The Dalitz plot of η ′ → ηπ + π − decay is studied using (225.2 ± 2.8) × 10 6 J/ψ events collected with the BESIII detector at the BEPCII e + e − collider. With the largest sample of η ′ decays to date, the parameters of the Dalitz plot are determined in a generalized and a linear representation. Also the branching fraction of J/ψ → γη ′ is determined to be (4.84 ± 0.03 ± 0.24) × 10 −3 , where the first error is statistical and the second systematic.

Central + events produced in pp interactions are studied in terms of correlations between the outgoing protons. It is observed there is more 0 (770) and f 2 (1270) production in reactions where the outgoing protons are on opposite sides of the beam. This e ect is not attributable to the trigger or the experimental acceptance, and suggests that the vertices do not factorise.Dedicated to the memory of our colleague and friend Georges Vassiliadis

Alde D. et al. Study of the π o π o-system with the GAMS-4000 spectrometer at 100 GeV/c: IHEP Preprint 98-23.-Protvino, 1998.-p. 24, figs. 11, refs.: 25. The π o π o-system produced in the charge exchange π − p-reaction at 100 GeV/c has been studied. The experiment was performed at the CERN SPS accelerator with the multiphoton hodoscope spectrometer GAMS-4000. A partial wave analysis was carried out in the mass range from 0.8 GeV to 3.0 GeV at −t < 0.2 (GeV/c) 2 with the S, D, G and J waves. The S-wave exhibited rather complicated behaviour with a series of four bumps separated by three dips, at 1 GeV, 1.5 GeV and 2 GeV, which give the evidence for several scalar resonances. Clear peaks corresponding to the f 2 (1270), f 4 (2050) and f 6 (2510) mesons were seen in the higher waves. All the three mesons were produced via a dominating one pion t-channel exchange. The parameters and production cross sections of these mesons were measured. aNNOTACIQ aLDI d. I DR. iZUˆENIE π o π o-SISTEMY NA SPEKTROMETRE gams-4000 PRI IMPULXSE 100 g"w/S: pREPRINT ifw-98-23.-pROTWINO, 1998.-24 S., 11 RIS., BIBLIOGR.: 25. iZUˆENA π o π o-SISTEMA, OBRAZU@]AQSQ W ZARQDOWOOBMENNOJ π − p-REAKCII PRI IMPULX-SE 100 g"w/S.-KSPERIMENT WYPOLNEN NA USKORITELE sps cern. dLQ REGISTRACII γ-KWANTOW OT RASPADOW π o-MEZONOW ISPOLXZOWALSQ GODOSKOPIˆESKIJ MNOGOFOTONNYJ SPEKTRO-METR gams-4000. pARCIALXNO-WOLNOWOJ ANALIZ π o π o-SISTEMY PROWEDEN W INTERWALE MASS OT 0,8 DO 3 g"w S UˆETOM S−, D−, G− I J-WOLN. S−WOLNA IMEET WESXMA SLOVNU@ STRUK-TURU, W NEJ NABL@DAETSQ SERIQ IZˆETYREH BAMPOW, RAZDELENNYH TREMQ PROWALAMI, OKOLO 1, 1,5 I 2 g"w, KOTORYE UKAZYWA@T NA SU]ESTWOWANIE NESKOLXKIH SKALQRNYH REZONANSOW. w WYS[IH WOLNAH NABL@DA@TSQˆETKIE PIKI, SOOTWETSTWU@]IE f 2 (1270)-, f 4 (2050)-I f 6 (2510)-MEZONAM. wSE TRI MEZONA OBRAZU@TSQ PUTEM DOMINIRU@]EGO ODNOPIONNOGO OBMENA. iZME-RENY IH PARAMETRY I SEˆENIQ OBRAZOWANIQ.

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A precise measurement of the vector and axialvector form factors difference F V − F A in the K + → μ + ν μ γ decay is presented. About 95K events of K + → μ + ν μ γ are selected in the OKA experiment. The result is F V − F A = 0.134 ± 0.021(stat) ± 0.027(syst). Both errors are smaller than in the previous F V − F A measurements.