arXiv subjects
Publications and source records attributed to A. P. Contogouris.
Recently obtained NNLO exact corrections for Higgs and Pseudoscalar Higgs boson production in hadron colliders are compared with approximate ones. As shown before, it is found that there is a range of a proper variable where these corrections differ little.
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.
For processes involving structure functions and/or fragmentation functions, arguments that there is a part that dominates the NLO corrections are briefly reviewed. The arguments are tested against more recent NLO and in particular NNLO calculations.
A complete next-to-leading order calculation of longitudinally polarized heavy quark photoproduction is presented. All results of the purturbative calculation are given in detail. For reactions and energies of interest cross sections differential in the transverse momentum and rapidity of the heavy quark, total cross sections and the corresponding asymmetries are given. Errors in the asymmetries are estimated and the possibility to distinguish between various scerarios of the polarized gluon distribution is discussed. Our results are compared with other related publications.
The results of a next-to-leading order calculation of heavy quark production in longitudinally polarized photon-nucleon collisions are presented. At c.m. energy $\sqrt{S}=10$ GeV, for $\vec γ+\vec p \to c+X$, cross sections differential in the transverse momentum and rapidity of the charmed quark $c$ and the corresponding asymmetries are presented; also, as functions of $\sqrt{S}$, integrated cross sections, $K$-factors and the corresponding asymmetries are given. Errors in the asymmetries are estimated and the possibility to distinguish between three scerarios differing essentially in the polarized gluon distribution is discussed.
Results of our next-to-leading order analytic calculation for longitudinally polarized photoproduction of heavy quarks are presented. Certain differential cross sections and the corresponding asymmetries are computed for energy ranges accessible to CERN and HERA. We argue that determination of the polarized gluon distribution is possible at both places: at HERA certain acceptance cuts are necessary.
Production of large-p_T hadron pairs by polarized photon on a longitudinally polarized proton towards probing the polarized gluon distribution is studied. Resolved photon contributions and the effect of changing the scales are taken into account, and predictions are presented. A very recent experimental result at c.m. energy 7.18 GeV is compared to our predictions extented down to this energy. A proper combination of cross sections is also considered.
Recently determined next-to-leading order sets of polarized parton distributions are used to study large-p_T $\vec{p}\vec{p}\rightarrow γ+X$ at $\sqrt{s}=38, 100 and 500 GeV$. Certain conversion terms, necessary to use the above sets, are determined. It is concluded that, to distinguish between the above sets, planned RHIC experiments should be successful, in particular at c.m. photon pseudorapidity $\simeq 1$, and that a proposed HERA-$\vec{N}$ fixed target experiment should have rather large accuracy at relatively large $x_T (=2p_T/\sqrt{s})$.
Complete analytical results for the production of heavy-quark pairs by polarized and unpolarized photons in next-to-leading order are presented. Two-, three- and two plus three-jet cross sections for total photon spin $J_z=0,\pm 2$ are presented for $b\bar{b}(g)$ production. The 2-jet cross sections are considered as a background to $γγ\rightarrow H^* \rightarrow b\bar{b}$ (standard model). Top production, not too far above threshold, is also considered for $J_z=0,\pm 2$. For both $b$- and $t$-quark production, the higher order QCD corrections are found to be significant.