Yu.F. Lomakin

Measurements of the K+→π0e+ν form factors

Abstract The q2 dependence of the vector form factor has been investigated using 3.2 × 104 K+ → π0e+ν decays. The usual linear parametrization. ƒ + (q 2 ) = ƒ(0)(1+λ + q 2 /m π 0 0 ) gives λ+ = 0.0284±0.0027. An analysis of the Dalitz plot density distribution for Ke3+ decays yields the values for the scalar and tensor couplings ƒs and ƒt, and their relative phase angle ost.

Measurement of the Dalitz plot slope parameters for K+→ π+π0π0 decay

We have measured the Dalitz plot slope parameters for the K+ → π+π0π0 decay with an accuracy higher than in previous experiments. The values obtained are substantially different from the world averages. The experiment was performed at the Serpukhov PS with the HYPERON-2 spectrometer at the beam energy 10 GeV We have collected about 33000 events with energies and momenta measured for all involved particles.

On the 1350 MeV Λγ peak produced in π− p interaction

Abstract The existence of the Λγ peak between 1300 and 1400 MeV was supported by our measurements. The explanation of this peak by means of the hypothetical Λη (1680 MeV) resonance can be rejected with a 97% confidence level.

A new upper limit for the branching ratio of the decay K0S → e+e−

Abstract A new value of the upper limit for the branching ratio of the decay of K 0 S into e + e − has been experimentally obtained using a lead glass detector. The value is BR (K 0 S → e + e − ) −4 (90% CL).

Upper limit for the branching ratio of Ks0→e+e− decay

Abstract A search for K s 0 → e + e − decay was performed by means of a 624-channel lead glass shower hodoscope and a set of proportional chambers. Neutral kaons were obtained in the quasibinary charge exchange reaction. A new upper limit of 2.8×10−6 at 90% C.L. for the branching ratio is obtained.

Reconstruction of the coordinate and energy of the electromagnetic shower in the lead-glass hodoscope calorimeter at different entrance angles of 5 GeV positrons

Abstract Energy deposition as a function of entrance angles and coordinates for 5 GeV e + is studied experimentally in 10×10×35 cm 3 blocks of the lead-glass shower hodoscope detector (SHD); the radiation length is X 0 = 2.5 cm. A method for the reconstruction of electromagnetic shower coordinates ( σ ⋍ 11 mm ) and energies ( σ E /E ⋍ 6% ) is developed for the positron entrance angles 0°–30°.

A-dependence of η-meson inclusive production at 10.5 GeV/c

Abstract The experimental results are presented for ratios of ν-meson inclusive differential cross sections in 10.5 GeV/c π+p, π+D and π+A collisions, RD/p=(dσ/dxF)(π+D→ηX)/ (dσ/dxF)π+p→ηX), RA=(dσ/dxF)(π+D→ηX) in the beam fragmentation region. The results are based on the statistics of ≈ 5 × 104 detected η → 2γ decays. It is shown that the power α in the parametrisation RA ≈ Aα(xf) does not change significantly with xF and its mean value is 0.50±0.02. The lower limit is obtained for the effective coefficient with string tension in the colour string model, κ ⩾ 3 GeV/fm. The observed growth of RA with xF can be explained by an assumption of a neutron halo with the factor H ≈ 4 in the nuclei.

Study of the hypercharge exchange reactions π+p→K+∑+ and π+p→K+∑+(1385) at 12 GeV/c

Abstract The results of the study of the π+p→K+∑+ (1) and π+p→K+∑+(1385) (2) reactions at 12 GeV/c are presented. The differential cross sections dσ/dt in|tmin|

Investigation of inclusive production ofK0 andK* (892)0 mesons inK+A interactions at 11.2 GeV

AbstractInclusive production ofK0 andK* (892)0 mesons inK+A-interactions (A=Be, Cu, Pb) at the energy 11.2 GeV has been investigated to study hadronisation of the leading