N¯N annihilation into two mesons — The effect of the pion radial wavefunction

N¯ N (S-wave) annihilation into twos-wave mesons is treated as a two step process. The first stage involves a singleq¯ q ³P₀-vertex to give a two meson state (ones-wave and onep-wave meson in a relatives-state). The second stage is a meson-meson scattering mechanism producing the final twos-wave mesons in a relativep-wave. The new feature in this work is to study the effect of using a pion wavefunction whose radial form is different to that of the others- andp-wave mesons. This modification over earlier work results in a better understanding of the experimental branching ratios.     

Search for exotic mesons produced by baryon exchange in the reaction π+p → Λ + x++ at 12 GeV/c

A search for exotic mesons has been carried out at the CERN Omega spectrometer. The baryon-exchange reaction π⁺p → Λ + x⁺⁺ was studied at 12 GeV/c incident beam momentum. No evidence was found for the existence of doubly-charged strange mesons. The upper limit (95% confidence level) for this reaction is 60 nb for exotic mesons with squared masses from 1 to 7 (GeV/c²)² and 150 nb for 7 to 13 (GeV/c²)². These limits are of the same order of magnitude as the exotic cross-sections expected from two-component duality arguments.     

Neutral K1(890) and ρ0 meson production in e+e− annihilation at ;s=29GeV

The production of neutral K¹(890) and ρ⁰ mesons was studied in e⁺e^? annihilation at $\text{s}\text{=29}\text{GeV}$ using the High Resolution Spectrometer at PEP. Differential cross sections are presented as a function of the scaled energy variable z and compared to π⁰ and K⁰ production. The measured multiplicities are 0.84±0.08 ?⁰ mesons and $\text{0.57±0.09 K}{}^{10}\text{(890)}$ mesons per event for a meson momentum greater than 725 MeV/c. The ratios of vector meson to pseudoscalar meson production for (u,d), s and c quark are compared to predictions of the Lund model.     

Global predictions of T2 symmetric deep level wavefunctions in semiconductors

Numerical results of T₂ symmetric SP₃ bonded deep level wavefunctions due to short range defect potentials in Si, Ge, GaAs and InP are presented. The general features of defect wavefunctions are insensitive to either the band structure of the host of defect energy level. The total occupation probability of wavefunction located on 0 . 1 . 2 shells around the defect center is about 60–85%. This part of wavefunction may be expressed in several simple symmetric combinations of SP³ hybrid orbitals. The rest part of the wavefunction extends diversely over a wide range of space.     

Final states with a neutral meson and a π+π− or pp pair in pp interactions at 7.2 GeV/c

Cross sections are reported for $\text{p}\text{p}$ interactions at 7.2 GeV/c beam momentum yielding one of the mesons ?⁰, ω, ?, η or η′; together with a gp⁺π^? pair or a $\text{p}\text{p}$ pair. Results are compared with data on similar $\text{p}\text{p}$ interactions at other beam momenta. The angular distributions for the final states with a ?⁰ or ω clearly show a peripheral behaviour. Our results may be understood within the framework of the quark model, but differ from the predictions of the quark rearrangement model. Deviations from ideal mixing of vector mesons are discussed. The energy dependence of ?⁰ and ω production is compared with that of analogous pp and π^±p interactions.     

Backward production of ϱ0 and f0 mesons in π+n interactions at 6 GeV/c

Backward production of ?⁰ and f⁰ mesons in π⁺n interactions at 6 GeV/c is presented. Total and differential cross sections are reported along with spin density matrix elements.     

An appraisal of the molecular model for the vk centre

The V_k centre in halide crystals is often described in terms of an X₂^? molecule ion. Recent molecular calculations for the halogen molecule negative ions have enabled a detailed comparison to be made between the theoretical anion and the results from optical and spin resonance studies on the crystals. The optical absorption line widths are naturally dependant on the host lattice, but the excitation energies and spin resonance constants may be readily interpreted in terms of the molecule. Certain anomalies in the spin resonance data for the heteronuclear defects, in particular ClI^? and BrI^?, show that the simple wavefunction constructed from “s” and “p” atomic orbitals does not adequately describe the polarisation of the large halogen atoms, and a more flexible wavefunction will be needed to calculate the spin resonance constants for these ions.     

Charged and neutral particle multiplicity in π−p and π−n interactions at 40 GeV/c

Data on the multiplicity of charged particles and π⁰ mesons in π^?p and π^?n interactions are presented and compared to various models. The average π⁰ multiplicity tends to increase with increasing number of charged particles.     

Observation of a γ transition in the Λ4H hypernucleus

The γ spectra induced by stopped K^? mesons in a ⁷Li target were obtained in coincidence with the accompanying charged pions. A thorough analysis of these spectra indicates that the observed 1.09 MeV line can be ascribed to a γ transition in the ⁴_ΛH hypernucleus.     

p + p → d + π+ p-wave production

The production of p-wave pions in p + p → d + π⁺ is calculated by introducing into the initial wavefunction NΔ configurations consistent with elastic scattering. Reasonable agreement with experiment is obtained without further adjustment. The Galilean term has only a small effect.     

