Approximate Next-to-Leading Order and Next-to-Next-to-Leading Order Corrections

For processes involving structure functions and/or fragmentation functions, arguments that, over a range of a proper kinematic variable, there is a part that dominates the next-to-leading order (NLO) corrections are briefly reviewed. The arguments are tested against more recent NLO and in particular complete next-to-next-to-leading order (NNLO) calculations. A critical examination of when these arguments may not be useful is also presented.Comment: 8 pages and 4 figure

A Model for the Color Glass Condensate Versus Jet Quenching

A model for the Color Glass Condensate as opposed to jet quenching is proposed for the explanation of the presently available RHIC data. Good fits to these data are presented. A clear way to distinguish between the two possible explanations is also given.Comment: 3 pages, 1 figur

Regge poles and inelastic scattering at high energies

The Regge pole hypothesis is applied to some inelastic processes at high energies. Particular attention is given to production of pion-nucleon resonances N* in the reaction N+N→N+N*. Data on production of the I=1/2 resonances are interpreted in terms of exchange of the "Pomeranchuk" Regge pole which is believed to be responsible for the diffraction peaks in elastic reactions, and production of the 3-3 resonance is interpreted in terms of exchange of the pion Regge pole. The prediction is obtained that production and decay of the I=1/2 resonances provides secondary pions and neutrons with energies that rise proportionally to the incident proton energy—a result of interest in connection with the secondary beams in future accelerators

Diphoton Production at Hadron Colliders and New Contact Interactions

We explore the capability of the Tevatron and LHC to place limits on the possible existence of flavor-independent $q \bar q \gamma\gamma$ contact interactions which can lead to an excess of diphoton events with large invariant masses. Assuming no departure from the Standard Model is observed, we show that the Tevatron will eventually be able to place a lower bound of 0.5-0.6 TeV on the scale associated with this new contact interaction. At the LHC, scales as large as 3-6 TeV may be probed with suitable detector cuts and an integrated luminosity of $100 fb^{-1}$.Comment: LaTex, 12pages plus 5 figures(available on request), SLAC-PUB-657

Aspects of four-jet production in polarized proton-proton collisions

We examine the intrinsic spin-dependence of the dominant $gg \rightarrow gggg$ subprocess contribution to four-jet production in polarized proton-proton collisions using helicity amplitude techniques. We find that the partonic level, longitudinal spin-spin asymmetry, $\hat{a}_{LL}$, is intrinsically large in the kinematic regions probed in experiments detecting four isolated jets. Such events may provide another qualitative or semi-quantitative test of the spin-structure of QCD in planned polarized $pp$ collisions at RHIC.Comment: 9 pages, LaTeX, 2 uuencoded postscript files attache