Resonance Production Cross Section Research Articles

A formation study of [formula omitted] interactions between 1.51 and 2.90 GeV/ c (III). Resonance production

A systematic study of p p and p d resonance production cross sections in non-strange annihilation channels between 1.51 and 2.90 GeV/ c has been completed. The data have been analysed in relation to the three known structures at c.m. N N energies of 2190, 2350 and 2375 MeV. Several resonance intermediate states may have broad maxima near the isopin one 2350 MeV structure. However, more data below 1.6 GeV/ c are required to better describe the background in this region before firm conclusions may be drawn.

Analysis of [formula omitted] resonances produced in [formula omitted] annihilations at 1.2 GeV/c

The analysis of 18 900 V O events is presented, with reference to the production of K K and K Kπ resonances in the three-, four-, five- and six-body final states. It is established that there is a threshold structure in the ( K K) I=1 state which comes entirely from the decay of K Kπ resonances, the D O and E O. The S ∗ and E O are definitely observed. The isospin of the D O is confirmed to be 0, J D O ⩾1 and, under the assumption L D ω =0, J D PC =1 ++. The F 1 is observed in the final state F 1 η O and the analysis of this channel leads to the conclusion that J F 1 PC =1 +− or 2 − In the five-body final state there is some appearance of two-peaks in the D O mas region, but with the present statistics there is no clear evidence for this effect. The cross sections for single and associated resonance production are given.

Production of K ∗ (892) and K ∗ (1420) in the reaction K +d→K πN(N s) at 4.6 GeV/ c

In a bubble-chamber experiment with the CERN 2 m chamber the reactions (i) K +d→K + π −pp, (ii) K +d→K 0 π 0pp, and (iii) K +d→ K 0 π + pn have been studied at a primary K + momentum of 4.6 GeV/ c. There is abundant production of K ∗ (892) in reactions (i), (ii) and (iii), of K ∗0(1420) in reactions (i) and (ii) and of Δ ++ (1236) in reaction (iii). In reaction (i) backward production of K ∗0 (892) is observed. Reaction and resonance-production cross sections are presented and their energy dependence is investigated. Production and decay angular distributions for the resonance bands are analyzed and compared to the results at other energies. In particular the data pertaining to the reaction K + n→ K ∗0 p are compared in some detail with those for the reaction K − p→ K ∗0 (892) n. Finally, the evidence from reaction (i) for the existence of K N resonances other than K ∗ (892) and K ∗ (1420) is discussed.

Cross sections for resonance production in the reaction π±p → p π±π+π− at 16 GeV/ c, as obtained by a maximum likelihood fit : Aachen-Berlin-Bonn-CERN-Heidelberg Collaboration

Cross sections for resonance production in the reactions π ±p → p π ± π + π − at 16 GeV/ c are determined by a maximum likelihood fit, making use of the measurements of all individual events. The reactions are described by a simple parametrization based on an incoherent superposition of amplitudes for quasi two-body and quasi three-body processes and a non-resonant backgroud. In this way the reflections are accounted for in a consistent way. Thus cross sections are obtained for Δ ++, Δ 0, ρ 0 and f 0 production which do not suffer from the uncertainties of background subtraction typical of the usual technique of fitting individual mass distributions.

The production cross section of high-spin resonances in missing mass experiments in the Veneziano model

The generalized Veneziano model is applied to the study of production cross sections of high-spin resonances in missing mass experiments. Explicit calculations for resonances with J⩽21 have been carried out which show that: 1. (i) the production cross section σ decreases rapidly as J increases, the value for J = 20 being merely ∼10 −3 times the values for J = 1; 2. (ii) as a function of s, σ rises slowly from threshold to a maximum, then falls as s further increases. The position of the maximum increases with J (for J = 19, e.g., s max ∼ 100 GeV 2); 3. (iii) the differential cross section dσ dt is almost exponential in t with no dip in the forward direction. Although the results are qualitatively as expected, we have presented graphically in some detail the numerical values in the hope that they may be useful to experimenters planning such experiments.

Search for exotic resonances in K −d interactions at 3 GeV/ c

A systematic search for exotic states produced in K −d interactions at 3 GeV/ c is reported. From the analysis of the mass spectra of strange mesons, non-strange mesons, hyperons with S = −1 and S = −2, upper limits for the production cross sections of exotic resonances may be placed at one or two orders of magnitude smaller than for the production of normal resonances of same strangeness and baryon number.

Study of [formula omitted] annihilation at 2.5 GeV/ c with production of two kaons in final state

Cross sections for final states and resonance production are given and compared to a statistical model proposed by Lamb. Transverse and longitudinal momenta are studied and the Goldhaber effect is tested. Baryon exchange mechanisms appear.

Asymptotic relations between cross sections for the baryon resonance production

The asymptotic equality of the cross sections of crossed inelastic processes with baryon resonance production is proved.