V.A. Polyakov

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}

The parameters of the Dalitz diagram for the decay η′ → ηπ0π0 in a generalized and a linear representation were determined by using a statistical sample of 15 × 103 events. A charge-exchange reaction at a momentum of 32 GeV/c was a source of monoenergetic η′ mesons. The experiment was performed with the aid of the GAMS-4π spectrometer.

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

Heavy neutrino nu_h with m_h mu nu_h (nu_h -> nu gamma) decay chain in the following parameter region: 30MeV/c^2 < m_h < 80MeV/c^2; 10^{-11}sec < tau_h < 10^{-9}sec. For the whole region |U_{mu h}|^2 < 5 x 10^{-5} for Majorana type of nu_h and | U_{\mu h}|^2 < 8 x 10^{-5} for the Dirac case.

f_{1}

Heavy neutrino nu_h with m_h mu nu_h (nu_h -> nu gamma) decay chain in the following parameter region: 30MeV/c^2 < m_h < 80MeV/c^2; 10^{-11}sec < tau_h < 10^{-9}sec. For the whole region |U_{mu h}|^2 < 5 x 10^{-5} for Majorana type of nu_h and | U_{\mu h}|^2 < 8 x 10^{-5} for the Dirac case.

(1710)

The decay K− → μ−νπ0 has been studied using in-flight decays detected with the ISTRA+ setup operating in the 25-GeV negative secondary beam of the U-70 PS. About 112K events were used for the analysis. The λ+ and λ0 slope parameters of the decay form factors f+(t) and f0(t) have been measured: λ+=0.0321±0.004(stat.)±0.002(syst.), λ0=0.0209±0.004(stat.)±0.002(syst.); the correlation dλ0/dλ+=−0.46. The limits on the possible tensor and scalar couplings have been derived: fT/f+(0)=−0.021±0.028(stat.)±0.014(theor.), fS/f+(0)=0.004±0.005(stat.)±0.005(theor.).

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

The decay K− → e−νπ0 has been studied using in-flight decays detected with the ISTRA+ setup working at the 25-GeV negative secondary beam of the U-70 PS. About 130K events were used for the analysis. The λ+ parameter of the vector form factor has been measured: λ+=0.0293±0.0015(stat.)±0.002(syst.). The limits on the possible tensor and scalar couplings have been derived: fT/f+(0)=−0.045±0.060(stat.) and fS/f+(0)=−0.019−0.016+0.025(stat.).

Study offo (995) resonance in the π0π0 decay channel

X iv :1 30 1. 69 87 v2 [ he pex ] 4 F eb 2 01 3 Measurement of the η − η mixing angle in π and K beams with GAMS-4π Setup S.V. Donskov, V.N. Kolosov, A.A. Lednev, Yu.V. Mikhailov, V.A. Polyakov, V.D. Samoylenko, ∗ and G.V. Khaustov Institute for High Energy Physics, Protvino, Russia The results of mixing angle measurement for η′, η mesons generated in charge exchange reactions with π− and K− beams are preseneted. When the η′, η mesons are described in nonstrange(NS)– strange(S) quark basis the π− and K− beams allow to study |ηq〉 and |ηs〉 parts of the meson wave function. The cross section ratio at t′ = 0 (GeV/c) in the π− beam is Rπ(η ′/η) = 0.56± 0.04 and result in mixing angle φP = (36.8± 1.) . For K− beam the ratio is RK(η ′/η) = 1.30± 0.16. It was found that gluonium content in η′ is sin ψG = 0.15 ± 0.06. The experiment was carried out with GAMS-4π Setup.

Measurement of the matrix element for the decay η′ → ηπ0π0 with the GAMS-4π spectrometer

Using data collected with the ISTRA+ spectrometer during the 2001 run of the U-70 proton synchrotron in Protvino, the first observation of the radiative kaon decay K− → µ−π0γν is reported. The ratio Br(Kµ3γ, 5 < E*γ < 30 MeV)/Br(Kµ3) is found to be [0.270 ± 0.029(stat.) ± 0.026(syst.)]% and the ratio Br(Kµ3γ, 30 < E*γ < 60 MeV)/Br(Kµ3) = [0.0448 ± 0.0068(stat.) ± 0.0099(syst.)]%. These ratios are consistent with the theoretical predictions 0.21 and 0.047%, respectively. The measured angular distribution asymmetry for the region 5 < E*γ < 30 MeV, A(cos ϑ*µγ) = 0.093 ± 0.141, is two standard deviations away from the theoretical prediction of 0.354. The measured asymmetry in the T-odd variable ξ = pγ · (pµ × pπ)/mK3 is −0.03 ± 0.13.Using data collected with the ISTRA+ spectrometer during the 2001 run of the U-70 proton synchrotron in Protvino, we report the first observation of the radiative kaon decay K- -->mu-pi0gammanu. We find Br(Kmu3g)/Br(Kmu3) for two regions 5<Eg<30 and 30<Eg<60 MeV consistent with theoretical predictions. The measured angular distribution asymmetry for the first region, 0.093+/-0.141, is two standard deviations away from the theoretical prediction of 0.354. The measured asymmetry in the T-odd variable is -0.03+/-0.13.