H. Tiecke

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).

A2 meson production at high energies in the reaction π−p→π−π−π+p

Abstract The A 2 meson is studied in the decay mode ϱ 0 π − using partial wave analyses of 600 000 events from the reaction π − p→ π − π − π + p at 63 and 94 GeV incident momentum. Common production mechanisms are indicated for this resonance and diffractive 1 + and 2 − components.

Forward particle production in π−p andK−p collisions at 58 GeV/c and comparison with quark models

We present single inclusive π±, π0 andK± spectra in the forward fragmentation region (x>0.2,pT<1.5 GeV/c) as well as correlations between two charged particles. The data were recorded in an unseparated negative hadron beam at the CERN SPS using a large acceptance forward spectrometer. Our maasurements are compared in detail with several models which emphasise the role of the beam valence quarks in this production process. The connection to measurements at largepT is also investigated.

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.

Evidence for a non-\(q\bar q\) tensor meson at 1,410 MeV produced in the reaction π−p→K s 0 K s 0 n at 63 GeV

AbstractWe present an analysis of theKs0Ks0 system produced in the reaction π−p→Ks0Ks0n at 63 GeV based on ∼700 events in the kinematical region of |t|<0.5 GeV2. We concentrate on masses between 1,200 and 1,600 MeV where a double maximum structure is observed. Performing an amplitude analysis in this mass interval we find thatS,D0 andD+ waves contribute to the mass spectrum at approximately equal strength. The peaks are attributed to spin 2 waves. However, we failed to explained them by interferingf(1270),A2(1310) andf′(1520) resonances alone. While the first peak can be associated withf(1270)−A2(1310) production, an additional tensor meson is needed with mass of ∼1410 MeV and a narrow width for a description of the second one. The analysis as well as the energy dependence deduced from some publishedKs0Ks0 mass spectra suggests this object to be dominantly produced by a natural parity exchange. Because the 2++n