A.V. Kulikov

Observations of atoms consisting of π+ and π− mesons

Abstract In the experiment 272±49 atoms consisting of π + and π + − mesons were observed. The atoms were produced in a Ta target by 70 GeV protons and π + and π − mesons were detected from the atom break-up in the same target.

Experimental estimation of the lifetime of atoms formed by π+ and π− mesons

Abstract Based on observation [L.G. Afanasyev et al., Phys. Lett. B 308 (1993) 200] of 272±49 atoms formed by π + and π − an estimation of the atom lifetime in the ground (1S) state is obtained: τ 1 = (2.9 +∞ −2.1 ) · 10 −15 s or τ 1 > 0.6·10 −15 s at 90% confidence level. Atoms were produced in inclusive p Ta interactions at 70 GeV.

Measurement of the branching ratio for the π0-meson decay into a photon and a positronium atom

Abstract The ratio of the number of ultrarelativistic positronium atoms ( A 2e ) to the photon number in the momentum interval 800–2000 MeV/ c has been measured in pC interactions at E p =70 GeV and at an angle of 8.4° in the laboratory frame. The branching ratio ϱ π =(1.84±0.29)×10 -9 for π 0 decay into a photon and A 2e has been obtained. The parameter ϱ π is determined by the conversion probability ϱ A of a time-like photon into A 2e in radiative decays of elementary particles.

Observation of the Coulomb interaction effect in pion pairs from the reaction p + Ta → π+ + π− + X at 70 GeV

Abstract Pion pair production from the proton-tantalum nuclear interaction at proton energy 70 GeV has been studied. Pion correlations as a function of the relative momentum in a pair CMS have been measured at the relative momentum region below 40 MeV/ c . The experimental data agree with the calculation that takes into account the Coulomb factor in the differential cross section of pion pairs production.