Meson Ratios Research Articles

? 0 and? production in deep inelastic ?-p interactions at 280 GeV/c

Inclusive distributions of ρ0 and ω mesons have been measured in deep inelastic μ-p interactions at 280 GeV/c. A comparison of the ρ0 cross sections with other leptoproduction experiments is presented. The ω results represent the first observation of this inclusive channel in high energy leptoproduction. The ρ0 and ω yields are found to be equal as may be expected from the available density of states in isospin space. This contrasts with spin angular momentum where the vector to pseudoscalar meson ratio is suppressed relative to the available number of spin states.

Comparative study of baryon production in hard and soft processes

The production ratios of baryons and mesons in deep inelastic reactions are compared with the corresponding quantities in soft hadronic interactions. Contrary to general believe these ratios are equal within the experimental uncertainties and show the same dependence on the longitudinal momentum, provided that processes are compared, where a fixed number of valence quarks is common to the initial state and the secondary under consideration, i.e. processes which are equivalent in the sense of quark recombination mechanisms.

Production of charged mesons with large transverse momentum and with an associated lepton pair

The transverse momentum distributions and branching ratios of mesons produced together with a lepton pair are studied in pp and pp collisions. A simple phenomenological formula describing the p T distributions is proposed. The large- p T behaviour of produced mesons can be used to determine the gluon distribution in the proton and to test its Q 2 variation as predicted by QCD. The prediction for the branching ratios are given. They depend on the form of the proton structure function and pion and kaon fragmentation functions at z = 1.

Hadronic fragmentation initiated by pointlike probes

Isotopic ratios of fast mesons produced in the target-fragmentation r\'egion in reactions initiated by pointlike probes should resemble those seen in ordinary hadronic reactions when the probe removes sea partons from the target but should show dramatic changes once the probe knocks out valence partons. We use simple parton-fusion models to predict the shapes and magnitudes of inclusive meson spectra (${\ensuremath{\pi}}^{+}$,${\ensuremath{\pi}}^{\ensuremath{-}}$,${K}^{+}$,${K}^{\ensuremath{-}}$) in the target-fragmentation region of $\ensuremath{\mu}p$, $\ensuremath{\nu}p$, and $\overline{\ensuremath{\nu}}p$ semi-inclusive scattering and in the inclusive production of mesons in association with a massive lepton pair: $\mathrm{pp}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}\mathrm{MX}$ or $p\overline{p}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}\mathrm{MX}$. Our predictions are in agreement with the limited existing data on these reactions and indicate areas where experiments may shed light on the correlated distribution of several partons in the nucleon.

On coulomb capture ratios of negative mesons in chemical compounds

An approach to reproduce the experimental Coulomb capture ratios of negative mesons in chemical compounds is proposed. An essential feature of this approach is the assumption that the decisive role in the capture process is played by not too strongly bound electrons.

Meson electroproduction in deep inelastic scattering and spin effects

Calculations are made of the deep inelastic electroproduction of mesons from polarised targets. Results are given for charged meson ratios ( pi +/ pi - and K+/K-) and their asymmetries, for proton, neutron and deuteron targets.

The non-mesonic to π− mesonic decay ratio and Λ-neutron stimulation fraction for p-shell hypernuclei

Kinematic analysis of simple hypernuclear production reactions has produced a sample of hypernuclei of ΛB, ΛC and ΛN with negligible background, and a much smaller sample of ΛBe. The values of the non-mesonic to π − mesonic ratio Q − for the above samples are 5.5 ± 0.5 and 4.3 ± 1.1, respectively. A sub-sample of 11 ΛB hypernuclei was separated on the basis of production via an excited state of Λ 12C, giving Q − = 4.8 ± 1.1 for Λ 11B. Assuming the Fermi gas model is applicable to nuclei of mass A ≈ 11, two independent means of analysis of the non-mesonic decays give values for the Λ-neutron stimulation fraction n of 0.41 ± 0.09 and 0.34 ± 0.07 for hypernuclei of charge 5 ≦ Z ≦ 7.

Duality and nonlinear SU 3

Dual ideas when applied to the algebraic realisation of nonlinear unitary symmetry predict the F/D ratio for the helicity non-flip A 2BB̄ vertex, and relate a ratio of meson and baryon mass differences to experimental total cross-sections.

Experimental Determination of Branching Ratios of Vector Mesons into Lepton Pairs

Experimental Determination of Branching Ratios of Vector Mesons into Lepton Pairs

The emission of heavy hypernuclei from 800 MeV/c K- interactions in nuclear emulsion

An investigation of secondary interactions from 800 MeV/c K- interactions in nuclear emulsion with very short connecting tracks has been undertaken. It is concluded that they are spallation products carrying a bound λ0-hyperon. The characteristics of these heavy hypernuclei are described and estimates are made of their nonmesonic to mesonic decay ratio and binding energy. Comparison with similar work is made.

μ-Hydrogen molecular ion and collisions between μ-Hydrogen atom and proton, deuteron and H atom

To the order μ/ M, the ratio of meson and proton masses, the following quantities are calculated: (1) the energy of the ground state of the molecular ion (p− μ−p) +; (2) the square of the meson wave function at the position of a proton in (p− μ−p) +, (3) the “vibrational” level of (p− μ−p) +. The theory of direct and exchange collisions (p− μ)+d → (p− μ)+d, (p− μ)+d → (d− μ)+p is given in terms of the coupling between the meson and nucleon motions. These cross-sections and that of the elastic scattering (p− μ)+p are calculated for energies corresponding to the temperature of liquid hydrogen. Also the cross-section of the (p− μ−p) + formation process (p− μ)+H → (p− μ−p) ++e is calculated, leading to a value ≈ 1/18 for the relative chance of a μ-meson being found in the atomic (p− μ) system and in the molecular system (p− μ−p) + in liquid hydrogen. This, together with (2), leads to the relative probability of ≈ 6.3 of a μ-meson being captured by a proton in the molecular and the atomic state, if μ-capture in the hyperfine state F = 0 only (corresponding to an interaction V—A for the capture process) is assumed.

Spin-orbit potential in pseudoscalar theory

The Levy-Klein method is used to calculate, for pseudoscalar coupling, the spin-orbit potential between two nucleons. The results, carried to two lowest orders in the ratio of meson to nucleon mass, indicate an attractive force for the isotopic spin triplet state and a smaller repulsive force for the singlet state. Quantitative agreement with phenomenological potentials depends, however, on the pair-suppression effects which are still uncertain.

Scintillation Spectrometer Study of Cosmic Radiation at Great Depths

A scintillation spectrometer has been used to observe cosmic-ray events at depths down to 10 000 feet in an oil well. The observed intensity-depth relationship can be explained in terms of the $\ensuremath{\mu}$-meson component and associated showers. The shower to $\ensuremath{\mu}$-meson ratio increases by a factor of 4 in going from sea level to a depth of 1000 meters water equivalent.