S. A. Polovnikov

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^{-}

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.

and

A high-statistics study of the π0π0-system produced in the π-p→π0π0n reaction at 38GeV/c has been carried out at the IHEP accelerator using the GAMS-2000 multiphoton spectrometer. A partial-wave analysis which includesS, D0, D− andD+ waves has been performed in the |t|-range up to 1 (GeV/c)2. TheS*/f0(980) resonance is seen as a dip in theS-wave amplitude at small |t|. A distinct peak with a mass of 997±5MeV and a width of 48±10MeV is observed in theS-wave at |t|>0.3 (GeV/c)2. The production cross sections are measured.

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

Abstract Central π+π− events produced in pp interactions are studied in terms of correlations between the outgoing protons. It is observed there is more ϱ0(770) and f2(1270) production in reactions where the outgoing protons are on opposite sides of the beam. This effect is not attributable to the trigger or the experimental acceptance, and suggests that the vertices do not factorise.

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

Abstract New data on the ν′ν system produced in the π−p charge exchange at 38 GeV c momentum confirm the existence of the narrow ν′ν resonance X(1910). The hypothesis of the X(1910) quantum numbers being a JPC = 1−+, forbidden for the q[ovbar|q] meson, is proposed to explain the extremely low limits obtained for X(1910) decays through π0π0, νν and K0sK0s channels and the flat t-dependence of the X(1910) production cross section.

f_{1}

The reaction pp ! pf( 000 )ps has been studied at 450 GeV/c. The 000 eective mass spectrum shows clear (547) and 2(1670) signals. Branching ratios for the (547) and 2(1670) are given as well as upper limits for the decays of the !(782), a1(1260) and a2(1320) into 3 0 .The reaction pp ->pf (pi+pi-pi0) 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. The analysis confirms the previous observation that all undisputed qqbar states are suppressed at small dPT. In addition, a clear difference is observed in the production mechanism for the eta and omega.

(1710)

Abstract The lead tungstate (PWO) heavy crystal calorimeter is tested in a GAMS-type experiment detecting 50 000 π 0 -mesons produced in a 32.5 GeV/ c intensive π − beam of the 70 GeV IHEP accelerator. In spite of a huge beam load of the calorimeter cells (up to 10 6 π − /s), a clean π 0 → 2 γ signal is observed. The measured PWO spectrometer mass resolution is in good accordance with previous electron beam tests and GEANT calculations. A high precision of the real-time PWO spectrometer calibration, using the π 0 signal during the physics run, is achieved. The results of these very first spectrometric beam tests demonstrate a high performance of multicell PWO spectrometers in heavy-load high energy physics experiments of both fixed target and collider types.

A study of the centrally produced π+π-π+π- channel in pp interactions at 450 GeV/c

Abstract A partial wave analysis of the centrally produced π 0 π 0 channel has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found. Evidence is found for the f 0 (980), f 0 (1300) and f 0 (1500) in the the S -wave. and the f 2 (1270) is observed dominantly in the D 0 − -wave. In addition, there is evidence for a broad enhancement in the D -wave below 1 GeV.A partial wave analysis of the centrally produced pi0pi0 channel has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found. Evidence is found for the f0(980), f0(1300) and f0(1500) in the the S-wave. and the f2(1270) is observed dominantly in the D0-wave. In addition, there is evidence for a broad enhancement in the D-wave below 1 GeV.

Study offo (995) resonance in the π0π0 decay channel

The rare ηγ decay width of the ω-meson has been measured in a model-independent way, with ω produced in 38 GeV/c π−p charge-exchange. Large momentum transfer events have been selected in order to eliminate ω-ρ interference contribution. BR (ω→ηγ) =(8.3±2.1)·10−4. The gammas from ω→ηγ→3γ decay have been detected with the multiphoton spectrometer GAMS-2000 at the IHEP 70 GeV proton accelerator.

Observation of vertex factorisation breaking in central pp interactions

SummaryRecent results on ωπ0 partial-wave analysis from the GAMS Collaboration are presented. A partial-wave analysis of the 38 GeV/c π-p charge exchange data confirmed the existence of theρ(2200) radial-orbital excitation of theρ(770) ground-state observed earlier in the same experiment. A new 5−− state,π5(2350), was also observed in this analysis. Masses, widths and production cross-sections for these states are given.