D.Barberis,W .Beusch,F.G.Binon,A.M .Blick,F.E.Close,K.M .Danielsen, A.V.Dolgopolov,S.V.Donskov,B.C.Earl,D.Evans,B.R.French,T.Hino,S.Inaba, A.V.Inyakin,T.Ishida,A.Jacholkowski,T.Jacobsen,G.T Jones,G.V.Khaustov, T.Kinashi,J.B.Kinson,A.Kirk,W .Klem pt,V.Kolosov,A.A.Kondashov, A.A.Lednev,V.Lenti,S.M aljukov,P.M artinengo,I.M inashvili,T.Nakagawa, K.L.Norm an,J.P.Peigneux,S.A.Polovnikov,V.A.Polyakov,V.Rom anovsky, H.Rotscheidt,V.Rum yantsev,N.Russakovich,V.D.Sam oylenko,A.Sem enov,M .Sen e, R.Sen e,P.M .Shagin,H.Shim izu,A.V.Singovsky,A.Sobol,A.Solovjev, M .Stassinaki,J.P.Stroot,V.P.Sugonyaev,K.Takam atsu,G.Tchlatchidze,T.Tsuru, M .Venables,O.VillalobosBaillie,M .F.Votruba,Y.Yasu.

The reaction pp --> p(f)(pi (0)pi (0)pi (0))p(s) has been studied at 450 GeVc. The pi (0)pi (0)pi (0) effective mass spectrum shows clear eta (547) and pi (2)(1670) signals. Branching ratios for the eta (547) and pi (2)( 1670) are given as well as upper limits for the decays of the omega (782), a(1)(1260) and a(2)(1320) into 3 pi (0). (C) 2001 Published by Elsevier Science B.V.

The reactions pp -> pf (X0) ps, where X0 is observed decaying to pi0pi0pi0pi0, pi+pi-pi0pi0 and pi+pi-pi+pi-, have been studied at 450 GeV/c. There is evidence for an a2(1320)pi decay mode of the eta2(1645) and eta2(1870) in the pi+pi-pi0pi0 and pi+pi-pi+pi- final states. The f2(1950) is consistent with being a single resonance with a dominant f2(1270)pipi decay mode. The f0(1370) is found to decay dominantly to rho-rho while the f0(1500) is found to decay to rho-rho and sigma-sigma.

A search for centrally produced charmonium states has been presented. There is no significant evidence for any charmonium production. An upper limit of 2 nb is found for the cross section of chi(c) production using the decay chi(c)(1P) --> J/psi gamma. (C) 2000 Elsevier Science B.V. All rights reserved.

