V. Lenti

A study of the ηπ+π− channel produced in central pp interactions at 450 GeV/c

The reaction pp ->pf (eta eta) ps has been studied at 450 GeV/c. For the first time a partial wave analysis of the centrally produced eta eta system has been performed. Signals for the f0(1500), f0(1710) and f2(2150) are observed and the decay branching fractions of these states are determined.

Observation of a narrow scalar meson at 1450 MeV in the reaction pp → pƒ(π+π−π+π−)ps at 450 GeV/c using the CERN Omega spectrometer

Abstract The reaction pp → pƒ(π + π − π + π − )p s has been studied at 450 GeV/c in an experiment designed to search for gluonic states. In addition to the well known ƒ 1 (1285) , the π+π−π+π− mass spectrum shows evidence for two states pre only observed by the WA76 experiment, the X(1450) and X(1900). An analysis of the X(1450) shows that it is a relatively narrow state (Γ = 56 ± 12 MeV) with I(JPC) = 0(0++) which decays to ϱ0π+π−. The X (1900) could either b single broad state (Γ = 370±70 MeV) with I(JPC) = 0(2++) or possibly separate states.

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.

A partial wave analysis of the centrally produced

A partial wave analysis of the centrally produced K+K- and K0K0 channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found in each channel. The striking feature is the observation of peaks in the S-wave corresponding to the f0(1500) and fJ(1710) with J = 0. The D-wave shows evidence for the f2(1270)/a2(1320), the f2(1525) and the f2(2150) but there is no evidence for a statistically significant contribution in the D-wave in the 1.7 GeV mass region.A partial wave analysis of the centrally produced K+K- and K0K0 channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found in each channel. The striking feature is the observation of peaks in the S-wave corresponding to the f0(1500) and fJ(1710) with J = 0. The D-wave shows evidence for the f2(1270)/a2(1320), the f2(1525) and the f2(2150) but there is no evidence for a statistically significant contribution in the D-wave in the 1.7 GeV mass region.

K^{+}K^{-}

Abstract A study of the f 1 (1285) and f 1 (1420) produced in central pp interactions has been performed. For the first time in a single experiment the branching fractions of both mesons in all major decay modes have been determined. Both the f 1 (1285) and f 1 (1420) are consistent with being produced by double Pomeron exchange.A study of the f1(1285) and f1(1420) produced in central pp interactions has been performed. For the first time in a single experiment the branching fractions of both mesons in all major decay modes have been determined. Both the f1(1285) and f1(1420) are consistent with being produced by double Pomeron exchange.

and

Abstract Results from the WA85 Experiment at the CERN Ω Spectrometer are presented. A 200 A GeV/ c beam of 32 S ions was used with a tungsten target. The apparatus is used to detect V 0, s and charged tracks in the range p T > 0.9 GeV/ c and 2.3 Y lab Λ and negative hadrons all show a linear increase with rapidity density in the range 70–140 as expected from models based on a superposition of independent NN collisions.

K^{0}_{s}K^{0}_{s}

Abstract An analysis of the centrally produced π + π − and π + π − π + π − mass spectra from the WA76 and WA91 experiments is presented, which shows that in the π + π − π + π − channel there are two new states, the f 0 (1450) and f 2 (1900). There is another new state in the π + π − channel with M = 1497 ± 30 MeV and Γ = 199 ± 30 MeV, which is compatible with the f 0 (1520) observed by the Crystal Barrel experiment. Another interpretation is discussed, where the 1450 and 1497 GeV structures are explained as being due to an interference effect between the f 0 (1365) and f 0 (1520).

systems in pp interactions at 450 GeV/c and new information on the spin of the

The reaction pp ->pf (pi+pi-pi+pi-) ps has been studied at 450 GeV/c in an experiment designed to search for gluonic states. A spin analysis has been performed and the dPT filter applied. In addition to the well known f1(1285) there is evidence for two JPC=2-+ states called the eta2(1620) and eta2(1875) and a broad scalar called the f0(2000). The production of these states as a function of the dPT kinematical filter shows the behaviour expected for qqbar states. In contrast, there is evidence for two states at 1.45 GeV and at 1.9 GeV which do not show the behaviour observed for qqbar states.Abstract The reaction pp → pf(π+ π− π+ π−)ps has been studied at 450 GeV/c in an experiment designed to search for gl states. A spin analysis has been performed and the dPT filter applied. In addition to the well know f1(1285) there is evidence for two JPC = 2−+ states called the η2(1620) and η2(1875) and a broad scalar called the f0(2000). The production of these states as a function of the dPT kinematical filter shows the behaviour expected for q q states. In contrast, there is evidence for two states at 1.45 GeV and at 1.9 GeV which do not show the behaviour observed for q q states.

f_{1}

Abstract The K + K − and K S 0 K S 0 systems centrally produced in the reaction pp→p f K K p s have been studied at 300 GeV/ c incident momentum. Both the K + K − and the K S 0 K S 0 mass spectra show large resonant production. For the first time in hadron collisions, clear evidence is found for the θ f 2 (1720) with parameters m =1713±10 MeV, Γ =181±30 MeV for the K + K − decay mode and m =1706±10 MeV, Γ =104±30 MeV for the K S 0 K S 0 decay mode. A spin analysis of the K + K − spectrum shows that for the θ f 2 (1720) J P =2 + is strongly favoured while 0 + and 1 − are excluded.

(1710)

Abstract Evidence is presented that the Pomeron acts as a non-conserved vector current. A study has been made of the azimuthal angle φ , which is defined as the angle between the p T vectors of the two outgoing protons, in the reaction pp → pp ( X 0 ) for those resonances ( X 0 ) which are compatible with being produced by double Pomeron exchange. These distributions have been compared with a model which describes the Pomeron as a non-conserved vector current and a qualitative agreement is found. In addition, when one of the particles exchanged is known to have spin 0, namely π –Pomeron exchange, the φ distribution is flat.