Asymptotic freedom,light quarks and the origin of the ΔT = 12 rule in the non-leptonic decays of strange particles

A dynamical mechanism for the $\text{ΔT =}\text{1}\text{2}$ rule in the non-leptonic decays of strange particles is considered. The weak interactions are described within the Weinberg-Salam model while the strong interactions are assumed to be mediated by the exchange of an octet of colour vector gluons. It is shown that the effect of the strong interactions gives rise to new operators in the effective Hamiltonian of weak interactions which contain both left- and right-handed fermions. These operators satisfy the $\text{ΔT =}\text{1}\text{2}$ rule, and estimates within the relativistic quark model indicate that their contribution dominates the physical amplitudes of the K → 2π, 3π decays.     

The possibility of new fermions with ΔI = 0 mass

In the Glashow-Weinberg-Salam model the fermions have $\text{ΔI =}\text{1}\text{2}$ masses from the breaking of the weak SU(2) gauge symmetry. In many enlarged models, such as those from grand unified and/or supersymmetric theories, there are additional fermions with undetermined ΔI = 0 (SU(2) invariant) masses. We study these new fermions. They induce flavour changing neutral currents. We show that the mixing angles of ΔI = 0 fermions of mass order M with normal $\text{ΔI =}\text{1}\text{2}$ fermions of mass order m ? M are order η or η², where η = m/M. If M > 150 δ, δ being a model-dependent mixing parameter of order a normal fermion mass, the amplitudes of all FCNC processes are below the experimental sizes and limits. Thus for δ?0.1 GeV, M can be as low as 20 GeV, close to the present experimental lower bound. δ is fixed, and less than 0.1 GeV for all relevant cases, if we assume the mass hierarchy of the known fermions is not the result of a particular choice of ΔI = 0 mass parameters. If produced ΔI = 0 mass fermions will be noticeable by the mass degeneracy within their isospin multiplets. There will be an enhanced ratio of neutral to charged decays over the normal fermions. Standard GUT predictions are changed little.     

Study of inclusive neutral current interactions of neutrinos and antineutrinos

We report on results from a study of hadron-energy distributions for ν and $\text{ν}$ inclusive neutral current interactions. There is no significant variation of the neutral to charged current total cross-section ratios R_ν and $\text{R}\text{ν}$ with neutrino energy. The space-time structure of neutral currents is dominated by V?A, with a significant admixture of V+A. The Weinberg-Salam model is in agreement with all data if sin²θ_w=0.24±0.02.     

Thermal changes in the optical properties of SnSxSe2−x crystals

Optical measurements on crystals in the series SnS_xSe_2?x for 0 ? x ? 2, have yielded information on the changes in the ordinary refractive index $\text{Δn}\text{ΔT}$ and the energy gap $\text{ΔEg}\text{ΔT}$ in the temperature range 125–425 K. The coefficient $\text{Δn}\text{ΔT}$ has values +40 to +160 × 10^?6K^?1 and this confirms that covalent bonding predominantly exists in these materials. The coefficient $\text{ΔEg}\text{ΔT}$ remains fairly consistent for all values of x with an average value of -8.0×10^-4eV K^-1.     

Electrical properties of metal-piezoelectric semiconductor interface under stress

The effects of the mechanical stress on the current-voltage characteristics of metal-piezoelectric semiconductor interface are investigated for both AuCdS and AuGaP Schottky diodes. The changes in currents due to the approximately uniaxial stress, which is applied by bending the crystal wafers attached to the cantilever, are measured. Under the compressive stress parallel to the interface, the current of the diode fabricated on the (0001)Cd or that on the $\text{(}\text{1}\text{?}\text{1}\text{?}\text{1}\text{?}\text{)P}$ surface increases but that of the diode on the $\text{(000}\text{1}\text{?}\text{)S}$ or on the (111)Ga surface decreases. The direction of the changes in current is opposite under the tensile stress. The relative current change $\text{ΔI}\text{I}{}_0$ is proportional to the applied stress and its magnitude at the surface strain 3 × 10^?4is 2.4 × 10^?2, 8.0 × 10^?2, 1.0 × 10^?2 and $\text{0.5 × 10}{}^{\mathrm{?2}}\text{for diodes made on (0001)Cd, (000}\text{1}\text{?}\text{)S, (111)Ga}$ and $\text{(}\text{1}\text{?}\text{1}\text{?}\text{1}\text{?}\text{)P}$ surfaces respectively. These values are also nearly constant over the small bias region in which I₀ is proportional to exp($\text{eV}{}_{\mathrm{a}}\text{KT}$). In this region, the changes in current are transformed to the changes in barrier height. In order to explain this effect, the changes in barrier height are calculated according to the piezoelectricity in the depletion layer of the Schottky diodes. The predicted value agrees with the one obtained experimentally.     

