Yu. A. Alexandrov

Measurement of the lifetime

We present the measurement of the lifetime of the Omega_c we have performed using three independent data samples from two different decay modes. Using a Sigma- beam of 340 GeV/c we have obtained clean signals for the Omega_c decaying into Xi- K- pi+ pi+ and Omega- pi+ pi- pi+, avoiding topological cuts normally used in charm analysis. The short but measurable lifetime of the Omega_c is demonstrated by a clear enhancement of the signals at short but finite decay lengths. Using a continuous maximum likelihood method we determined the lifetime to be tau(Omega_c) = 55 +13-11(stat) +18-23(syst) fs. This makes the Omega_c the shortest living weakly decaying particle observed so far. The short value of the lifetime confirms the predicted pattern of the charmed baryon lifetimes and demonstrates that the strong interaction plays a vital role in the lifetimes of charmed hadrons.

Measurement of the polarization of\(\Lambda ^0 , \overline \Lambda ^0 , \Sigma ^ + \) and Ξ− produced in a Σ− beam of 330 GeV/c

AbstractThe polarization of

Neutron optical experiments at the IBR-2 pulsed reactor

\Lambda ^0 , \overline \Lambda ^0 , \Sigma ^ +

What is the mean square charge radius of the neutron actually equal to

andΘ− inclusively produced inσ} induced interactions at 330 GeV has been measured in the experiment WA89 at CERN. This is the first measurement of polarization of baryons produced by an unpolarized hyperon beam. No polarization of

Neutron interferometry at a pulsed source

\overline \Lambda ^0

On the mean square intrinsic charge radius of the neutron

is observed, as was also the case in proton beam data. At transverse momenta of about 1 GeV/c Λℴ and Σ+ show little polarization, significantly lower than in the proton beam data, whileΘ− have a polarization comparable to the polarization of Λ0 produced in proton beams.