Ž . The reaction ppTMp vv p has been studied at 450 GeVrc and a spin analysis of the vv channel has been performed f s Ž . PC qq for the first time in central production. Evidence is found for the f 1910 in the J s2 wave with spin projection 2 J s2. This is the only state observed in central production with spin projection J s2. Its dP and f dependencies are Z Z T similar to those observed for other glueball candidates. In addition, evidence is found for a state with J s4 consistent Ž . Ž . with the f 2300 . The f 2000 , previously observed in the rr final state, is confirmed. q 2000 Elsevier Science B.V. All 4 0 rights reserved. Ž . E-mail address: andrew.kirk@cern.ch A. Kirk . 0370-2693r00r$ see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S0370-2693 00 00622-5 ( ) D. Barberis et al.rPhysics Letters B 484 2000 198–204 199 The vv channel has been studied in several different production mechanisms. In pp interactions the vv final state has been studied by the w x w x NA12 1 and VES 2 collaborations. In both experiments clear signals were observed at 1.6 and 1.9 GeV and were found to have J P C s2, called the Ž . Ž . w x f 1640 and X 1910 3 . In addition, the VES 2 collaboration reported evidence for an vv decay Ž . mode of the f 2050 and, more recently, for a 4 P C qq w x J s4 object in the 2.3 GeV region 4 . In pp annihilations C. Baker et al., using the data from the w x Crystal Barrel experiment 5 , have reported eviŽ . dence for a structure similar to the f 1640 in the 2 vv final state but have shown that this state can be Ž . interpreted as being due to the f 1565 previously 2 w x w x observed in the pp final state 3 . The PDG 3 lists Ž . the X 1910 observed in the vv final state with another J P C s2 resonance with similar mass and width observed in the hh final state. In central production the WA102 experiment did not observe Ž . w x the f 1565 in the pp final state 6 , therefore, the 2 centrally produced vv channel can give information Ž . Ž . on the validity of the f 1565 rf 1640 assignment. 2 2 In addition, in the hh final state of the WA102 w x experiment 7 a peak was observed at 1.9 GeV which was consistent in mass and width with the Ž . X 1910 . A spin analysis showed that this state was consistent with having J P C s1 with spin projection J s1 or J P C s2 with spin projection J s Z Z 2. If the latter hypothesis were true then this was the first time that a state had been observed in central production that was produced with spin projection J s2. Hence, if the states observed in vv and hh Z Ž . P C qq are the same and the X 1910 has J s2 , the Ž . X 1910 should be observed in the J s2 projection Z in the vv final state. In central production, the vv final state was previously observed by the WA76 w x experiment 8 but only 80 events were observed and hence no strong conclusions could be drawn. In this paper, a study is presented of the vv final state formed in the reaction ppTMp vv p 1 Ž . Ž . f s at 450 GeVrc. It represents more than a factor of 60 increase in statistics over previous data on the cenw x trally produced vv final state 8 and, moreover, will present a spin analysis of this channel in central production. The data come from the WA102 experiment which has been performed using the CERN Omega Spectrometer, the layout of which is dew x Ž . scribed in Ref. 9 . Reaction 1 has been isolated using the ppp 0 decay mode of both vs. The reaction ppTMp ppppp p 0 p Ž . f s has been isolated from the sample of events having six outgoing charged tracks and four g s reconstructed in the GAMS-4000 calorimeter, by first imposing the following cuts on the components of < < the missing momentum: missing P -17.0 GeVrc, x < < < < missing P -0.16 GeVrc and missing P -0.12 y z GeVrc, where the x axis is along the beam direction. The two photon mass spectrum, when the mass of the other 2g-pair lies within a band around the p 0 Ž . 0 mass 100–170 MeV , shows a clear p signal with small background. Events containing a fast qqŽ . Ž q. D 1232 were removed if M p p -1.3 GeV, f which left 294 463 centrally produced pp ppp p 0 events. Ž q y 0. Fig. 1a shows a lego plot of M p p p versus Ž q y 0. Ž . M p p p four combinations per event . A clear signal of the vv channel can be observed. Fig. 1b shows the ppp 0 mass spectrum if the other ppp 0 combination is compatible with being an Ž Ž q y 0. . v 0.76FM p p p F0.81 GeV where a clear v signal can be observed. A tight cut has been used around the v signal to increase the signal to background ratio in the selected sample. In order to decrease the background further the parameter l is introduced which describes the v decay on the Dalitz plot and is defined as: < < 2 p =p q y ls 2 3 1 2 2 m ymp ž / 4 9 < < where p =p is proportional to the decay matrix q y element for vTMppp , p is the three momen" tum of the p " in the v rest frame and m is the ppp 0 effective mass squared. Superimposed on Fig. 1b as a shaded histogram is the ppp 0 mass distribution for l)0.3. As can be seen the signal to background ratio in the v region has increased. The vv final state has been selected using the ppp 0 mass cuts described above and by requiring that the l)0.3 for each v candidate. The ( ) D. Barberis et al.rPhysics Letters B 484 2000 198–204 200 Ž . Ž q y 0 . Ž q y 0 . Ž . Ž q y 0 . q y 0 Fig. 1. Selection of the vv final state: a M p p p versus M p p p , b M p p p if the other p p p combination is in Ž Ž q y 0 . . Ž . the v band 0.76FM p p p F0.81 GeV . Superimposed as a shaded histogram is the case for l)0.3. c The vv mass spectrum. Superimposed as a shaded histogram is an estimation of the background contribution. resulting vv mass spectrum is shown in Fig. 1c and consists of 5067 events. As can be seen there is a peak in the 1.9 GeV region. The background below the v signal has several sources including combinatorics and other channels. The combinatorial background is removed, in part, in the selection procedure. The remaining background is approximately 27%. Four methods have been used to determine the effects of this background; studying the side bands around the v signal, studying events that do not balance momentum, studying events that do not pass the l selection cuts and studying events from the pppppp channel. Since the majority of the background is due to other physical Ž . Ž . Ž . channels for example a 1260 a 1260 or v a 1260 1 1 1 production, the two methods that best reproduce the background are the one using events that do not pass the l cut and the other uses events from the pppppp channel. These two methods give a very similar representation of the background. ( ) D. Barberis et al.rPhysics Letters B 484 2000 198–204 201 In the remainder of this paper the method used to determine the background will be the mean of these two methods. Superimposed on the vv mass spectrum in Fig. 1c as a shaded histogram is the estimate of the background. A spin analysis of the centrally produced vv system has been performed using the method dew x scribed in Ref. 10 for the rr final state modified for the vv channel. The z axis is defined by the momentum vector of the exchanged particle with the greatest four-momentum transferred in the vv centre of mass. Assuming that only angular momenta up to 4 contribute, the amplitudes have been calculated Ž . in the spin-orbit LS scheme using spherical harmonics. In order to perform a spin parity analysis the log Ž . likelihood function, L sÝ log P i , is defined by j i j combining the probabilities of all events in 50 MeV vv mass bins from 1.5 to 3.0 GeV. The incoherent sum of various event fractions a is calculated so as j to include more than one wave in the fit, Ls log a P i q 1y a 2 Ž . Ž . Ý Ý Ý j j j ž / ž / i j j Ž . where the term 1yÝ a represents the phase space j j background. The negative log likelihood function Ž . w x yL is then minimised using MINUIT 11 . Coherence between different J P states has been neglected in the fit. Different combinations of waves have been tried and insignificant contributions have been removed from the final fit. It is found necessary to introduce the J P C s2 wave with both J s0 and 2, the J P C s0 wave Z and the J P C s4 wave with J s1. The results of Z the best fit are shown in Fig. 2. The J P C s2 wave with J s2 shows a peak Z at 1.9 GeV. This wave has been fitted using a spin 2 relativistic Breit-Wigner and a linear background and is shown superimposed. The fit gives Ms1897"11 MeV, Gs202 " 32 MeV, parameters consistent Ž . X with those of the X 1910 found from a fit to the hh w x final state 7 . Hence this consistent with the fact that Ž . X the X 1910 has vv and hh decay modes, and we Ž . shall refer to it as the f 1910 hereafter. Correcting 2 for the unseen decay modes and the effects of the X Ž . detector, the branching ratio vvrhh of the f 1910 2 is 2.6 " 0.6. There was no evidence for any wave with J s2 in the hh final state of the WA102 Z w x experiment 12 and hence an upper limit for the X Ž . branching ratio hhrhh of the f 1910 has been 2 Ž . calculated to be 0.2 90% CL . The J P C s2 wave with J s0 shows a broad Z enhancement. Superimposed on the wave is a shaded Ž . histogram representing the f 1640 . As can be seen 2 the J P C s2 wave with J s0 is not compatible Z Ž . with the f 1640 observed by other experiments. 2 This non observation does not contradict the claim Ž . that the f 1640 is an vv decay mode of the 2 Ž . f 1565 since this state is also not observed in 2 central production. The J P C s0 wave shows some activity near threshold and a broad enhancement around 2 GeV. In a previous analysis of the 4p channel, the WA102 experiment observed a similar structure in the J P C s0 rr wave which was identified with the Ž . f 2000 . Superimposed on the wave is a shaded 0 Ž . histogram representing the f 2000 assuming that 0 the branching ratio rrrvv s 3 as expected for a isoscalar resonance. This well represents the wave in the 2 GeV region. The J P C s4 wave with

