A. Dwurazny

Diffractive Production of Strange Mesons at 63-{GeV}

Abstract Nearly 200 000 examples of the diffractive process K − p → K − π − π + p at 63 GeV have been obtained using a two magnet spectrometer equipped with Cerenkov counters for secondary particle identification. In addition some 2000 examples of the process K − p → ω K − p have been obtained. The K ππ data have been subjected to partial-wave analysis. The dominant J P = 1 + system couples to K ∗ π , in both S and D waves, ϱ K, κπ and e K. The data confirm the existence of two J P = 1 + Q mesons and their masses, widths and branching ratios are given. The ifωK data show that the couplings of the Q mesons to ω K are approximately equal to the couplings to ϱ 0 K. The two 1 + nonets expected in the quark model are discussed in the light of this and other recent experiments. There is strong evidence for a broad J P = 0 − resonance at about 1.46 GeV. At higher masses, structure in the J P = 2 − partial waves establishes the existence of at least one J P = 2 − L meson.

Diffractive production of 3π states at 63 and 94 GeV

Diffractive production of the 3π system has been studied at 63 and 94 GeV using a two magnet spectrometer with high, uniform acceptance. The total number of events used in the analysis is ∼600 000. The A2 meson is shown to be diffractively produced. The existence of a resonant component in both the 1+ and 2− enhancements is established and resonance parameters for the corresponding A1 and A3 mesons are given. There are several indications in the data of states which would correspond to radial excitations in the quark model.

Inclusive φ-meson production in 93 and 63 GeV hadron interactions

Abstract The inclusive reactions h+p→φ+X, (h=π±,,K±,p±), are studied for 0⪅xF⪅0.3 and p⊥ ⩽ 1 GeV at 93 and and 63 GeV incident momentum. Differential cross sections dσ/dp⊥2 anddσ/dxF are presented and are compared with predictions of the naive parton model.

Experimental proof of the existence of the A1 meson

Abstract In partial wave analyses of the ( π − π − π + ) system, substantial shape changes of the 1 + S ( ϱπ ) intensity as a function of t , and relative phase changes of ≈ 90°, provide compelling evidence for a resonant A 1 of mass ≈ 1280 MeV and width ≈ 300 MeV.

3π resonances in 2− partial waves

Abstract The J PC = 2 −+ partial wave intensities and their large phase changes prove the resonant nature of the A 3 meson (mass ≈ 1670 MeV, width ≈ 210 MeV). The decay modes are f 0 π , ϱ 0 π , and ϵ 0 π . Evidence is found for a further 2 − enhancement.

Observation of a narrow pp enhancement at 1940 MeV

Abstract A narrow enhancement is observed in p p states produced inclusively in proton-proton interactions at 93 GeV. The mass 1940 ± 1 MeV is consistent with that of the S(1936).

A silicon strip detector telescope for the measurement of production and decay of charmed particles

Abstract A silicon detector telescope with 5 μm spatial resolution has been developed and successfully used to select charmed particles produced in high energy hadron collisions. A brief review of the properties and the performance of the system is given.

Production and decay properties of D and D∗ mesons in π−Be interactions

Abstract D ∗± , D ± , D 0 , and D 0 production has been observed in π −Be interactions at 120, 175, and 200 GeV. The dependence of the D cross section on transverse and longitudinal momentum is presented. The ratio of D∗ to D and charged to neutral D production is determined. Leading particle effects in D production are investigated. Relative branching ratios for several D decay modes are evaluated. A limit on D 0 − D 0 mixing is given.

Observation of D∗± and production in high-energy π−Be interactions at the SPS

Abstract An experiment has been performed to search for associated hadronic production of charmed mesons, using a large-aperture forward magnetic spectrometer setup in a π− beam at the CERN SPS. A prompt electron trigger was used to select events containing a pair by charmed particles. D mesons have been identified by reconstruction of hadronic decay modes such as Kπ, Kππ. Data have been taken at 120, 175, and 200 GeV, The D D cross section measured at 175 200 GeV is σ( D D ) = (48 ± 15) μ b with a systematic uncertainty of ±50%. The energy dependence of the cross section is measured to be σ( D D ) [120 GeV )/σ( D D [175/200 GeV ] = 0.62 ± 0.34 .

Evidence for the associated production of strange particles and φ mesons

Abstract Results are presented of an experiment studying inclusive ∅-meson production off protons by hadrons of 93 and 63 GeV incident momentum. Evidence is found for an enhanced probability of observing additional strange particles when the final state contains a ∅ meson. This supports the assumption that central production of ∅ mesons proceeds, for a significant part, by the OZI allowed fusion of strange quarks.