement related to spin was performed during the last decade at the e ⁺ e ^? colliders LEP and SLC providing important information on the dynamics of high energy interactions. In this paper three main topics will be covered: the measurements of the electroweak couplings, the study of fragmentation dynamics and the search for physics beyond the Standard Model.     

Charge transfer in energetic Li<Superscript>2+</Superscript>–H and He<Superscript>+</Superscript>–He<Superscript>+</Superscript> collisions

The total cross sections for charge transfer in Li²⁺-H and He⁺-He⁺ collisions have been calculated, using the four body first Born approximation with correct boundary conditions (CB1-4B) and four body continuum distorted wave method (CDW-4B) in the energy range 10–5000 keV/amu. The role of dynamic electron correlations is examined as a function of the impact energy. The present results call for additional experimental data at higher impact energies than presently available.     

Gamow-Teller 1<Superscript>+</Superscript> states in <Superscript>112–124</Superscript>Sb isotopes

The violated supersymmetry property of the pairing interaction between nucleons were restored using the Pyatov method [Pyatov and Salamov, Nucleonica 22, 127 (1977)]. The eigenvalues and eigenfunctions of the restored Hamiltonian with the separable residual Gamow-Teller effective interactions in the particle-hole and particle-particle channels were solved within the framework of proton-neutron quasirandom phase approximation (pnQRPA). The Gamow-Teller resonance energies for ^112–124Sb isotopes and the differential cross-sections for Sn(³He, t)Sb reactions at E(³He) = 200 MeV occurring by the excitation of the Gamow-Teller resonance state were calculated. The calculated values were compared with other calculations and the corresponding experimental data.     

The evaluation of the branching ratios of the decays φ(1020)→2π<Superscript>+</Superscript>2π<Superscript>−</Superscript>π<Superscript>0</Superscript>, π<Superscript>+</Superscript>π<Superscript>−</Superscript>3π<Superscript>0</Superscript>

Combining the Okubo-Zweig-Iizuka rule in the decay φ→ρπ→π⁺π^?π⁰ with the ρ→4π decay amplitudes, we calculate the φ→2π⁺2π^?π⁰ and φ→π⁺π^?3π⁰ ones. The partial widths of the above φ decays are evaluated, and the excitation curves in e⁺e^? annihilation are obtained, assuming reasonable particular relations among the parameters characterizing the anomalous terms of the HLS Lagrangian. The evaluated branching ratios B_φ→π⁺_π^?_3π⁰ ≈ 2 × 10^?7 and B_φ→2π⁺_2π^?_π⁰ ≈ 7 × 10^?7 are such that, with the luminosity L=500 pb^?1 attained at DAΦNE φ factory, one may already possess about 1685 events of the decays φ→5π.     

On the <Emphasis Type="Italic">K</Emphasis><Superscript><Emphasis Type="Italic">π</Emphasis></Superscript> = 0<Superscript>+</Superscript> rotational bands in the <Superscript>178</Superscript>Hf nucleus

The results obtained by studying the angular distributions of gamma rays with respect to the neutron-beam axis in the reaction ¹⁷⁸Hf(n, n′γ) involving the deexcitation of the K ^π = 0⁺ rotational bands of ¹⁷⁸Hf are presented.New information about themultipole-mixing parameter δ in gamma transitions from the levels of these bands is obtained. The K ^π = 0₄⁺ band is constructed anew. The relationship between the parameter δ for the (2⁺0 _n −2⁺0₁) gamma transition and the energy gap Δ _n = E _lev(2⁺0 _n ) − E _lev(0⁺0 _n ), on one hand, and the quasiparticle structure of the rotational band, on the other hand, is discussed for ¹⁷⁸Hf on the basis of the quasiparticle-phonon model.     