A partial wave analysis of the centrally produced eta pi(0) and eta pi(-) channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. Clear a(0)(980) and a(2)(1320) signals have been observed in S and D+ waves respectively. The dP(T), phi and \t\ distributions of these resonances are presented. (C) 2000 Elsevier Science B.V. All rights reserved.

The production and decay properties of the f(0)(1370), f(0)(1500), f(0)(2000) and f(2)(1950) have been studied in central pp interactions at 450 GeV/c. The dP(T), phi and \t\ distributions of these resonances are presented. For the J= 0 states, the f(0)(1370) and f(0)(2000) have similar dP(T) and phi dependences. These are different to the dP(T) and phi dependences of the f(0)(980), f(0)(1500) and f(0)(1710). For the J = 2 states the f(2)(1950) has different dependences to the f(2)(1270) and f(2)(1520). This shows that the dP(T) and phi dependences are not just J phenomena. (C) 2000 Published by Elsevier Science B,V. All rights reserved.

A search for centrally produced charmonium states has been presented. There is no significant evidence for any charmonium production. An upper limit of 2 nb is found for the cross section of x production using the decay c

Evidence is presented that the Pomeron acts as a non-conserved vector current. A study has been made of the azimuthal angle phi, 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 moder 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 pi-Pomeron exchange, the phi distribution is flat. (C) 1999 Elsevier Science B.V. All rights reserved.

