Light-cone Dynamics Research Articles

Analysis of the 8� proton spectrum fromd+p collisions at 9 GeV/c

The 8° proton spectrum from d+p collisions at 9 GeV/c is described on the basis of the impulse approximation. We apply the Paris deuteron wave function and take the various inelastic channels into account. This approach is compared to results from light-cone dynamics. The two variants lead to contradictory conclusions concerning the origin of the high-momentum tail of the spectrum.

Second-class axial-vector current of the nucleon in a relativistic constituent quark model

The nucleon is described as a relativistic three-quark system in light-cone dynamics. One of its three wave function invariants, I 1, is shown to generate a second-class axial-vector current. When the transverse quark motion is negligible I 1 is not present. For some separable, scalar, three-body confinement interactions the I 1 admixture also remains small.

Comments on covariant formulations of string theories

We clarify the role of the critical dimension in some covariant formulations of string theory. The action for the free string proposed by Banks and Peskin is shown to be equivalent to the light-cone dynamics of Goddard, Goldstone, Rebbi, and Thorn if and only if the dimension of spacetime is critical and α 0=1. If these conditions are not satisfied, the action principle does not imply the physical state conditions in a class of completely fixed light-cone gauges.

Relativistic correction to the deuteron magnetic moment and angular condition

The relativistic correction (RC) to the deuteron magnetic moment is calculated using the light-cone dynamics. The restrictions imposed by the angular condition on the electromagnetic current operator of the deuteron are discussed in detail. It is shown that the additive model for the current operator of interacting constituents is consistent with the angular condition only for the two first terms of the expansion of the “good” current component j + = 1 2 (j 0 + j z ) in powers of the momentum transfer q. The RC to μ d is expressed through the matrix element of the “good” component j + and is found to be equal to (0.6–0.8) × 10 −2 e h ̵ /2m p c for realistic NN potentials. Taking account of RC decreases essentially the discrepancy between the theoretical and experimental values of μ d. Possible solutions of the angular condition for squared q-terms of the j + current component are also discussed.