Experimental Study ofp+p→p+N*at Incident Energies of 6-30 BeV

Abstract

associated with phase diffusion brought about by a random noise perturbation due to thermal fluctuations. In the quantum theory, the process of contraction of the density matrix after the decay of each injected atom would convert even a pure case into a mixture, so that Eqs. (2) really describe an ensemble of lasers for which phase information is gradually lost. The density matrix does not describe the laser but rather our state of knowledge of the ensemble of lasers under consideration. If we knew initially that a single laser had a nonvanishing electric field, a density matrix with nonzero off-diagonal elements would be required for the initial description, and the average electric field would only decay with the very long mean life of 1/D.

Nucleon Isobar Production in Proton-Proton Collisions between 3 and 7GeVc

“…3,6,7 Unlike the situation at low momentum transfers, the information on reaction (1) at medium and hlgh momentum transfers [-t ~ 0.5 (GeV /c)2] has been confined to a few isolated data points. 2,5, 6…”

Isobar Production inp+p→p+p+π++π−AT 6

“…The present experiment would therefore predict a 0.44± 0.1 mb enhancement for the mass band near 1.45 GeV if only the recoil proton is observed. This prediction may be compared with the result of Anderson et al 4 who quote a 0.544 ± 0.090 mb cross section at 10 GeV/c for their enhancement. A rough extrapolation of their result to 6.6 GeV/c leads to ~0.4± 0.1 mb.…”

“…4 is due to the P lx resonance and that the inelasticity of this channel 8 is due to the N2ir decay, either through iV*77 or through N(2u) with the di-pion in the T = 0 channel, 9 then the results of Anderson et al 4 may be used to estimate the enhancement which we should see in the N* ++ ir~ channel. This estimate leads to (0.4± 0.1)x (0.34± 0.04)x (f or f)-0.09 ± 0.03 mb, which does not appear consistent with our result of 0.22± 0.05 mb.…”

“…Furthermore, the enhancement which we do observe can account quantitatively for the low-mass enhancement observed in counter experiments at nearby momenta. 4 ' 5 The dominance of peripheral Af* ++ (1238) production in Reaction (1) is illustrated in the following manner. Two pi\ + effective-mass combinations can be formed from the final-state particles of Reaction (1); furthermore, for each mass combination the invariant momentum transfer from either projectile or target proton may be considered.…”

Production of the Nucleon Isobars 1236, 1410, 1518, and 1688 MeV in Proton-Proton Collisions at 2.85, 4.55, 6.06, and 7.88 GeV/c

“…Experiments of this type have previously been carried out at various energies and angles at the Cosmotron, 1 ' 2 CERN proton synchrotron, 3-" 5 Bevatron, 6 and alternating-gradient synchrotron. 7 In the present experiment the use of several incident momenta, together with a range of scattering angles for each, allows us to investigate systematically the production of various nucleon isobars as functions of the kinematical variables s and Mna relatively unexplored region. The squared total center-of-mass energy, s, varied from 7.3 (GeV) 2 at the lowest beam momentum to 16.7 (GeV) 2 at the highest.…”