Limits on the couplings of ϱ′ (1300 Me) and rhov;″ (1700 MeV) to the photon and to the (ππ) system

The analysis of the reaction e⁺e^?→π⁺π^? measured at the e⁺e^? colliding beam machine ADONE shows that, if ?′ and ?″ exist, the cross sections compare as follows (taking the ? as the reference point): $\text{σ(}\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→ ? → π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{)}$: σ(e⁺e^? → ?′ → π⁺π^?): σ(e⁺e^? → ?″ → π⁺π^?) = 1: (7 ± 4) × 10^?3: (1 ± 5) × 10^?4. The square of the product of their couplings to the photon (γ_?) and the γγ system (g_?ππ) are derived.     

Electron-positron pair production as a probe of chiral symmetry in a hot QCD plasma

Chiral symmetry in the high-temperature plasma phase of QCD is consistent with at least three qualitatively different quark dispersion relations. The rate for $\text{q}\text{q}\text{→}\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}$, with zero total momentum of the e⁺e^? pair in the plasma rest frame is direct measure of the quark dispersion relation. For the three plausible dispersion relations the rates differ by orders of magnitude when the e⁺e^? invariant mass M < 2T.     

Observation of planar three-jet events in e+e− annihilation and evidence for gluon bremsstrahlung

Topological distributions of charged and neutral hadrons from the reaction e⁺e^? → multihadrons are studied at √s of about 30 GeV. An excess of planar events is observed at a rate which cannot be explained by statistical fluctuations in the standard two-jet process. The planar events, mostly consisting of a slim jet on one side and a broader jet on the other, are shown actually to possess three-jet structure by demonstrating that the broader jet itself consists of two collinear jets in its own rest system. Detailed agreement between data and predictions is obtained if the process $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→q}\text{q}\text{?}\text{g}$ is taken into account. This strongly suggests gluon bremsstrahlung as the origin of the planar three-jet events. By comparison of the data with the qq?g-model we obtain a value for the strong coupling constant of α_S(q² = 0.17 ± 0.04.     

An experimental investigation of the radiative structure decay K+ → e+υγ

The decay K⁺ → e⁺υγ has been investigated. For the structure-dependent part with positive γ-helicity (SD₊) the branching ratio $\text{Γ(}\text{SD}{}_{\mathrm{+}}\text{)}\text{Γ(}\text{K}{}_{\mathrm{\mu 2}}\text{) = (2.33 ± 0.42) × 10}{}^{\mathrm{?5}}$ is obtained from 51 ± 3 events observed in the kinematical region E_e ? 235 MeV, E_γ > 48 MeV and θ_eγ > 140°. For the corresponding part with negative γ-helicity we obtain an upper limit Γ(SD_?)/Γ(SD₊) < 11 (90% CL) from the sample of electrons with energies 220 MeV ? E_e < 230 MeV and with no γ in the backward direction. This upper limit implies that the ratio of structure-dependent axial vector amplitudes lies outside the region $\text{?1.8 < a}{}_{\mathrm{<mtext>K</mtext>}}\text{υ}{}_{\mathrm{<mtext>K</mtext>}}\text{< ?0.54}$.For the decay $\text{K}{}^{\mathrm{+}}\text{→}\text{e}{}^{\mathrm{+}}\text{νν}\text{ν}$ the limit $\text{Γ(}\text{K}{}^{\mathrm{+}}\text{→}\text{e}{}^{\mathrm{+}}\text{νν}\text{ν}\text{)/Γ(}\text{K}{}_{\mathrm{e2}}\text{) < 3.8}$ 90% confidence level) was found.     

Event shapes in e+e− annihilation

We present a complete set of rotationally invariant observables (H_l) which characterizes the ‘shapes’ of final states in e⁺e^? annihilation. They are infrared stable when calculated in QCD perturbation theory. We compare the ‘shapes’ of final states from the processes $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→}\text{q}\text{q}\text{,}\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→}\text{q}\text{q}\text{(}\text{G}\text{)}$ and from the three-gluon decays of heavy vector mesons. We also consider the production and decay of heavy quarks and leptons. Using a realistic model for the development of hadron jets, we find that for c.m. energies above about 10 GeV, these processes may be clearly distinguished by their distributions in the H_l. We indicate how our analysis may be extended to deep inelastic lepton-hadron interactions and hadron-hadron collisions involving large transverse momenta.     

Study of the production of a strange (S = −1) dibaryon in the interactions of K− and π+ on deuterium below 1.5GeV/c

The production of a strange dibaryonic system called H⁺₁ (M = 2.13 GeV/c², S = ?1), has been studied with a missing mass spectrometer, at the CERN Proton Synchrotron, in the reaction K^?d → π^?H⁺₁ and in the line-reversed reaction π⁺d → K⁺H⁺₁ between 0.9 and 1.4 GeV/c.The reactions

$\text{K}{}^{\mathrm{?}}\text{d}\text{→ π}{}^{\mathrm{?}}\text{X}{}^{\mathrm{+}}$

,

$\text{π}{}^{\mathrm{<mtext>d</mtext>}}\text{→}\text{K}{}^{\mathrm{+}}\text{X}{}^{\mathrm{+}}$

,have been studied in a missing mass spectrometer at CERN. The experiment (PS159) is well adapted to search for a signal in the missing mass X⁺ (B = 2, S = ?1) produced in the backward c.m.s. direction, between 2.0 and 2.3 GeV/c². The two reactions have been analysed at three different beam settings: 1.4, 1.06 and 0.92 GeV/c for reaction (1) and 1.4, 1.2 and 1.06 GeV/c for reaction (2).     