Small Angle Detector (SAD-150) is a PbWO4 heavy crystal electromagnetic calorimeter with high energy and coordinate resolution for multiphoton events. It has been included in the GAMS-4π setup and calibrated in muon and electron beams. Test measurements of forward emitted π0 and η in the π− p charge exchange reactions with 32.5 GeV/c π− at the IHEP proton synchrotron are reported. The measured mass resolution in the η region agrees with the design value. SAD-150 performance does not deteriorate with π− intensities up to 106 π−/s per cell.

A coupled channel analysis of the centrally produced K q K y and p q p y final states has been performed in pp collisions . at an incident beam momentum of 450 GeVrc. The pole positions and branching ratios to pp and KK of the f 980 , 0

A coupled channel analysis of the centrally produced K + K and + nal states has been performed in pp collisions at an incident beam momentum of 450 GeV/c. The pole positions and branching ratios to and KK of the f0(980), f0(1370), f0(1500) and f0(1710) have been determined. A systematic study of the production properties of all the resonances observed in the + and K + K channels has been performed.

A partial wave analysis of the centrally produced K+K− and KS0KS0 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 f′2(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 π0π0 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.

qy

A study has been made of pseudoscalar mesons produced centrally in pp interactions. The results show that the eta and etaprime appear to have a similar production mechanism which differs from that of the pi0. The production properties of the eta and etaprime are not consistent with what is expected from double Pomeron exchange. In addition the production mechanism for the eta and etaprime is such that the production cross section are greatest when the azimuthal angle between the pT vectors of the two protons is 90 degrees.