Weinberg-Salam model with two Higgs doublets and the ΔI = 12 rule

It is suggested that the modification in the Higgs sector of the Weinberg-Salam model which is required by CP violation, also provides an explanation for the $\text{ΔI =}\text{1}\text{2}$ enhancement in the non-leptonic decays of strange particles.     

Spin selectivity of the polarised (d, 2p) reaction

Tensor polarisation observables in intermediate energy $\text{(}\text{d}\text{, 2}\text{p}\text{)}$ charge exchange on 0⁺ nuclei are investigated. It is shown that for small excitation energies of the di-proton the polarisation can help to distinguish between 0^?, 1^? and 2^? final nuclear states produced through ΔL = 1, ΔS = 1 transitions. The information to be obtained is similar to that inherent in $\text{(}\text{p}\text{,}\text{n}\text{)}$ spin transfer experiments but the deutron-induced experiments should have much higher efficiency.     

A folded diagram microscopic calculation of nuclear Coulomb displacement energies

We have performed a rather extensive microscopic calculation of the ¹⁷F-¹⁷O Coulomb energy differences ΔE_C. Our main purpose has been to study the effects of (i) folded diagrams, (ii) core polarization and (iii) the effects due to different nucleon-nucleon potentials, different single-particle spectra and different radial wave functions. Using a proton-neutron representation we have included higher-order Coulomb corrections like e.g. the coupling of valence particles to collective vibrations of the core.The inclusion of folded diagrams is very important; it is equivalent to a self-consistent treatment of the Q-box starting energies. It causes a significant suppression of the effect due to core polarization, its contribution to ΔE_C becoming small, about 0.03 MeV. As a consequence of this “self-correcting” behavior our results for ΔE_C are quite stable with respect to the choice of different single-particle spectra. Two rather different nucleon-nucleon potentials, the Reid soft-core potential and a meson exchange potential of the Bonn-Jülich group also lead to quite similar results for ΔE_C. In the case of $\text{J =}\text{5}\text{2}{}^{\mathrm{+}}$, for example, Δ_C calculated with the Reid potential ranges, depending on other assumptions, from 3.36 to 3.43 MeV and from 3.36 to 3.40 MeV with the Bonn-Jülich potential: Both are significantly smaller than the experimental value of 3.54 MeV. Optimizing the radial wave functions in the spirit of a Brueckner-Hartree-Fock theory improves the calculated values of ΔE_C for the $\text{J =}\text{1}\text{2}{}^{\mathrm{+}}$ state but not for $\text{J =}\text{5}\text{2}{}^{\mathrm{+}}\text{or}\text{3}\text{2}{}^{\mathrm{+}}$.We feel that other processes such as the explicit inclusion of core deformation or mesonic degrees of freedom or both are needed to explain the Coulomb displacement energies.     

Evidence for new meson resonances from the reaction pp → K−K+

The differential cross sections for $\text{p}\text{p}\text{→}\text{K}{}^{\mathrm{?}}\text{K}{}^{\mathrm{+}}$ provide new evidence for mesons with masses between 2.1 and 2.5 GeV/c². The zeros of the cross sections suggest the existence of J^P = 3^? states with both I = 1 and I = 0 at masses between 2.1 and 2.18 GeV/c². The results also support a J^P = 4⁺ state near 2.34 GeV and are consistent with 5^? states in both I = 1 and I = 0 close to 2.5 GeV. This analysis confirms the I = 1 3^?, 5^? and I = 0 4⁺ states seen previously in $\text{p}\text{p}\text{→ π}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}$ and is in agreement with the existing data for the non-annihilation processes.     

Transition amplitudes and probabilities for the Weinberg-Salam model

Transition probabilities for the processes vv?vv, vv?, $\text{vv}$?$\text{vv}$, and spin-dependent transition amplitudes for the processes ve?ve, vē?vē, v?e?v?e, $\text{ve}$?$\text{ve}$ and vv??eē are calculated in lowest order for the Weinberg-Salam model.     

Evidence for a narrow peak in Ksoπ±π+π- at 2.6 gev in 12 gev/cpp interactions

We report the evidence for a narrow charged peak (5.5 s.d.), which we suggest calling the I, in the 6-prong-V⁰ topology of $\text{p}$p interactions at 12 GeV/c. The mass, widht and the product of cross section σ_I times the branching ratio BR into the final state (K_s^oτ±τ⁺τ^? are found to be: $\text{M}{}_{\mathrm{I}}\text{=2.60 ±}\text{0.01}\text{GeV}\text{/}\text{c}{}^2$, $\text{Γ}{}_{\mathrm{I}}\text{?}\text{0.018}\text{GeV}\text{/}\text{c}{}^2$, σ_I·BR≈20 μbarn     

Elastic antiproton-deutron scattering below 1.0 GeV/c

We present differential cross sections for elastic $\text{p}$d scattering at beam momenta 0.735 and 0.940 GeV/c and momentum transfers in the range 0.04<|t|<0.5(GeV/c)². The $\text{p}$d elastic differential cross section is expressed in terms of a deutron form factor and the I=0 t-channel exchange $\text{N}$N amplitudes, enabling us to isolate the corresponding I=0 t-channel exchange cross sections.     