Meson pair production in two-photon processes

We investigate the amplitudes $\text{γγ → ππ}\text{and}\text{ππ →}\text{K}\text{K}$ by performing a coupled-channel calculation of the final-state interactions in these processes which play a crucial role in reactions like $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→}\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{ππ (}\text{or K}\text{K}\text{)}$. Among our most interesting results we find that the S¹ effect shows up very clearly in these reactions, and that there is an important enhancement in the I = 0 s-wave amplitudes in a large energy range, from threshold to 1.5 GeV, which leads to the prediction of abundant π⁰π⁰ production in such reactions. We also make some comments on the general treatment of final-state interactions.     

Determining the KS→3π amplitude in pp(OR e+e−)→K0K0

The amplitude ratio 〈3π|T|K_S〉/〈3π|T|K_L〉 can be well determined in e⁺e^? (or low energy $\text{p}\text{p}\text{)→K}{}^{\mathrm{o}}\text{K}{}^{\mathrm{o}}$ from the decay time-distribution when each produced kaon→3π, other unknown parameters of the distribution being obtainable from corresponding observations involving known channels like ππ.     

Two emission systems of BS

Two new systems of emission bands near 2100 and 3100 Å have been produced by a microwave discharge in B₂S₃ vapor. From the known X²Σ⁺ and A²Π_i states of BS, these systems have been assigned as E²Σ⁺ → X²Σ⁺ and E²Σ⁺ → A²Π_i. Constants in cm^?1 for the new state are

$\text{E}{}^2\text{∑}{}^{\mathrm{\pm }}\text{: T}{}_{\mathrm{e}}\text{= 47 929.3, B}{}_{\mathrm{e}}\text{= 0.671 (λ}{}_{\mathrm{e}}\text{= 1.752 A), α}{}_{\mathrm{e}}\text{= 0.008}$

,     

Charmed meson decays and right-handed currents

In the presence of right-handed currents including $\text{(}\text{c}\text{s}\text{)}{}_{\mathrm{<mtext>R</mtext>}}$, it is emphasized that the dominant parity-violating (-conserving) Hamiltonian for nonleptonic decays of charmed hadrons transforms like $\text{45}\text{+}\text{45}{}^1\text{(}\text{20″ +}\text{84}\text{)}$ of SU(4), and leads to distinctive results especially in D⁺ → K_Sπ⁺, F⁺ → μ⁺ν_μ and D⁰ → K^?e⁺ν_e, etc.     

A new measurement of the (K+ → e+v)(K+ → μ +v) branching ratio

The branching ratio $\text{R = Γ(}\text{K}{}^{\mathrm{+}}\text{→}\text{e}{}^{\mathrm{+}}\text{v)}\text{Γ(}\text{K}{}^{\mathrm{+}}\text{→ μ}{}^{\mathrm{+}}\text{v)}$ has been measured with an improved version of the apparatus described elsewhere. From 404 observed K⁺ → e⁺v decays, R = (2.51 ± 0.15) × 10^?5 was obtained, to be compared with the value predicted for pure axialvector interaction and μ-e-universality, R_theor = 2.57 × 10^?5.     

Semileptonic decays of pseudoscalar particles (M→M′+ℓ+νℓ) and short-distance behaviour of quantum chromodynamics

The form factors which govern the semileptonic decays of pseudoscalar particles (M→M′+?+ν_?) are constrained by the knowledge of the two-point function Π^μν(q) = i ∫ d⁴x e^iqx〈06TV^μ(x) V^ν+ (0)60〉 in the deep euclidean region, where V^μ(x) denotes the vector current responsible for the transition M→M′. We derive the precise constraints from a QCD calculation of Π^μν which includes perturbative contributions to two loops as well as leading non-perturbative contributions. Applications to π_?3, K_?3 and $\text{D}{}^{\mathrm{+}}\text{→}\text{K}{}^0\text{e}{}^{\mathrm{+}}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}$ decays are discussed.     

QED distributions for hard photon emission in e+e− → μ+μ−γ

The hard photon emission in e⁺e^? → μ⁺μ^?γ is investigated to order α³. Formulas for a number of distributions are obtained, when neglecting terms of order (m_e/?)² and (m_μ/?)². Both charge-even and charge-odd contributions are calculated. The total contribution to the charge asymmetry parameter

$\text{? =}\text{[}\text{d}\text{σ(θ)}\text{d}\text{O}{}_{\mathrm{\mu }}{}^{\mathrm{+}}\text{?}\text{d}\text{Oσ(π?θ)}\text{d}\text{O}{}_{\mathrm{\mu }}{}^{\mathrm{+}}\text{]}\text{[}\text{d}\text{σ(θ)}\text{d}\text{O}{}_{\mathrm{\mu }}{}^{\mathrm{+}}\text{+}\text{d}\text{σ(π ? σ)}\text{d}\text{O}{}_{\mathrm{\mu }}{}^{\mathrm{+}}\text{]}$

does not exceed 5% for the c.m.s. energy 2? = 3 GeV.     