Ž q y q y. Ž q y q y 0. A study of the reactions ppTMp p K K p p and ppTMp p K K p p p shows evidence for the f s f s ) ) ) ) Ž . Ž . Ž . Ž . K 892 K 892 and fv channels respectively. The K 892 K 892 mass spectrum shows a broad distribution with a maximum near threshold and an angular analysis shows that it is compatible with having J s2. The behaviour of the cross-section as a function of centre of mass energy, and the four momentum transfer dependence, are compatible with what ) ) Ž . Ž . would be expected if the K 892 K 892 system was produced via double Pomeron exchange. The dP behaviour of the T fv channel is similar to what has been observed for all the undisputed qq states. In contrast, the dP behaviour of the T ) ) Ž . Ž . K 892 K 892 final state is similar to what has been observed for the ff final state and for previously observed glueball candidates. q 1998 Elsevier Science B.V. All rights reserved. Experiment WA102 is designed to study exclusive final states formed in the reaction ppTMp X 0 p 1 Ž . Ž . f s at 450 GeVrc. The subscripts f and s indicate the fastest and slowest particles in the laboratory respectively and X 0 represents the central system that is presumed to be produced by double exchange processes. The experiment has been performed using the CERN Omega Spectrometer, the layout of which is w x described in Ref. 1 . In previous analyses of other channels it has been observed that when the centrally produced system has been analysed as a function of the parameter dP , which is the difference in the T transverse momentum vectors of the two exchange w x particles 1,2 , all the undisputed qq states are suppressed at small dP , in contrast to glueball candiT dates. In addition, it has recently been suggested w x 3,4 that this suppression could be due to the fact that the production mechanism is through the fusion of two vector particles. It is therefore interesting to make a study of the dP dependence of systems T decaying to two vectors. In a recent publication we have performed a study of the centrally produced w x ff final state 5 , which was found to act like the glueball candidates that have been observed. ) Ž . This paper presents a study of the K 892 ) Ž . K 892 final state formed in the reaction ppTMp KKpp p 2 Ž . Ž . f s and the fv final state formed in the reaction ppTMp KKppp 0 p 3 Ž . Ž . f s and represents a factor ten increase in statistics over w x previously published data samples 6 . Ž . Events corresponding to reaction 2 have been isolated from the sample of events having six outgoing charged tracks by first imposing the following cuts on the components of the missing momentum: < < < < missing P -14.0 GeVrc, missing P -0.12 x y < < GeVrc and missing P -0.08 GeVrc, where the x z axis is along the beam direction. A correlation between pulse-height and momentum obtained from a system of scintillation counters was used to ensure that the slow particle was a proton. In order to select the KKpp system, inforˇ mation from the Cerenkov counter was used. An event was accepted if a positive or negative particle was identified as a Krp and the other particle with the same charge was consistent with being a p . A w x modified method of Ehrlich et al. 7 , has been used to compute the mass squared of the two highest momentum central particles assuming the other two particles to be pions. The resulting distribution is . shown in Fig. 1a where a clear peak can be seen at the kaon mass squared. This distribution has been fitted with Gaussians to represent the contributions from the pppp channel and the KKpp channel. From this fit the number of KKpp events is found to be 13950 " 420. A cut on the Ehrlich mass squared of 0.16FM 2 F0.54 GeV 2 has been used to select a sample of KKpp events. The mass of the Kp pair is plotted against the mass of the Kp pair in Fig. ) ) . Ž . Ž . 1b and shows a strong K 892 K 892 signal. The two possible Kp mass combinations are . ) Ž . plotted in Fig. 1c . A clear K 892 signal can be seen together with an enhancement at 1.4 GeV. A fit has been performed to this spectrum using two ( ) D. Barberis et al.rPhysics Letters B 436 1998 204–210 206 q y q y . . Ž y q. Ž q y. . Fig. 1. For the K K p p channel a the Ehrlich mass squared distribution, b the lego plot of m K p versus m K p , c the " . . " . . " ) Ž . K p mass spectrum and d the K p mass spectrum after selecting the K p mass to lie in the K 892 band. ) Ž . Breit-Wigners to describe the K 892 and the peak Ž at 1.4 GeV, and a background of the form my .a Ž 2 . m exp ybmycm where m is the Kp mass, th m is the threshold mass and a, b and c are fit th parameters. The result of the fit gives m s896 " 2 1 MeV and G s54 " 3 MeV, compatible with the 1 w x ) Ž . PDG values 8 for the K 892 and m s1436 " 8 2 MeV and G s196 " 45 MeV, compatible with the 2 ) Ž . PDG values for either the K 1430 or the the 0 ) Ž . K 1430 . By selecting one Kp mass to lie within a 2 ) Ž . Ž band around the K 892 mass from 0.73 1.06 . GeV and plotting the effective mass of the other . pair, the spectrum of Fig. 1d was produced. A ) Ž . strong K 892 signal is observed confirming the ) ) Ž . Ž . presence of the K 892 K 892 final state. There ) Ž . ) Ž . is no evidence for K 892 K 1430 production. The number of events in nine regions around the ) ) Ž . Ž . K 892 K 892 position in the Kp scatter plot is . shown in Fig. 2a . From these numbers and applying ) Ž . a correction for the tails of the K 892 the total ) ) Ž . Ž . number of K 892 K 892 events is found to be 2027 " 113 events. In order to compare the produc) ) ) Ž . Ž . Ž . tion rates for K 892 Kp and K 892 K 892 , ) Ž . the number of K 892 Kp events has been estimated. This was done by subtracting twice the num) ) Ž . Ž . ber of K 892 K 892 events from the total num) Ž . . ber of K 892 s observed in Fig. 1c , and this gives ) Ž . 6281 " 340 K 892 Kp events. The geometrical acceptance has been found to be ) ) ) Ž . Ž . Ž . similar for K 892 K 892 and K 892 Kp production. After correcting for unseen decay modes of ) Ž . the K 892 , the ratio of cross sections is estimated ( ) D. Barberis et al.rPhysics Letters B 436 1998 204–210 207 q y q y . Fig. 2. For the K K p p channel a a scatter table of y q q y ) ) Ž . Ž . Ž . Ž . m K p against m K p in the K 892 K 892 region ) ) . Ž . Ž . and b the background subtracted K 892 K 892 mass spectrum. ) " . ) ) Ž Ž . . Ž Ž . Ž .. to be s K 892 K p rs K 892 K 892 s2.06 " 0.13. We can also calculate the number of q y q y ) Ž . K K p p events that do not include a K 892 . using the fit to Fig. 1a which gives 5642 " 550 q y q y ) Ž . K K p p events. Although the K 892 ) Ž . K 892 final state is a major component of the KKpp channel it is not the dominant component. In contrast, the ff final state was found to be the dominant component of the KKKK chanw x nel 5 . After correcting for geometrical acceptances, detector efficiencies, losses due to cuts, charged kaon decay and unseen decay modes, the cross-section for ) ) ' Ž . Ž . K 892 K 892 production at s s29.1 GeV in ) ) < < Ž Ž . Ž .. the x interval x F0.2 is s K 892 K 892 F F s85 " 10 nb. This can be compared with the ' cross-sections found in the same interval at s s12.7 w x and 23.8 GeV 6 of 67" 16 nb and 70 " 14 nb respectively. This effectively constant cross-section as a function of energy is consistent with the ) ) Ž . Ž . K 892 K 892 system being produced by a DouŽ . ble Pomeron Exchange DPE mechanism which is w x similar to what was found for the ff final state 5 . In the KKpp channel we have also searched for associated fr production but have found no evidence for this channel and can place an Ž . upper limit on the cross section of s fr 0.7 nb Ž . 95 % confidence limit . ) ) Ž . Ž . In order to obtain a K 892 K 892 mass spectrum free from background we have used the nine bin method described above to calculate the number ) ) Ž . Ž . of K 892 K 892 events in 50 MeV mass inter) ) Ž . Ž . vals. The resulting K 892 K 892 effective mass . spectrum is shown in Fig. 2b and as can be seen shows a broad distribution with a maximum near threshold. ) Ž . The angular distributions of the K 892 ) Ž . K 892 system can be used to determine the spin) ) Ž . Ž . parity of the intermediate K 892 K 892 state usw x ing a method formulated by Chang and Nelson 9 w x and Trueman 10 . Three angles have to be considered: the azimuthal angle x , between the two ) Ž . K 892 decay planes and the two polar angles u1 ) Ž . and u of the K s in their respective K 892 rest 2 ) Ž . frames relative to the K 892 momenta in the ) ) Ž . Ž . K 892 K 892 rest frame. Table 1 The b , z and chi-squared values for different spins of the ) ) Ž . Ž . K 892 K 892 system P J L S b z chi-squared q 0 0 0 2r3 0 54 q 0 2 2 1r3 1 175 y 0 1 1 y1 y1 314 y 1 1 1 0 1r2 68 q 1 2 2 0 1r2 68 q 2 0 2 1r15 0 18 q 2 2 0 2r3 0 54 q 2 2 2 2r21 3r14 30 y 2 1 1 y2r5 y1r10 64 y 2 3 1 y31r5 y2r3 139 ( ) D. Barberis et al.rPhysics Letters B 436 1998 204–210 208 ) ) Ž . Ž . For a K 892 K 892 sample of unique spinparity and free of background the distribution of x Ž . takes the form dNrdxs1qbcos 2 x where b is a constant which depends only on the spin-parity of ) ) Ž . Ž . the K 892 K 892 system and is independent of Ž . its polarisation. Similarly dNrdcosus1q zr2 Ž 2 . 3cos uy1 . Values of b and z for different spinw x parity states are given in Table 1 11 . The x and cosu distributions have been obtained by calculating ) ) Ž . Ž . the number of K 892 K 892 events from the nine bins in 9 intervals of x and 10 intervals of cosu . The resulting distributions are shown in Fig. . . 3a and b for x and cosu respectively. A chi-squared fit has been performed to these spectra using the distributions expected for a single state with a given value of J . The results of the fit are given in Table 1 and as can be seen the lowest chi-squared is for a P q Ž . fit using J s2 Ls0, Ss2 with bs1r15 and zs0. As can be seen the J P s0 and 0 hypotheses can be clearly ruled out. A fre

