P. F. Loverre

Observation of a narrow hyperon state of mass 3.17 GeV

Abstract We present evidence for a narrow Y∗ with a mass of 3.17 GeV and a width ⩽ 20 MeV decaying to ΣKK + pions, ΛKK + pions and ΞK + pions. The data come from two high statistics K−p bubble chamber experiments with a sensitivity of ≈100 eV/μb at 8.25 GeV/c and ≈ 45 eV/μb at 6.5 GeV/c.

Study of hypercharge exchange reactions of the type 0−1/2+→2+1/2+ at 4GeV/c

AbstractResults are presented for the quasi two-body hypercharge exchange reactions of the type 0−1/2+→2+1/2+:n

Q1 production by hypercharge exchange in π-p interactions at 3.95 GeV/c

begin{gathered} pi ^ - p to K^0 (1420)(Lambda ,sum ^0 ), hfill K^ - p to f^0 (1270)(Lambda ,sum ^0 ), hfill K^ - p to fprime (1515)(Lambda ,sum ^0 ), hfill end{gathered}

Observation of a KK enhancement at 1.85 GeV in the reaction K−p → KKΛ at 8.25 GeV/c

n using data from two high statistics bubble chamber experiments. The total and differential cross sections are presented and compared with those obtained for the corresponding vector meson reactions and with simple phenomenological ideas.

Ξ(1320) and Ξ(1530) production in K−p interactions at 4.2 GeV/c

Abstract Differential cross sections and polarizations are presented for the reactions K − p → Λπ 0 , Λη , Λη ′ at 8.25 GeV/ c incident K − momentum. The data, which come from a high statistics experiment in the CERN 2 m bubble chamber, are compared with previous experimental results on the same reactions and with current theoretical ideas.

Evidence for a Λp resonance with spin-parity 2−

Q-meson production is studied in the hypercharge exchange reaction π-p → (Kππ)Λ at 3.95 GeV/c by selecting events witht(π- →Kππ)>1.2GeV2. An enhancement with a mass of 1294±10 MeV and a width of 66±15 MeV is observed in the (Kππ) mass distribution. A spin-parity analysis of the (Kππ) decay Dalitz plot shows the enhancement to be in theJP=1+S(Kϱ) wave and is therefore attributed toQ1-meson production. No evidence is found for the decayQ1→K0ω but limited statistics allow only placing an upper limit of 30% for the decay ratioKω/Kϱ0. TheQ1 production cross section fort(π- →Kππ)>1.2GeV2 is 8±1.3 μb. No evidence is found for the process π-p→Q2Λ withQ2→K*π for which the partial wave analysis gives an upper cross section limit of 2.5 μb at the 95% confidence level.

Exotic exchange processes in K−p and π−p interactions at 4 GeV/c

Abstract Backward production of ω (1670) is observed in the reactions K − p→ φ + φ − ω 0 Λ 0 and K − p→ φ + φ − φ 0 φ 0 for | U Λ | 2 . The cross section for the ω (1670) → φ + φ − ω 0 decay mode is 1.90±0.35 μ b for 8.25 GeV/ c incident K − . Evidence is presented for the importance of the sequential decay, ω (1670) → B φ → ωφφ with a branching ratio ω (1670) → B φ /all ω (1670) → ωφφ =1.0± 0.25 0.00 .

Study of theK s 0 K s 0 system produced in the reactionπ − p→K s 0 K s 0 n at 3.95 GeV/c

Abstract In a high statistics ( ∼150 eV μb ) bubble chamber experiment on K − p interactions at 8.25 GeV c , the study of the reaction K − p → KK Λ provides evidence for an enhancement in the KK system with a mass of (1850 ± 10) MeV and a width of (80 −30 +40 ) MeV. Its possible identification with the missing isosinglet of the 3 − nonet is discussed. A K ∗ K decay mode is also observed.