Positron production by muon neutrinos BEBC filled with a neon-hydrogen mixture

For e⁺ energy > 0.3 GeV and 10 GeV < visible energy < 100 GeV we find that: (i) $\text{? = (v}{}_{\mathrm{\mu }}\text{+}\text{Ne}\text{→ μ}{}^{\mathrm{?}}\text{e}{}^{\mathrm{+}}\text{)/(v}{}_{\mathrm{\mu }}\text{+}\text{Ne}\text{→ μ}{}^{\mathrm{?}}\text{) = (0.41 ± 0.15)\%}$; (ii) 1.2 ± 0.5 neutral strange particles are produced per μ^?e⁺ event; (iii) the lifetime of possible positron-parent particles is < 3 × 10^?10 s (90% C.L.); (iv) the cross section for direct e⁺ production via the neutral current is < 0.2 times that via the charged current (90% C.L.); (v) the cross section for producing heavy leptons, L⁺, decaying into e⁺ … is < 0.7 × 10^?3 times that for μ^?production, implying M(L⁺) > 10 GeV.     

Calculation of the γγ → ϱ0ϱ0 cross section at high energies

The processes with the cross sections not decreasing with energy become important at high energies. The simplest processes of this kind are γγ → V_i⁰V_j⁰ where V⁰ = ?⁰, ω, ?, ….. We calculate their cross sections in the high-energy small angle region s ? |t| ? μ². The cross section γγ → ?⁰?⁰ at high energies (s ? 10 GeV²) exceeds those of γγ → ππ, ?⁺?^? considerably. At $\text{s ? 10}{}^4\text{GeV}{}^2$ (this is the characteristic energy for the VLEPP and SLC colliders) and $\text{|t| ? 2}\text{GeV}{}^2$, the ratio $\text{(}\text{d}\text{σ/}\text{d}\text{t)(γγ → ?}{}^0\text{?}{}^0\text{)/(}\text{d}\text{σ/}\text{d}\text{t)(γγ → μ}{}^{\mathrm{+}}\text{μ}{}^{\mathrm{?}}\text{) ? 70}$.     

The emission spectra of H35Cl+, H37Cl+, D35Cl+, and D37Cl+ in the region 2700–4100 Å

The $\text{A}{}^2\text{Σ}{}^{\mathrm{+}}\text{-X}{}^2\text{Π}$ emission spectrum of HCl⁺ has been measured and analyzed for four isotopic combinations. These analyses extend previous work and provide rotational constants for the v = 0–2 levels of the ground state and for the v = 0–9 levels of the excited state. RKR potentials have been determined for both states, although the upper state could not be fitted precisely to such a model. Calculated relative intensities based on these potentials demonstrated that the electronic transition moment must change rapidly with lower state vibrational quantum number. Although considerable caution should be exercised in applying the concept of equilibrium constants to the $\text{A}{}^2\text{Σ}{}^{\mathrm{+}}$ state, the following are the best estimates of these constants (in cm^?1) for the $\text{X}{}^2\text{Π}$ state of H³⁵Cl⁺: B_e = 9.9406, ω_e = 2673.7, A_e = ? 643.7, and $\text{r}{}_{\mathrm{e}}\text{= 1.315}\text{A}\text{?}$. For the $\text{A}{}^2\text{Σ}{}^{\mathrm{+}}$ state of H³⁵Cl: T_e = 28 628.08, B_e ～ 7.505, ω_e ～ 1606.5, and $\text{r}{}_{\mathrm{e}}\text{= 1.514}\text{A}\text{?}$.     

Remark on the production cross section of J particles in hadron-hadron collisions according to the statistical bootstrap model

Heavy J particles decaying into e⁺e^? were recently found in p-Be collisions [1] as well as in e⁺e^? annihilations [2, 3], where also the decay into hadrons with a branching ratio of about $\text{σ(}\text{J}\text{→}\text{h}\text{)}\text{σ(}\text{J}\text{→}\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{) = 15}$ was observed.     

Electromagnetic annihilation of e+e− into quarkonium states with even charge conjugation

We calculate the production of narrow resonances with even charge conjugation ${}^3\text{P}{}_{\mathrm{J}}\text{=1,2}$ in e⁺e^? annihilation in the quarkonium and vectordominance models. We give unitarity bounds for $\text{Γ(}{}^3\text{P}{}_{\mathrm{J}}\text{→ e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{)}$ in terms of $\text{Γ(}{}^3\text{P}{}_{\mathrm{J}}\text{→ γγ)}$ and $\text{Γ(}{}^3\text{P}{}_{\mathrm{J}}\text{→ e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{)}$. The electromagnetic production dominates through the neutral current at low energies independent of details of the model. For masses above 10 GeV the situation is reversed.