Processes e<Superscript>+</Superscript>e<Superscript>−</Superscript> → π<Superscript>0</Superscript>(π<Superscript>0</Superscript>′) γ in extended NJL model

The processes of electron-positron annihilation into π⁰γ and into π′(1300)γ are considered within an extended NJL model. The intermediate vector mesons ρ ⁰, ω ρ′(1450), and ω(1420) are taken into account. The latter two mesons are treated as the first radial excited states. They are incorporated into the NJL model by means of a polynomial form factor. Numerical predictions for the cross-sections of these processes are received for the center-of-mass energies below 2 GeV. Our results for the π⁰γ production are in agreement with experimental data obtained in the energy region 600–1020 MeV.     

(EC + β<Superscript>+</Superscript>) decays of the 11/2<Superscript>-</Superscript> isomer and 1/2<Superscript>+</Superscript> ground state of <Superscript>143</Superscript>Dy

The 1/2⁺ ground state and a 11/2^- isomer of very neutron-deficient isotope ¹⁴³Dy were produced by irradiation of an enriched target of ¹⁰⁶Cd with ⁴⁰Ca and studied by using a helium-jet fast tape-transport system in combination with proton-γ, X-γ and γ-γ coincidence measurements. A simple ( EC + β⁺) decay scheme of ^143mDy with a half-life of 3.0(3) s and a tentative ( EC + β⁺) decay scheme of ^143gDy with a half-life of 5.6(10) s are proposed. As a by-product, the 347- and 545-keV γ transitions in ¹³⁸Sm following the β-delayed proton emission of ¹³⁹Gd decay and the 323-keV γ transition in ¹³⁹Eu following the β-delayed proton emission of ¹⁴⁰Tb decay could be observed for the first time. Received: 20 August 2002 / Accepted: 28 October 2002 / Published online: 11 February 2003 RID="a" ID="a"e-mail: xsw@ns.lzb.ac.cn Communicated by D. Schwalm     

Photoproduction of π<Superscript>0</Superscript>π<Superscript>+</Superscript> pairs on proton and deuteron

The reaction of π⁰π⁺ photoproduction on free and quasi-free protons with γ-ray energies from 0.5 to 1.5 GeV has been studied. Its cross section was measured in the range θ _π ⁰ ≥ 20°. The distributions of π⁰π⁺, π⁰n, and π⁺n invariant masses were analyzed. The experiment was performed using the Compton back-scattered γ-ray beam at the GRAAL facility (Grenoble, France), applying liquid deuterium and hydrogen targets and a large-aperture (almost 4π) detector. Particular attention was paid to analysis of systematic errors related to the neutron detection efficiency.     

Emission spectroscopy of the A<Superscript>1</Superscript>Π–X<Superscript>1</Superscript>Σ<Superscript>+</Superscript> system of AlH

The high-resolution emission spectrum of the A¹ Π–X¹Σ⁺ transition of AlH was observed in the 18 000–25 000 cm^-1 spectral region using a conventional spectroscopic technique. The AlH molecules were excited in an Al hollow-cathode lamp filled with a mixture of Ne carried gas and a trace amount of NH₃. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. In total 163 transition wave numbers belonging to six bands (0-0,1 and 1-0,1,2,3) were precisely measured and rotationally analysed. In the final fit the present data have been combined with available high-resolution measurements of the vibration-rotation bands by White et al. [J. Chem. Phys. 99, 8371 (1993)]. This procedure enabled extracting molecular constants for the A¹ Π and X¹ Σ⁺ states of AlH. A very slight local perturbation has been discovered in the v=1 vibration level of the A¹ Π state at J=5. This was probably caused by the interaction with the a³Π state.     