Variational calculations of realistic models of nuclear matter

We report variational calculations of nuclear matter with a semi-realistic Reid v₁₂ model, and a realistic v₁₄ model of the two-nucleon interaction operator. The v₁₄ model fits the available nucleon-nucleon scattering data up to 425 MeV lab energy, and has relatively weak L² and $\text{(}\text{L}\text{·}\text{S}\text{)}{}^2$ interactions in addition to the standard central, tensor and ($\text{L}\text{·}\text{S}$). The L² and $\text{(}\text{L}\text{·}\text{S}\text{)}{}^2$ interactions are treated semiperturbatively; their contribution reduces the overbinding of nuclear matter. However, the equilibrium k_F = 1.7 fm^?1 and E₀ = ?17.5 MeV obtained with the v₁₄ model are both higher than their empirical values k_F = 1.33 fm^? and E₀ = ?16 MeV. We assume that the difference between the calculated and empirical E(ρ) is entirely due to three-nucleon interactions (TNI). The TNI contributions are phenomenologically added to the nuclear matter energy, and their parameters are adjusted to obtain the correct equilibrium energy, density and compressibility. The required TNI contributions appear to be of reasonable magnitude.     

The change of conductivity of erbium films caused by the sorption of hydrogen and oxygen

Films of erbium were evaporated onto the inside wall of a pyrex glass reaction vessel at 1O^?9 torr. Their mean thickness (200–600 Å) was deduced from their mass and geometrical area. Estimates of their surface areas were made from the physical adsorption of krypton at 78 °K (BET method) giving a mean specific surface area of 71 m^?2 g^?1. The number of surface sites was calculated from a relationship given by Brennan et al.¹⁾. The sorption of hydrogen and oxygen was studied separately, by measuring the changes in the electrical resistance of the films as a function of the amount of pure gas admitted to the reaction vessel in measured doses ～ 10¹⁸ atoms per dose. The experiments were repeated at 295 °K, 200 °K, 130–140 °K for both gases (measurements at 78 °K were not reproducible, probably because of a magnetic phase change). Hydrogen at 295 °K [as reported²⁾] caused an initial increase ΔR in the original resistance R to a maximum $\text{ΔR}\text{R}$ ～ 20 %, which was followed by a decrease to $\text{ΔR}\text{R}\text{= 0}$ and then to $\text{ΔR}\text{R}\text{< 0.}$ A similar pattern of resistance changes was observed at 200°K and 130–140°K with smaller changes of $\text{ΔR}\text{R}$, i.e. 16 % and 8 % respectively, but no significant differance in surface (θ) and bulk atomic ratios at which the maxima occurred, e.g. $\text{ΔR}\text{R}$ was a maximum for 1.6?θ?1.9.     

High spin collective excitations in 101Ru

The energy level structure of ¹⁰¹Ru was studied using the reactions ¹⁰⁰Mo(α, 3n)¹⁰¹Ru and ¹⁰⁰Mo(³He, 2n)¹⁰¹Ru. Excitation functions, γγ coincidences and γ-ray angular distributions were measured. Three ΔI = 2 cascades proceeding to a $\text{5}\text{2}{}^{\mathrm{+}}$, $\text{7}\text{2}{}^{\mathrm{+}}$ and $\text{11}\text{2}{}^{\mathrm{?}}$ state were observed. A decay scheme is presented showing energies up to 5849 keV and spins up to $\text{35}\text{2}$. The bands are discussed within the framework of the Nilsson model with Coriolis coupling in which the recoil effect has been properly introduced.     

Study of the reactions K−p → K+K−Λ and K−p → ppΛ, at 10 and 16 GeV/c

The reactions (1) K^?p → K⁺K^?Λ and (2) $\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{p}\text{p}\text{Λ}$ have been studied on samples of 109 and 64 events, respectively, at 10 GeV/c and 125 and 69 events at 16 GeV/c, reasonably free from contaminations. The investigation of the first reaction uses also 84 events of the $\text{K}{}^0\text{K}{}^0\text{Λ}$ final state at 10 GeV/c. Analysis of the Van Hove plots indicates that the K⁺K^?Λ and $\text{p}\text{p}\text{Λ}$ final states are produced by two main mechanisms: (i) a ΔQ = 0 process, with a strong diffractive component near threshold, involving the dissociations p → K⁺Λ in reaction (1) and $\text{K}{}^{\mathrm{?}}\text{→}\text{p}\text{Λ}$ in reaction (2) and (ii) a ΔQ = 1 process involving hypercharge exchange, and producing K⁺K^? and $\text{p}\text{p}$ systems in reactions (1) and (2), respectively, recoiling off the Λ. With increasing energy, this hypercharge exchange process decreases slowly when K⁺K^? is produced, but fast where the production of $\text{p}\text{p}$, violating the Zweig rule, occurs.     

