Cross sections of annihilation and inelastic final states for pp interactions at 9.1 GeV/c

Topological and channel cross sections are given for annihilation and inelastic final states produced in $\text{p}\text{p}$ interactions at 9.1 GeV/c. Cross sections for prominent resonances in specific channels and charged pion, ?⁰ and Δ⁺⁺ inclusive cross sections are also presented.     

General features of the pp interaction at 12 GeV/c

Simple inclusive cross sections for $\text{p}\text{p}$ interactions at 12 GeV/c are given. The data cover prong cross sections, V⁰ production and resonances. Separation has been made into annihilation and non-annihilation modes. Some implications of the data are discussed. It is pointed out that the ratios of cross sections for $\text{?}{}^0\text{π}{}^{\mathrm{?}}$ production are independent of incident antiproton momentum in $\text{p}\text{p}$ annihilation processes, and that data at the highest available pp energies (ISR) tend to the same value.     

Effective range analysis of low-energy nucleon-antinucleon interaction

An effective range expansion is developed for the N$\text{N}$ system incorporating annihilation, charge-exchange and Coulomb interaction. By fitting the LEAR data on elastic scattering and charge-exchange differential cross sections the N$\text{N}$ scattering lengths and effective ranges are obtained. These solutions reproduce also the data on antiprotonic hydrogen, antineutron-proton total and annihilation cross sections and the behavior of the forward amplitude real-to-imaginary ratio.     

Statistical model cross sections for overlapping resonances

The cross section for a reaction dominated by numerous incoherent resonances is studied, as a function of the average resonance width $\text{Λ}$ divided by the spacing D. Both the Bohr and Wheeler formulae for the average cross sections, and the standard Ericson analysis of fluctuations, are found to be valid only for weakly overlapping resonances, $\text{Λ}\text{D}\text{?}\text{n}\text{2π}$, where n is the number of open scattering channels. Two different models are presented which respect unitarity whatever the resonance widths, namely a K-matrix or Weisskopf-Wigner model, and an eikonal type model. The cross sections are found to saturate either the elastic or the inelastic unitarity bound for strongly overlapping resonances, $\text{Λ}\text{D}\text{?}\text{n}\text{2π}$; and the fluctuations in the cross sections are found to have a coherence length of order nD, rather than $\text{Λ}$.     

Nucleon-antinucleon resonances near threshold: A possible explanation of the S(1930) meson

We suggest a dynamical mechanism (dominance of isoscalar meson exchange) which leads to an interpretation of the S(1930) meson in terms of a doublet of $\text{N}$N resonances with J^πC(I^G)=2^?+(0⁺, 1^?). The presence of a doublet implies constructive interference in the $\text{p}$p → $\text{p}$p elastic channel and destructive interference in the $\text{p}$p → $\text{n}$n channel, in agreement with recent experimental evidence. Possible spin and isospin assignments are suggested for other structures seen in $\text{N}$N cross sections near threshold.     

Resonances due to annihilation in the NN system

We calculate the parameters of the s-wave N$\text{N}$ resonances taking into account boson exchanges and annihilation explicitly in the many-channel N/D method. Two main results are: (1) the width of the usual barionium (quasinuclear) states is sensitive to an effective pionic space and might be as small as ～ 10 MeV. (2) a new kind of resonances appear near the N$\text{N}$ threshold which do not exist without annihilation.     

Study of the D(1285) and E(1420) resonances produced in pp annihilations at 700–760 MeV/c

In this paper we have investigated the properties of the D(1285) and E(1420) meson resonances using the five-body annihilation channels $\text{p}\text{p}\text{→}\text{K}\text{K}\text{πππ}$ obtained in a large statistics experiment (28 events/μb). The analysis favours the 1⁺ spin-parity assignment for the D(1285) meson. The dominant decay mode of the D(1285) into $\text{K}\text{K}\text{π}$ is found to be δ(970)π. The situation concerning the E(1420) meson remains confused although not inconsistent with previous analyses. Partial cross sections on resonance production are also presented.     

Three body resonances in a coupled channel ND approach

Assuming a three body channel to be dominated by the formation of bound states and resonances, the three body problem is reduced to an effective two body coupled channel problem in which pairs of particles, either bound states or resonances, scatter from the remaining third particle. We treat this effective two body problem by the partial wave matrix $\text{N}\text{D}$ method. We study in particular a coupled two channel problem, one channel consisting of one resonance plus one particle, the other of one bound state plus one particle. Our main purpose is to investigate in a full coupled channel situation the possible generation of three particle resonances. With single particle exchange forces forming the dynamical input to the $\text{N}\text{D}$ integral equations, enhancements are generated in a spinless model which correspond to three-particle resonances. The model is then applied, with spin included, to the $\text{p + p +}{}^{12}\text{C}$ system at low energy, in which ($\text{p +}{}^{12}\text{C}$) can form either the bound state ¹³N (G.S.) or the resonance ¹³N¹ (1.944 Mev); the two channels are then $\text{p +}{}^{13}\text{N(G.S.)}$ and $\text{p +}{}^{13}\text{N}{}^1$. The p-p interaction is neglected. It is found that the main effect in this case is the force arising from the coupling of the channels, which is sufficiently strong to generate a three particle level in the composite system ¹⁴O.     

Finite energy bounds for πN scattering

Upper bounds on energy averaged πN cross sections are given. Using low energy data and data from πN backward scattering and $\text{N}\text{N}\text{→ ππ}$ annihilation, we get typically σ_tot ? 80 mb and σ_inel ? 30 mb, for energies just above the phase-shift region. Our bounds are based on assumptions similar to those underlying Froissart's bound and are equal to it asymptotically. However, at finite but large energies, they increase much slower than what might have been anticipated on purely numerological grounds. Related problems in pp and Kp scattering are also discussed.     

