I. J. G. Scott

Further amplitude analysis of JΨ → γ(π+π−π+π−)

Abstract Mark III data on J Ψ → γ(π + π − π + π − ) have been re-analysed including γσσ final states as well as γϱϱ. Here σ stands for the ππ S-wave amplitude. We fit with I = 0 resonances having JPC = 2++ at 1275 MeV, 0−+ at 1420 MeV, 0++ at 1505 MeV, 2++ at 1640 MeV, 0++ at 1750 MeV and 0++ at 2104 MeV. The 0++ resonances decay dominantly to σσ and the 2++ resonances to ϱϱ.

Further amplitude analysis of J / psi ---> gamma (pi+ pi- pi+ pi-)

Abstract Mark III data on J Ψ → γ(π + π − π + π − ) have been re-analysed including γσσ final states as well as γϱϱ. Here σ stands for the ππ S-wave amplitude. We fit with I = 0 resonances having JPC = 2++ at 1275 MeV, 0−+ at 1420 MeV, 0++ at 1505 MeV, 2++ at 1640 MeV, 0++ at 1750 MeV and 0++ at 2104 MeV. The 0++ resonances decay dominantly to σσ and the 2++ resonances to ϱϱ.

Measurement of the decay distribution of η′ → π+π−γ and evidence for the box anomaly

Abstract The distribution of m ( π + π − ) in the decay η ′ → π + π − γ has been measured with the Crystal Barrel detector. The results are based on a total of 7392 observed η′ decays. The box anomaly constant is extracted from this and its value is found to agree well with theoretical expectations. The pseudoscalar nonet parameters ( f 1 , f 8 and θ PS ) are determined. Finally, we find that there is a problem of consistency between QCD and the standard VDM assumption.

E decays to ηππ in pp annihilation at rest

Abstract We have observed the ηπ + π − and ηπ 0 π 0 decay modes of the E meson in p p annihilation at rest into π + π − π 0 π 0 η . The mass and width of the E meson are 1409 ± 3 and 86 ± 10 MeV. The production and decay branching ratio is B( p p → Eππ)B(E → ηππ) = (3.3 ± 1.0) × 10 −3 . With a spin-parity analysis we determine that J P = 0 − . The observation of the ηπ 0 π 0 decay mode establishes that E is isoscalar ( C = +1). We find that E decays to η ( ππ ) s (where ( ππ ) s is an S-wave dipion) and πa 0 (980)(→ πη ) with a relative branching ratio of (78 ± 16) %. Using the K K π production and decay branching ratio measured earlier we determine that B[E → K K π] B[E → ηππ] = 0.61 ± 0.19 . A comparison with observations in radiative J Ψ decays suggests that E and ι η (1416) are identical.

Observation of f0(1500) decay into KLKL

Abstract The f 0 (1500) is observed in its K K decay mode in an amplitude analysis of high statistics data in p p annihilation at rest into π 0 K L K L . The mass and width is found to be ( m , Γ ) = (1515 ± 20, 105 ± 15) MeV. A comparison of the decay rate into 2 π 0 shows that this state cannot be dominantly s s . The f ′ 2 (1525) has been observed for the first time in p p annihilation and its production rate is consistent with the expectation from the OZI rule.

A study of f0(1500) decays into 4π0 in pp → 5π0 at rest

Abstract Crystal Barrel data on p p → 5π 0 at rest are presented. Mass spectra for 2 π 0 combinations, 3 π 0 and 4 π 0 and decay angular distributions all differ significantly from phase space. We present several ways of fitting the data. All agree on the definite presence of the f 0 (1500), observed in its 4 π 0 decay mode. It can decay into ππ(1300) and into σσ where σ stands for the full ππ S-wave amplitude.

Further analysis of , ηηπ0 and ηπ0π0 at rest

Abstract A fresh analysis is reported of high statistics Crystal Barrel data on p p → 3π 0 , ηηπ 0 , ηπ 0 π 0 and ηη ′ π 0 at rest. This analysis is made fully consistent with CERN-Munich data on π + π − → π + π − up to a mass of 1900 MeV, with GAMS data on π + π − → π 0 π 0 , and with BNL and ANL data on π + π − → K K , which are fitted simultaneously. There is evidence for an I = 0, J PC = 2 ++ resonance with weak (≤ 7%) coupling to ππ, strong coupling to both ϱϱ and ωω and pole position 1534 - i90 MeV. This resonance agrees qualitatively with GAMS and VES data on ππ → ωω, previously interpreted in terms of a resonance at 1590–1640 MeV. New masses and widths for (A) ƒ 0 (1370) and (B) ƒ 0 (1500) , fitted to all eight data sets, are M A = 1300 ± 15 Mev, Γ A = 230 ± 15 MeV, M B = 1500 ± 8 MeV, Γ B = 132 ± 15 MeV. Branching ratios to ππ and ηη are given, and differ significantly from earlier determinations because of a new procedure.

EVIDENCE FOR A JPC = 1++ I = 1 MESON AT 1640 MEV

Abstract From an analysis of p p→4π 0 at a beam momentum of 1940 MeV/c, we find evidence for a J PC =1 ++ resonance at 1640 ±12( stat )±30( syst ) MeV with Γ =300±22±40 MeV; it is observed decaying both to σπ with L =1 and to f 2 (1270) π with L =1.

Decay dynamics of the process η→3π0

Abstract The parameter α =−0.052±0.020 describing the shape of the η →3 π 0 Dalitz plot has been determined using the data from the Crystal Barrel detector at LEAR. The value is compared to predictions of chiral perturbation theory.

Momentum dependence of the decay η→π+π−π0

Abstract The π 0 momentum dependence of the decay η → π + π − π 0 has been measured with the Crystal Barrel detector. The analysis is based on 3230 events. The results of this independent measurement are compared to new chiral perturbation theory calculations and previous measurements.