Particle theory

Abstract:

We propose a method to identify the parton that gives rise to any particular jet. The method improves with the number of particles in jet, and should indicate which of the jets in a three-jet event at PETRA is the gluon jet. © 1980.

Abstract:

We show that a non-interacting gas of instantons, gives a contribution which vanishes, in QCD, exponentially with N(the number of colours). If we include some of the interactions between instantons, then the resulting dilute gas of instantons-which is now in the form that is used in practice to investigate the structure of hadrons-gives a contribution that is essentialy constant with N. Thus it is entirely consistent for both the N → ∞ limit to be useful and for the dilute gas of instantons to be relevant for the properties of hadrons. © 1980 Springer-Verlag.

Abstract:

We report here the first successful detection of highly relativistic cosmic ray iron group nuclei in the new type of solid state track detector, CR-39 (Allyl diglycol carbonate), in a stack composed of these plastics, nuclear emulsions and other types of plastic detectors, which was exposed in a balloon flight from Hyderabad, India, at 6 mb residual atmosphere for 8 h. The high value of the vertical geomagnetic cut-off rigidity of 16.7 GV ensured the relativistic nature of the particles and these were identified as Fe-group nuclei from the measurements in adjacent sheets of nuclear emulsion. Very well-defined etched cones were observed in the CR-39 plastics after 48 h etch in 6.25 N NaOH at 70 °C, at the locations corresponding to Fe-group nuclei tracks in the nuclear emulsions. The track etch rate (Vt) for relativistic (≥ GeV/nucleon) Fe-group nuclei was measured as 3.5 ± 1.3 μm/h and the bulk etch rate (Vg) as 1.5 ± 0.6 μm/h. The normalised track etch rate, (Vt/Vg) - 1, is compared with the data obtained at lower energies by other workers and the results are found to be consistent. The charge detection threshold for Cr-39 is obtained as Z≈20 for |β {reversed tilde equals} 1. © 1979.