M.N. Kienzle-Focacci

Elastic scattering of π−p, K−p and pp at 25 and 40 GeV/c

Elastic diffraction scattering of π−, K− and pon protons has been measured at 25 and 40 GeV/c at the Serpukhov Proton Accelerator. Differential elastic cross sections and diffraction slopes are presented in the momentum-transfer interval 0.07–0.80 (GeV/c)2 and compared with existing data at lower energies.

A1, A2 and A3 production in π−p→π−π−π+p at 25 and 40 GeV/c

A sample of ∼ 70 000 fitted events of the reaction of π−p→π−π−π+p at 25 and 40 GeV/c has been obtained with the CERN-IHEP boson spectrometer at the Serpukhov accelerator. A partial-wave analysis shows that (i) A1 and A3 cannot be described by a Breit-Wigner amplitude, (ii) the A2 can be well described by a Breit-Wigner amplitude, (iii) although A1, A3 and A2 have different properties, the energy dependence of their production cross section is similar.

Elastic scattering of pi- p, K- p and anti-p p at 25-GeV/c and 40-GeV/c

Elastic diffraction scattering of π−, K− and pon protons has been measured at 25 and 40 GeV/c at the Serpukhov Proton Accelerator. Differential elastic cross sections and diffraction slopes are presented in the momentum-transfer interval 0.07–0.80 (GeV/c)2 and compared with existing data at lower energies.

The reaction π−p → π−π−π+p at 25 and 40 GeV/c

The reaction pp→pπ−π+p has been studied at 25 and 40 GeV/c at the Serpukhov proton synchroton using the CERN-IHEP spectrometer. The differential cross section has been determined as a function of four-momentum transfer to the proton (0.05–0.30 (GeV/c)2) and pππ mass (up to 2.2 and 2.6 GeV/c2). At both energies there is a broad low-mass maximum with an enhancement at 1.6–1.8 GeV/c2. The cross section in a given mass band falls rapidly with |t|, with an exponential slope that decreases with increasing mass. In both the background and the 1.7 GeV/c2 peak there is a strong Δ−−π+ component. Possible spin-parity (JP) contributions to it are discussed. Throughout the range 1.5–2.2 GeV there is at least one state of J ⩾ 32 and there is interference between states of opposite P, |ΔJ| ⩽ 1. At the peak there is a J ⩾ 52 component. There are striking parallels between this reaction and the boson reactions π−p→π−π−π+p and K− → K−π−π+p.

Analysis of the reaction K−p → K− π−π+p at 40 GeV/c

Abstract The reaction K − p → K − π − π + p has been measured at 25 and 40 GeV/ c at the Serpukhov Proton Accelerator. The production cross section at 25 and 40 GeV/ c as a function of momentum transfer and K ππ mass is presented, and results of the partial-wave analysis of the K ππ system yielding information about Q(1300), K ∗ (1400) and L(1770) mesons are discussed.

Systematic study of Kπ production in the reaction K±p→KS0π±p: technique and measurements at 10 GeV/c

Abstract A two-arm spectrometer for simple event topologies is described. Its main characteristics are: (i) large solid-angle acceptance for the forward emitted particles, owing to the absence of magnetic-momentum analysis; (ii) high-resolution time-of-flight measurement of the recoil proton, in the momentum-transfer range 0.05 t | c ) 2 ; (iii) high data-taking rate and on-line pattern recognition. The apparatus has been used for a systematic study of the Kπ system produced in the reaction K ± p→K S 0 π ± p at 10 GeV/ c . We present the results in terms if spherical harmonic moments of the Kπ decay angular distribution.

Differential cross sections and scaling in π−p → X−p at 25 and 40 GeV/c

Abstract The reaction π − p → X − p has been investigated at p inc = 25 and 40 GeV/ c at the Serpukhov accelerator. Here we present the differential inelastic cross sections Δ 2 σ / ΔtΔM 2 as a function of s , t , and M 2 (X − ). The scaling hypothesis has been tested.

Production of K∗− (890) and K∗− (1420) in the reaction K−p → (Kπ)−p at 25 and 40 GeV/c

The reaction K−p → XK−p has been measured at 25 and 40 GeV/c at the Serpukhov accelerator using the CERN-IHEP boson spectrometer. At both energies we observe production of the resonances K∗− (890) and K∗− (1420) in the channels K∗− → K0π− and K−π0; the momentum dependence of their production cross sections is found to be σ[K∗− (890)] ∞ pinc−1.48±0.04 and σ [K∗− (1420)] ∞ pinc−0.8±0.2.

The decay channel A2− → ηπ− in the reaction π−p → pπ−π+ π−π° at 40 GeV/c

Abstract We have measured the branching ratio A 2 − → ηπ − A 2 − → ϱπ = 0.22 ± 0.03 (statistical error; systematic error ± 0.02) at 40 GeV/ c . From an analysis of the decay angular distribution we obtain a J P = 2 + wave in a pure | M | = 1 state, produced by natural parity exchange.

Boson states in the reaction π− + p → π− + π− + π+ + p with leading π+ meson at 25 GeV/c

Abstract The reaction π − + p → π − + π − + π + + p at 25 GeV/ c was studied in the mass region M 3 π ⩾ 1.8 GeV with leading π + . The mass spectrum of the π + π − system shows peaks corresponding to the ϱ 0 , f and g 0 resonances and an enhancement around 1.9 GeV. Evidence is presented for a J P = 3 + s-wave g 0 π − state (A 4 ) similar to the ϱ 0 π − (A 1 ) and fπ − (A 3 ) threshold enhancements.