QED X QCD Exponentiation: Shower/ME Matching and IR-Improved DGLAP Theory at the LHC

We discuss the elements of QED X QCD exponentiation and its interplay with shower/ME matching and IR-improved DGLAP theory in precision LHC physics scenarios. Applications to single heavy gauge boson production at hadron colliders are illustrated.Comment: 5 pages, 1 figure; presented by B.F.L. Ward at ICHEP0

New Approach to Parton Shower MC's for Precision QCD Theory: HERWIRI1.0(31)

By implementing the new IR-improved Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-Callan-Symanzik (DGLAP-CS) kernels recently developed by one of us in the HERWIG6.5 environment we generate a new MC, HERWIRI1.0(31), for hadron-hadron scattering at high energies. We use MC data to illustrate the comparison between the parton shower generated by the standard DGLAP-CS kernels and that generated by the new IR-improved DGLAP-CS kernels. The interface to MC@NLO, MC@NLO/HERWIRI, is illustrated. Comparisons with FNAL data and some discussion of possible implications for LHC phenomenology are also presented.Comment: 24 pages, 10 figures; published versio

QED \otimes QCD Threshold Corrections at the LHC

We use the theory of YFS resummation to compute the size of the expected resummed soft radiative threshold effects in precision studies of heavy particle production at the LHC, where accuracies of 1 percent are desired in some processes. We find that the soft QED threshold effects are at the level of 0.3 percent whereas the soft QCD threshold effects enter at the level of 20 percent and hence both must be controlled to be on the conservative side to achieve such goals.Comment: 8 pages, no figures; improved text; improved refs. and tex

The Virtual Correction to Bremsstrahlung in High-Energy e+ e- Annihilation: Comparison of Exact Results

We have compared the virtual corrections to single hard bremsstrahlung as calculated by S. Jadach, M. Melles, B.F.L. Ward and S.A. Yost to several other expressions. The most recent of these comparisons is to the leptonic tensor calculated by J.H. Kuhn and G. Rodrigo for radiative return. Agreement is found to within a part in 10^5 or better, as a fraction of the Born cross section, for most of the range of photon energies. The massless limits have been shown to agree analytically to NLL order.Comment: 7 pages, 2 figures. Presented by S.A. Yost at ICHEP 2004, International Conference on High Energy Physics, Beijing, August 16-22, 200

Exact Differential O(alpha**2) Results for Hard Bremsstrahlung in e+e- Annihilation to 2f At and Beyond LEP2 Energies

We present the exact O(alpha) correction to the process e+ e- -> f f-bar + gamma, f neq e, for ISR oplus FSR at and beyond LEP2 energies. We give explicit formulas for the completely differential cross section. As an important application, we compute the size of the respective sub-leading corrections of O(alpha L) to the f f-bar cross section, where L is the respective big logarithm in the renormalization group sense so that it is identifiable as L = ln |s|/m_e^2 when s is the squared e+e- cms energy. Comparisons are made with the available literature. We show explicitly that our results have the correct infrared limit, as a cross-check. Some comments are made about the implementation of our results in the framework of the Monte Carlo event generator KK MC.Comment: 26 pages, 5 figs.;improved discussion, figs. and definitions;corrected misprint