Inclusive production of muon pairs and vector mesons in π−N collisions at momenta 27 and 40 GeV/c

Experimental results on the investigation of inclusive production of muon pairs and vector mesons (J/ψ, ?⁰(ω)) in π^?N collisions at 27 and 40 GeV/c momenta are presented.     

Analysis of the reaction K−p → K−π−π+p at 40 GeV/c

The reaction K^?p → K^?π^?π⁺p has been measured at 25 and 40 GeV/c at the Serpukhov Proton Accelerator. The production cross section at 25 and 40 GeV/c as a function of momentum transfer and Kππ mass is presented, and results of the partial-wave analysis of the Kππ system yielding information about Q(1300), K¹(1400) and L(1770) mesons are discussed.     

The inclusive reactions π+d → π− + anything and π+d → π−π− + anything at 6 and 24 GeV/c

Inclusive production of π^? mesons has been studied with 6 and 24 GeV/cπ⁺ beams interacting in deuterium bubble chambers. The energy dependence of the inclusive spectra is discussed. In comparisons with π⁺p inclusive interactions, we observe that projectile fragmentation is not independent of the nature of the target at 6 GeV/c. Cross sections and ratios of cross sections are presented. Two-particle correlations are found to be similar at both energies.     

Azimuthal Distributions of K + Mesons in Heavy-Ion Collisions

Strange mesons are considered to be sensitive to in-medium modifications. Theory predicts a repulsive K ⁺ N potential and an attractive K ^? N potential in dense matter. A repulsive K ⁺ N potential would repel the K ⁺ mesons from the bulk of the nucleons and therefore cause a preferred out-of-plane emission of K ⁺ mesons at midrapidity and a directed flow opposite to the nucleons at target and projectile rapidity. One of observables to probe in-medium effects is the azimuthal emission pattern of K ⁺ mesons in heavy ion collisions. KaoS collaboration has measured the azimuthal distributions of K ⁺ mesons in Au + Au reactions at 1.5 A GeV and Ni + Ni reactions at 1.93 A GeV. Data show that K ⁺ mesons exhibit a pronounced enhancement at ${\phi = {90}^\circ}$ , i.e. perpendicular to the reaction plane. The data have also been fitted using the first two components of a Fourier series to get the directed flow v ₁ and elliptic flow v ₂. We used the quantum molecular dynamics model based on the covariant kaon dynamics to simulate the Au + Au collisions at 1.5 A GeV and the Ni + Ni collisions at 1.93 A GeV, to analyze the azimuthal distributions of K ⁺ mesons, and to calculate v ₁ and v ₂ of K ⁺ mesons. Calculated results with a repulsive in-medium K ⁺ N potential can reasonably describe the features of KaoS data. This indicates that the azimuthal distribution is one of sensitive probes to extract information on in-medium properties at high densities.     

Inclusive and semi-inclusive production of positive pions and protons in pp interactions at 22.4 GeV/c

New results on the inclusive and semi-inclusive production of π⁺ mesons and protons in the whole phase space are given for about 2.2 · 10⁴ inelastic $\text{p}\text{p}$ interactions at 22.4 GeV/c. A method of statistical separation for spectra of particles of the same charge which are produced in CP-symmetrical reactions is discussed in detail. Experimental data are compared with quark-parton model predictions.     

Nuclear hyperfine splittings for copper monofluoride in the a3Σ+ state

Lines in the (0, 0) band of the a³Σ⁺-X¹Σ⁺ system of CuF have been recorded at Doppler-limited resolution by laser-induced fluorescence. Nuclear hyperfine structure associated with the Cu nucleus is clearly resolved in many rotational lines. The features have been measured and used to determine molecular parameters for ⁶³CuF in the a³Σ⁺ state. The implications of the hyperfine parameters for the electronic wavefunction are discussed and are shown to be consistent with recent theoretical calculations.     

Preexponential factor in variable-range hopping conduction in CuInTe2

We study the temperature dependence of the electrical resistivity in a single crystal of p-type uncompensated CuInTe₂ on the insulating side of the metal-insulator transition down to 0.4 K. We observe a crossover from Mott to Efros-Shklovskii variable-range hopping conduction. In Efros-Shklovskii-type conduction, the resistivity is best described by explicitly including a preexponential temperature dependence according to the general expression ρ=ρ₀T^αexp(T_ES/T)^1/2, with α≠0. A theory based on the resistor network model was developed to derive an explicit relation between α and the decay of the wavefunction of the localized states. A consistent correspondence between the asymptotic extension of the wavefunction and the conduction regime is proposed. The results indicate a new mechanism for a local resistivity maximum in insulators, not involving magnetic effects.     

Parton structure of heavy mesons with variousJ P in QCD

We calculate the moments of heavy quark-parton distribution in heavy flavored (c, b) mesons with variousJ ^P by means of QCD sum rule approach. The results demonstrate that this method allows to distinguish between the structure functions of hadrons with the same quark content and different spin-parity. In particular the leading effect of heavy quark is less in the case ofP-wave mesons (0⁺, 1⁺). This prediction may be tested in the fragmentation of heavy quark into mesons with variousJ ^P.