Decomposable operators application to K.M.S. weights in a decomposable von Neumann algebra

Let $\text{U}\text{=}\text{?}\text{⊕}\text{U}\text{(ξ) dμ(ξ)}$be a decomposable von Neumann algebra, ? a faithful strictly semi-finite weight on $\text{U}$, σ^?_! the modular automorphism group associated with ?; if $\text{U}$ admits a cyclic and separating vector (or if π_?($\text{U}$)′ is countably decomposable, (π_?, H_?) being the representation of $\text{U}$, given by ?), then we get $\text{?=}\text{?}\text{⊕}\text{?ξ dμ(ξ)}$ (the ?ξ being faithful strictly semi-finite weights) and $\text{σ}{}^{\mathrm{?}}{}_{\mathrm{!}}\text{=}\text{?}\text{?}\text{σ}{}^{\mathrm{?}}{}_{\mathrm{!}}\text{dμ(ξ)}$ (σ^?_! is the modular automorphism group in $\text{U}$(ξ), associated with ?).These results are obtained by developing the functional calculus for decomposable operators. More precisely, let $\text{Δ=}\text{?}\text{⊕}\text{Δ(ξ)dμ(ξ)}$ be a Hermitian (bounded) decomposable operators, and f a complex essentially bounded function on R; then $\text{f(Δ) =}\text{?}\text{?}\text{f(Δ(ξ))dμ(ξ)}$.Extensions of these results are given for nonessentially bounded measurable fields of bounded operators and for unbounded self-adjoint operators commuting with diagonalizable operators.     

Bound exciton luminescence of Ar- and Al-implanted ZnO

Argon- and aluminum-implanted ZnO single crystals (N_impl=10¹⁶?10¹⁹cm^?3) were investigated at liquid helium temperature by photoluminescence. We obtained highly resolved emission spectra of implanted and thermally annealed samples. Maximum luminescence yield was achieved after annealing with an oxygen ambient at 800°C and an anneal time of 30 min. In Al-implanted ZnO crystals, we observed a strong emission line $\text{I}{}_{\mathrm{<mtext>5</mtext><mtext>6</mtext>}}\text{at λ = 3688}\text{A}\text{?}$. The intensity of this line is correlated with the implanted Al concentration. The I_{$\text{5}\text{6}$} line is interpreted as the recombination of a bound exciton at a polycentric Al complex.     

Study of the Kππ system produced in K−p → KππN reactions at 14.3 GeV/c

We have studied the $\text{K}\text{ππ}$ system in the 14.3 GeV/c reactions K^?p → K^?π⁺π^?p, $\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{K}{}^0\text{π}{}^{\mathrm{?}}\text{π}{}^0\text{and}\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{K}{}^0\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{n}$. The data have been obtained from a 500 000 picture exposure of the CERN 2m HBC. The first two final states are dominated by Q-production in the Kππ system; there is also an L-signal at M (Kππ) ～ 1.75 GeV. The reaction cross sections are compared to K^?p data at other energies. We discuss the Kππ mass dependence of the diffractive production slope. Evidence is presented for a Q^?p versus Q⁺p differential cross section cross-over around |t| = 0.17 GeV². A t-channel isospin analysis for the $\text{KN}\text{→}\text{K}\text{1(890)π}\text{N}$ channels in the Q-region shows that the I = 1 exchange amplitude is $\text{? 10\%}$ of the dominant I = 0 exchange amplitude. The Kππ decay distributions indicate a predominant J^P = 1⁺ state in the Q-region, and an important J^P = 2^? contribution in the L-region. We find neither s-channel nor t-channel helicity conservation at the meson vertex in the Q- or L-regions. The Kπ angular correlation moments within the Kππ diffractive system are characteristic of Kπ elastic scattering, suggesting a π-exchange Deck-type production mechanism. There is evidence for a Kf⁰ and κπ contribution (where κ is the J^P(Kπ) = 0⁺ state) to the diffractive Kππ system. A fit to the $\text{K}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{and}\text{K}{}^0\text{π}{}^{\mathrm{?}}\text{π}{}^0$ Dalitz-plot distributions for the Q-re gion indicates that the ratio of $\text{K}\text{?}\text{to K}{}^1\text{π}$ decay amplitudes decreases with increasing Kππ mass.