Winfried A Mitaroff

Spin-parity analysis of the E meson centrally produced in the reactions π+ p → π+ (K01K±K±) p and pp → p(K01K±π ±)p at 85 GeV/c

Results are presented of a spin-parity analysis on a sample of ∼ 1000 E mesons centrally produced in the reactions (π+/p) p → (π+/p) (K01K±π∓) p at 85 GeV/c. The E quantum numbers are determined to be JPC = 1++. Its decay in this channel is consistent with being 100% into K∗K + c.c. and no evidenceis seen for a δ π decay mode where δ → KK. The mass and width were determined to be M = (1425 ± 2) MeV and Γ = (62 ± 5) MeV.

Evidence for a narrow width boson of mass 2.95 GeV

Abstract In a search for resonances coupled to the p pπ − system, we have studied π − p interactions at 16 GeV/ c giving a forward antiproton, using the Omega spectrometer at CERN. In the final states involving a p , p and π − we observe a 5.6 (6.3) standard deviation enhancement in the p pπ − mass spectrum at (2.95 ± 0.01) GeV with a width consistent with the resolution ( σ = 15 MeV). The production cross section × branching ratio is estimated to be of the order 1 μb. The data are consistent with a resonance decaying partly via intermediate p p final states.

A study of the reaction π−p → φφn AT 16 GeV/c

Abstract The reaction π − p → φφ n has been isolated at 16 GeV/ c and its cross section determined to be 40 ± 10 nb. The φφ mass spectrum shows a threshold enhancement between 2.1 and 2.5 GeV. A successful description of the angular content of the φφ system requires two interferingss J P = 2 + states.

Inclusive φ production in π− p interactions at 16 GeV/c

Abstract Inclusive φ production is studied in π − p collisions at 16 GeV/ c . The φ cross section for Feynman variable x φ > 0.2 is found to be (15.5 ± 3.6) μb. This leads to an extrapolated cross section of (29.9 ± 7.0) μb for x φ > 0.0. Fitting the momentum transfer squared distribution of the φ to the form e −bp 2 T gives an average slope of b = (2.4 ± 0.3) (GeV/ c −2 for x φ > 0.5.

Observation in the K+K− system of a new structure at 2.20 GeV

Abstract A sample of 56 909 events of the reaction π − p→K + K − n at 10 GeV/ c has been measured in the Omega Spectrometer at CERN. In the K + K − system, besides production of mesons in the S ∗ /φ, f 0 / A 2 , g /ω ∗ and h regions we observe a new structure at 2.20 GeV with a width of the order of 200 MeV.

A partial-wave analysis of the (K+K−π−) system produced in π−p → K+K−π−p at 16 GeV/c

The reaction π−p → K+K− π− p at 16 GeV/c was studied in the CERN OMEGA spectrometer and a partial-wave analysis (PWA) of the low-mass (K+K−π−) system (1.3–2.0 GeV) was performed. Only states in the unnatural spin-parity series produced by natural parity exchange are important and they approximately conserve t-channel helicity. The 1+S K∗K wave dominates the low-mass (K+K−π−) region. We observe an enhancement in 2−P K∗K wave at a mass of 1.7 GeV, consistent with the decay of the A3 resonance.

Test of the Zweig rule in π−p interactions at 19 GeV/c

Abstract We have observed φ production in π − p interactions at 19 GeV/ c with (44±10) events in the final state φπ + π − π − p and (45±9) events in φ K + K − π − p. The production ratios φπ + π − π − p/ ωπ + π − π − p ≈ 0.005 and φ K + K − π − p/ ϱ °K + K − π − p ≈ 0.45 agree with Zweig-rule expectations.

Search for glueballs at high pT in 300 GeV/c π−N interactions

Abstract The production of glueball candidates ι and Θ in hadronic interactions is investigated at high transverse momenta. The data come from a sample of π − interactions at 300 GeV/ c on a beryllium target, obtained at the CERN Omega Spectrometer using a trigger and off-line selection requiring a system of charged particles with p T >2 GeV/ c recoiling against an opposite particle with p T >0.9 GeV/ c . Cross sections are given for known resonances (ϱ 0 , φ, f 0 ) and upper limits for the ι(1440) and Θ(1720). A co mparison is made with recent theoretical calculations.

A high statistics search for the ppφ− mass enhancement at 2.95 GeV

Abstract An experiment has been undertaken at the CERN SPS, using the Omega spectrometer, aimed at confirming the enhancement observed in a p p φ − mass spectrum at 2.95 GeV [1]. With statistics of twelve times the original experiment no signal is seen. In the reaction φ − p → p p φ − p , the upper limit (four standard deviations) for the production of a resonance in the p p φ − system at 2.95 GeV, with a width ⩽ 30 MeV, is 50 nb.

Analysis of the reaction π−p→ppn at 10 and 16 GeV/c

Abstract Antiproton-proton pairs and antiproton-neutron pairs produced in the reaction π − p → p pn , were studied in the mass range from threshold to 2.6 GeV on the basis of 4 · 104 events at 10 GeV/c and 2 · 104 events at 16 GeV/c incident momentum. The cross section for peripheral production of p n pairs is significantly larger than for p p pairs. The p p production mechanism is consistent with the predictions of the one-pion exchange model, whereas the p n production cannot be sufficiently described by that model. A partial-wave analysis of the p p system, assuming pure one-pion exchange, shows that we need for a reasonable description of our data in addition to the JP = 3− resonance at 2.11 GeV and the 4+ resonance at 2.26 GeV found in an analysis of a formation experiment ( p p → π + π − ), two further resonances: a 1− state at 1.92 GeV and a 2+ state at 2.02 GeV.