Based on a sample of 22 four-prong D 0 / D 0 decays produced in hydrogen by 360 GeV/ c π − , we present the following new results: mean lifetime τ = (3.5 −0.9 +1.4 ) x 10 −13 s ; production cross section for x F > 0.0, σ = (10.3 ± 3.5) ωb ; the D → K ± π ± π + π − branching ratio = (7.1 ± 2.5)%.
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The cross section of the process e+ e- ---> eta gamma has been measured in the 600-1380 MeV c.m. energy range with the CMD-2 detector. The following branching ratios have been determined: B(rho ---> eta gamma) = (3.28 +- 0.37 +- 0.23) 10^{-4}, B(omega ---> eta gamma) = (5.10 +- 0.72 +- 0.34) 10^{-4}, B(phi --> eta gamma) = (1.287 +- 0.013 +- 0.063) 10^{-2}. Evidence for the rho'(1450) ---> eta gamma decay has been obtained for the first time.
The measured Born cross section for the ETA GAMMA final state.
Using the $1.9 pb^{-1}$ of data collected with the CMD-2 detector at VEPP-2M the decay mode $\phi \to \eta \gamma$, $\eta \to \pi^+\pi^-\pi^0$ has been studied. The obtained branching ratio is B($\phi \to \eta \gamma) = (1.18 \pm 0.03 \pm 0.06) %$.
The measured cross section for E+ E- --> PHI < ETA GAMMA>.
The process e+e- to pi+ pi- pi+ pi- pi0 has been studied in the center of mass energy range 1280 -- 1380 MeV using 3.0 1/pb of data collected with the CMD-2 detector in Novosibirsk. Analysis shows that the cross section of the five pion production is dominated by the contributions of the eta pi+pi- and omega pi+pi- intermediate states.
Axis error includes +- 15/15 contribution.
Axis error includes +- 15/15 contribution.
Axis error includes +- 15/15 contribution.
Charm D-meson production in 360 GeV π − p interactions has been studied using the high-resolution hydrogen bubble chamber LEBC and the European Hybrid Spectrometer. The data show evidence for leading quark effects both in the number of D-meson types and in the Feynman x distributions. The production cross section is of the form d 2 δ d x d p T 2 ∞(1-x) n exp (-ap T 2 ) with n = 2.8±0.8 and a = 1.1±0.3 (GeV/ c ) −2 . The x distribution is, however, compatible with the presence of both central ( n = 6) and leading (n = 1) D / D production. The fraction of D-messons in the leading component is estimated to be ≈30%. The rapidity gap between members of reconstructed charm pairs is small compared to the available rapidity range. The inclusive cross section for single D-messons in the forward direction is: δ(D/ D )=(40 8 +15 )μ b ( for x>0) .
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The π − p differential elastic scattering cross sections have been measured for eight momenta in the 33–55 GeV/ c range. The energy dependence of the slope and of the total elastic scattering cross sections has been determined experimentally. The results are compared with the known data. The experimental data are compared both with the Regge pole model and with the quasi-potential one.
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