A measurement of direct photon production in 208 Pb+ 208 Pb collisions at 158 A GeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central collisions is extracted as a function of transverse momentum in the interval 0.5 < pT < 4 GeV/c. A significant direct photon signal, compared to statistical and systematical errors, is seen at pT > 1.5 GeV/c. The results constitute the first observation of direct photons in ultrarelativistic heavy-ion collisions which could be significant for diagnosis of quark gluon plasma formation. 25.75.+r,13.40.-f,24.90.+p 1

In an experiment with a hybrid emulsion spectrometer at Fermilab, the multiplicity and angular characteristics of secondary particles produced in the charged current interactions of nu mu ( nu mu ) with emulsion have been investigated in the framework of a version of the intranuclear cascade model. The data imply that the formation time of the secondary hadrons produced is finite.

Accelerated and decelerated motions of a charged point particle inside medium are studied. It is shown explicitly that in addition to the bremsstrahlung and Cerenkov singular waves, previously unknown electromagnetic singular wave should be observed. It arises when the charge velocity coincides with the light velocity in medium. This wave has the same singularity as theCerenkov one and, therefore, it is more singular than the bremsstrahlung wave. The spacetime regions where these waves exist and conditions under which they appear are determined.

The restoration of chiral symmetry and its subsequent breaking through a phase transition has been predicted to create regions of Disoriented Chiral Condensates (DCC). This phenomenon has been predicted to cause anomalous fluctuations in the relative production of charged and neutral pions in high-energy hadronic and nuclear collisions. The WA98 experiment has been used to measure charged and photon multiplicities in the central region of 158 AGeV Pb+Pb collisions at the CERN SPS. In a sample of 212646 events, no clear DCC signal can be distinguished. Using a simple DCC model, we have set a 90% C.L. upper limit on the maximum DCC production allowed by the data.

Three-particle correlations have been measured for identified pi(-) from central 158A GeV Pb+Pb collisions by the WA98 experiment at CERN. A substantial contribution of the genuine three-body correlation has been found as expected for a mainly chaotic and symmetric source.