Antiproton-neutron interactions at 100 GeV/c

From an exposure of the 30-inch deuterium filled bubble chamber to a 100 GeV/c antiproton-enriched beam at FNAL, we have calculated the topological cross sections for antiproton-neutron interactions with three or more charged particles in the final state. A comparison of our data with pn data at the same momentum allows us to estimate the annihilation contribution to each multiplicity, and hence calculate the average value, and width, of the annihilation multiplicity distribution. Our results are consistent with those from $\text{p}\text{p}$ data at 100 GeV/c, but depart from the trend of lower-energy $\text{p}\text{p}$ data.     

Electronic-excitation transfer collisions in flames—V. Cross sections for quenching and doublet-mixing of K(42P)-doublet by N2, O2, H2 and H2O

Weighted average cross sections for quenching of the K(4²P)-doublet by N₂, H₂, O₂ and H₂O, measured in flames, show no significant temperature dependence in the range from 1500 to 2500K. Doublet mixing cross sections for K(4²P$\text{3}\text{2}$?4²P$\text{1}\text{2}$) transitions were measured at 1720K for N₂, O₂, H₂O. The ratios of both mixing cross sections were measured independently and were found to agree with the detailed balance condition within 2 per cent. It is shown that an ionic intermediate-state model cannot explain the large magnitude of N_2? mixing cross sections.     

On duality in e+e- annihilation

With the help of a relativistic generalization of a formula for the leptonic width of quarkonium in the quasiclassical approximation it is shown that the sum of a sufficiently large number of total cross sections for the production of the quarkonium state (Q$\text{Q}$)_n in e⁺e^- annihilation is equal to the total cross section for production of a quasi-free quark- antiquark pair Q$\text{Q}$.     

Off-shell NN annihilation studied in π+p interactions at 8 and 16 GeV/c

Interactions in which the baryon is emitted forwards in the c.m.s. are studied in 8 and 16 GeV/cπ⁺p collisions. These interactions are interpreted as representing baryon exchange. The properties of such off-shell $\text{N}$N annihilation events are studied. It is found that the multiplicity distribution of the multi-pion system as a function of the effective mass for events with |u_pp| < 1 GeV² is the same as for real $\text{N}\text{N}$ annihilations.     

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.     

Search for narrow resonances in e+e− annihilation at c.m. energies between 33.0 and 36.72

A search for narrow resonances in e⁺e^? annihilation between 33.00 and 36.72 GeV is reported. No evidence is found for the existence of such states. The 90% confidence upper limit on the integrated resonance cross section is determined to be 28 nb MeV, a value significantly below that expected for the lowest t$\text{t}$ bound state.     

The total hadronic cross section for e+e− annihilation between 3.1 and 4.8 GeV center of mass energy

Using the solenoidal magnetic detector PLUTO, we have measured the total cross section for e⁺e^? annihilation into hadrons. Results are presented for center of mass energies between 3.6 and 4.8 GeV, and in the regions of the $\text{J}\text{ψ}$(3.1) and ψ(3.7) resonances. We also present results for the 2 prong cross section in the energy range 3.6 to 4.8 GeV.     

Charged pion production in e+e− annihilation at 14, 22 and 34 GeV CM energy

The inclusive production of π^± mesons in e⁺e^? annihilation has been measured at c.m. energies of 14, 22 and 34 GeV for pion momenta between 0.3 ans 10 GeV/c. The fraction of pions among the charged hadrons is above 90% at 0.4 GeV/c and decreases to about 50% at high momenta. The scaled cross sections ($\text{s}\text{β}$) $\text{d}\text{σ}\text{d}\text{x}$ at 14, 22 and 34 GeV as well as the 5.2 GeV data from DASP have a rather similar x dependence. After integration over the x range from 0.2 to 0.6 the cross sections indicate a monotonic decrease with increasing centre-of-mass energy.     

High resolution proton scattering from 42Ca

Differential cross sections were measured for ⁴²Ca(p, p) at four angles between E_p = 1.2 and 3.0 MeV, with an overall energy resolution of 325 eV. Spins, parities and proton widths were extracted for 170 resonances. Two analogue states were identified and spectroscopic factors determined. The nearest neighbor spacing distributions were analyzed. Proton strength functions were determined for $\text{1}\text{2}$⁺, $\text{1}\text{2}$^? and $\text{3}\text{2}$^? resonances.     

Some information from nucleon-antinucleon annihilation at rest: e+e− annihilation,hadronic fragmentation and deep inelastic structure functions

The experimental spectra of charged pions in $\text{N}\text{N}$ annihilation at rest are described in a model of quasi-two-body decays. The same model predicts the π⁰, ? and ω spectra. We apply a previous calculation to determine in the vector-dominance model, the pions spectra in e⁺e^? annihilation at the same energy. The $\text{N}\text{N}$ system is then used as a heavy hadron in order to describe, in a model-independent way: (i) the projectile fragmentation part in inclusive reactions; (ii) the valence part of the deep inelastic structure function.     

QCD predictions for beauty production in π p and pp collisions

The total cross sections for beauty production in πp, pp and $\text{p}$p collisions are calculated within perturbative QCD. It turns out that the cross sections are around several nanobarns at presently available energies. For the future $\text{p}$p colliders, the total cross section reaches several millibarns.