Particle theory

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.

Abstract:

We show that the contribution of Drell-Yan dynamics to lepton pair production at fixed x, does not scale with energy, but instead decreases as a power of the energy. There is a transition to a different dynamical picture, and the massive photon now probes the quark-antiquark correlation function of the incident hadron, thus providing a unique handle on this quantity. © 1978.

Abstract:

A nonscaling parton model is proposed to describe the large-transverse-momentum processes in hadron collisions. The scale-noninvariance behavior of the parton momentum distribution is deduced from the recent ep and μp deep-inelastic scattering data where gross violation of scaling has been observed. Power-law-breaking effects are parametrized and utilized in the large-pT calculations. The basic subprocess in which the large-angle scattering occurs is taken to be between the partons only. With the normalization as the only adjustable parameter in the theory, we have achieved excellent fits of the pion and proton inclusive cross sections at large pT for various energies. We have also produced a no-parameter fit of the pT dependence of the opposite-side correlation at 90. We predict a dip at y=0 in the rapidity distribution at high pT in the opposite hemisphere, but no data with pT>2 GeV/c are available to check the prediction. The phenomenological success of the nonscaling model therefore on the one hand restores the quark-quark hard-collision subprocess for large-pT reactions, while on the other suggests severe deviation from scaling in lepton-induced interactions at very high Q2. © 1978 The American Physical Society.