The π0π0-system produced in the π−p-reaction at 100 GeV/c has been studied at the CERN SPS accelerator with the spectrometer GAMS-4000. A partial wave analysis has been performed in the mass range from 0.8 GeV to 3 GeV at −t<0.2 (GeV/c)2 with the S, D, G and J waves. The S wave exhibits a complicated structure with a series of bumps separated by three dips, at 1 GeV, 1.5 GeV and 2 GeV. Clear peaks corresponding to the f2(1270), f4(2050) and f6(2510) mesons are seen in the higher waves. The mesons are produced via dominating one pion exchange in the t-channel. Parameters and production cross sections of the mesons are measured.

The reaction $\pi^-p \to \eta\pi^o n$ has been studied with GAMS-2000 spectrometer in the secondary 38 GeV/c $\pi^-$-beam of the IHEP U-70 accelerator. Partial wave analysis of the reaction has been performed in the $\eta\pi^o$ mass range up to 1200 MeV. The $a_0(980)$-meson is seen as a sharp peak in S-wave. The $t$-dependence of $a_0(980)$ production cross section has been studied. Dominant production of the $a_0(980)$ at a small transfer momentum $t$ confirms the hypothesis of Achasov and Shestakov about significant contribution of the $\rho_2$ exchange ($I^GJ^{PC}=1^+2^{--}$) in the mechanism of $a_0(980)$ meson production in $t$-channel of the reaction.