Next-to-Leading Order QCD Corrections to the Polarized Photoproduction of Heavy Flavors

We present a calculation of the next-to-leading order (O(alpha_s^2 alpha)) QCD corrections to heavy flavor photoproduction with longitudinally polarized beams. We apply our results to study the longitudinal spin asymmetry for the total charm quark production cross section which will be utilized by the forthcoming COMPASS experiment at CERN to obtain first direct information on the polarized gluon density Delta g. We also briefly discuss the main theoretical uncertainties inherent in this calculation. In particular we demonstrate that the factorization scale dependence is considerably reduced in next-to-leading order.Comment: 18 pages, LaTeX, 4 figures, uses epsfig and amssymb style

Small x resummations confronted with F_2(x,Q^2) data

It has been observed recently that a consistent LO BFKL gluon evolution leads to a steep growth of F_2(x,Q^2) for x -> 0 almost independently of Q^2. We show that current data from the DESY HERA collider are precise enough to finally rule out a pure BFKL behaviour in the accessible small x region. Several attempts have been made by other groups to treat the BFKL type small x resummations instead as additions to the conventional anomalous dimensions of the successful renormalization group ``Altarelli-Parisi'' equations. We demonstrate that all presently available F_2 data, in particular at lower values of Q^2, can not be described using the presently known NLO (two-loop consistent) small x resummations. Finally we comment on the common reason for the failure of these BFKL inspired methods which result, in general, in too steep x-dependencies as x -> 0.Comment: Revised, to be published in Phys. Lett. B., 18 pages, LaTeX2e, 3 figures, uses amssymb and epsfig style

Prospects of Open Charm Production at GSI-FAIR and J-PARC

We present a detailed phenomenological study of the prospects of open charm physics at the future $\bar{p}p$ and $pp$ facilities GSI-FAIR and J-PARC, respectively. In particular, we concentrate on differential cross sections and the charge and longitudinal double-spin asymmetries at next-to-leading order accuracy. Theoretical uncertainties for the proposed observables are estimated by varying the charm quark mass and the renormalization and factorization scales.Comment: 11 pages, 13 figure

Next-to-leading order QCD corrections to the polarized hadroproduction of heavy flavors

We present the complete next-to-leading order QCD corrections to the polarized hadroproduction of heavy flavors which soon will be studied experimentally in polarized pp collisions at the BNL Relativistic Heavy Ion Collider (RHIC) in order to constrain the polarized gluon density Δg. It is demonstrated that the dependence on unphysical renormalization and factorization scales is strongly reduced beyond the leading order. The sensitivity of the charm quark spin asymmetry to Δg is analyzed in some detail, including the limited detector acceptance for leptons from charm quark decays at the BNL RHIC.Ingo Bojak and Marco Stratman

Everything you wanted to ask about EEG but were afraid to get the right answer

We answer several important questions concerning EEG. We also shortly discuss importance of nonlinear methods of contemporary physics in EEG analysis. Basic definitions and explanation of fundamental concepts may be found in my previous publications in NBP

Heavy quark production as sensitive test for an improved description of high energy hadron collisions

QCD dynamics at small quark and gluon momentum fractions or large total energy, which plays a major role for HERA, the Tevatron, RHIC and LHC physics, is still poorly understood. For one of the simplest processes, namely bottom-antibottom production, next-to-leading-order perturbation theory fails. We show that the combination of two recently developed theoretical concepts, the k_perp-factorization and the next-to-leading-logarithmic-approximation BFKL vertex, gives perfect agreement with data. One can therefore hope that these concepts provide a valuable foundation for the description of other high energy processes.Comment: RevTeX, 4 pages, 7 figures titel and abstract changed, several formulations modified in the text, 1 figure droppe

Collinear Subtractions in Hadroproduction of Heavy Quarks

We present a detailed discussion of the collinear subtraction terms needed to establish a massive variable-flavour-number scheme for the one-particle inclusive production of heavy quarks in hadronic collisions. The subtraction terms are computed by convoluting appropriate partonic cross sections with perturbative parton distribution and fragmentation functions relying on the method of mass factorization. We find (with one minor exception) complete agreement with the subtraction terms obtained in a previous publication by comparing the zero-mass limit of a fixed-order calculation with the genuine massles results in the MSbar scheme. This presentation will be useful for extending the massive variable-flavour-number scheme to other processes.Comment: 29 pages, 17 figures include