P. Valin

TOWARDS A BLACKER, EDGIER AND LARGER PROTON

Abstract We show that the preliminary SPS p p collider results strongly suggest that the elastic p p profile becomes centrally more opaque and edgier and increases in range (Blacker, Edgier, Larger or BEL behaviour) compared to the elastic pp profile at the ISR. We use three different methods to quantify our conclusions and estimate their reliability subject to experimental uncertainties.

Forward scattering amplitudes in semi-hard QCD☆

Abstract We argue that the observation by UA4 of a high energy ρ value (real-to-imaginary ratio of the forward p p amplitude) in excess of what had been predicted is accommodated by QCD. At s ≅0.1−1 TeV , typical hadron collisions become semi-hard and therefore calculable in perturbative QCD. An “effective” threshold develops in this energy region as a result of the “exploding” gluon content of the proton. We associate the increase with energy of the total cross section with this threshold and show that it will also result in a rapid increase of ρ over and above what is expected from models which do not take into account this qualitative change in the structure of hadrons. The first signature of this “threshold” has arguably been seen by UA1 through the discovery of the minijet phenomena. We predict substantially higher cross section and ρ values at the Tevatron collider and the SSC.

The inelastic differential cross section in impact parameter space at ISR energies

Abstract Implications of increasing total cross sections and diffractive structures at CERN-ISR on the inelastic differential cross section in impact parameter space are discussed. It is a Gaussian plus a small “edge” correction and its increase through the ISR energies is peripheral as compared to the overall region of inelastic collisions, while inside this region it remains relatively constant and below the unitarity bound.

Does the proton look BEL at super-t and supercolliders?

Abstract When its energy increases from the CERN ISR to the collider, the proton turns BEL (Blacker, Edgier, Larger)—it seems to be tending, slowly, toward the step-function profile of the famous Froissart-Martin bound. We discuss this BEL effect in light of the final UA4-data, and present some diffraction-theoretical predictions for future measurements, especially at supercolliders.

On the validity of Martin's real-part formula

Abstract The real-part dynamics of the proton-proton/antiproton scattering amplitude within the framework of dispersive diffraction theory is presented, from 0.02 through 0.54 to 40 TeV. Specific results are: (1) the explicit corrections to Martins still useful real-part formula; (2) the correlation between cross-over and vanishing of the real part; (3) dip dynamics; (4) the objective nature of these results.

The gluon structure of high energy hadrons and their interactions

Abstract We argue that the production of gluon jets, a rare occurrence at low energy, becomes a feature of average hadron collisions at very high energies, √s > 1 TeV. This inspires a model where hadron interactions are mediated by semi-hard gluons rather than valence quarks. We calculate forward scattering as the shadow of the large inelastic cross sections associated with gluon jets. In this type of model the total cross section and event structure at future hadron colliders could be very different from what is routinely anticipated.

Gluon interactions and diffraction

Abstract We study the relationship between gluon-gluon scattering and inelastic pp and p p processes and their shadow, the elastic channel. At values of ∝s in the neighborhood of 1 TeV, typical hadron collisions become semi-hard and calculable using QCD. The rapidly increasing gluon content of the hadron results in an increasing total cross section and a relatively large ratio of real to imaginary forward scattering amplitude.