Potential energy of <Superscript>∞</Superscript>H<Stack><Subscript>2</Subscript><Superscript>-</Superscript></Stack>(<Superscript>2</Superscript>∑<Stack><Subscript>u</Subscript><Superscript>+</Superscript></Stack> in the bound-state region

An accurate calculation of the lowest negative electronic state of H ₂ ^- (fixed nuclei) is reported using the CCSD(T) method and doubly augmented cc-pv5z basis set. Comparison has been made with the reference data by Senekowitsch et al. [Chem. Phys. Lett. 111 (1984) 211]. Owing to larger size of the basisset and inclusion of triple excitations, no vertical shift in this work is necessary to reproduce the asymptotics of H + H ^-. In addition, the effect of basis-set truncation is estimated, based on the complete-basis-set extrapolation method. The contribution of correlated electron-proton motion to the electron-energy curve for H₂ ^– dynamics is pointed out.Dedicated to Prof. Jií Horáek on the occasion of his 60th birthday.     

Inversion of the <Emphasis Type="Italic">K</Emphasis><Superscript>π</Superscript>=1<Superscript>−</Superscript> states in <Superscript>156</Superscript>Gd and <Superscript>170</Superscript>Yb

For the ¹⁵⁶Gd and ¹⁷⁰Yb nuclei, where the inversion of levels in the K^π=1^? bands is observed, the energies of rotational levels are calculated on the basis of the Coriolis interaction model for the states of two bands whose quantum numbers are K^π=1^?. New 0^? levels are introduced in ¹⁷⁰Yb, and the structure of ¹⁷⁰Er is refined. The interaction parameters calculated for six nuclei are considered within the structure predicted by the quasiparticle-phonon model.     

Laser control of the low-temperature <Emphasis Type="Italic">e</Emphasis><Superscript>−</Superscript>+O<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> reaction

The dissociative recombination theory of slow electrons with molecular ions in a strong monochromatic light field is developed. Classifications of all possible transitions and reaction mechanisms are presented. The potential energy curves of the oxygen molecule O₂^** dissociative states and partial cross sections are calculated.     

Stereodynamics of the reaction He+H<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> → HeH<Superscript>+</Superscript> + H: a theoretical study

Quasiclassical trajectory method for the title reaction He +H₂⁺ → HeH⁺ + H was carried out on the potential energy surface which was revised by Aquilanti et al. [Chem. Phys. Lett. 469, 26 (2009)]. The initial vibrational quantum number of reactant was set as v=1, v=2 and v=3. Stereodynamics information of the reaction was obtained, such as the distributions of product angular momentum P(θ _r ), P(ϕ _r ),p(ϕ _r , θ _r ) and the two commonly used polarization-dependent differential cross sections (PDDCSs) (2π/σ)(dσ ₀₀/dω _t ) and (2π/σ)(dσ ₂₀/dω _t ), to get the alignment and orientation of product molecules. The results show that the influence of both the collision energy and vibrational quantum number (v) to the reaction are highly sensitive.     

Statistical hadronization with exclusive channels in e<Superscript>+</Superscript>e<Superscript>−</Superscript> annihilation

We perform a systematic analysis of exclusive hadronic channels in e⁺e⁻ collisions at center-of-mass energies between 2.1 and 2.6 GeV within the statistical hadronization model. Because of the low multiplicities involved, calculations have been carried out in the full microcanonical ensemble, including conservation of energy-momentum, angular momentum, parity, isospin, and all relevant charges. We show that the data are in an overall good agreement with the model for an energy density of about 0.5 GeV/fm³ and an extra-strangeness suppression parameter γ _S ∼0.7, essentially the same values found with fits to inclusive multiplicities at higher energy.     

An analytical model of P <Superscript>+</Superscript>InAsSbP/n <Superscript>0</Superscript>-InAs/n <Superscript>+</Superscript>-InAs single heterojunction photodetector for 2.4–3.5 μm region

In this paper, a surface illuminated InAsSbP/InAs photodetector has been analyzed for operation in 2.0–3.5 m wavelength region. The influence of different dark current components on the resistance-area product (RA) of the photodetector has been estimated theoretically. The results obtained on the basis of the model are found to be in good agreement with the experimental data reported by others. The high value of detectivity of the device at room temperature will make it attractive for use in optical gas sensor.