Dokshitzer-Gribov-Lipatov-Altarelli-Parisi Evolution and the Renormalization Group Improved Yennie-Frautschi-Suura Theory in QCD

We show that the recently derived renormalization group improved Yennie-Frautschi-Suura (YFS) exponentiation of soft $(k_o\to 0)$ gluons in QCD is fully compatible with the usual Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution of the structure functions of hadrons in the respective hadron-hadron hard interactions. We show how to implement the YFS exponentiation without double or over counting effects already implied by the DGLAP equation. In this way, we arrive at a theory which allows for the development of realistic, multiple gluon Monte Carlo event generators for hard hadron-hadron scattering processes in which the DGLAP evolved structure functions are correctly synthesized with the respective YFS exponentiated soft gluon effects in a rigorous way.Comment: 10 pages, 0 figures, 1 Latex fil

YFS MC Approach to QCD Soft Gluon Exponentiation

We present two things in this discussion. First, we develop and prove the theory of the extension of the YFS Monte Carlo approach to higher order SU_{2L} x U_1 radiative corrections to the analogous higher order QCD radiative corrections. Contact is made with other pioneering soft gluon resummation theories in the literature. Second, semi-analytical results and preliminary explicit Monte Carlo data are presented for the specific example of the processes p-bar p -> t-bar t +n(G)+X at FNAL energies, where G is a soft gluon and the respective event generator, ttp1.0, features realistic, event-by-event simulation of multiple, soft, finite p_T gluon effects in which the infrared singularities are canceled to all orders in alpha_s. We comment briefly on the implications of our results on the CDF/D0 observations and on their possible applications to RHIC physics and to LHC physics.Comment: 16 pages, 2 figs., 2002 Epiphany Con

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

The Monte Carlo Program KORALZ, for the Lepton or Quark Pair Production at LEP/SLC Energies -- From version 4.0 to version 4.04

Brief information on new features of KORALZ version 4.04 with respect to version 4.0 is given. The main difference is that the new version could be used at LEP2 energies, i.e. up to 240 GeV centre-of-mass system energy. The possibility to switch on different classes of anomalous couplings is also included.Comment: 1+6 page

The Precision Monte Carlo Event Generator KK For Two-Fermion Final States In e+e- Collisions

We present the Monte Carlo event generator KK version 4.13 for precision predictions of the Electroweak Standard Model for the process $e^+e^-\to f\bar{f} +n\gamma$, $f=\mu,\tau,d,u,s,c,b$ at centre of mass energies from $\tau$ lepton threshold to 1TeV, that is for LEP, SLC, future Linear Colliders, $b,c,\tau$-factories etc. Effects due to photon emission from initial beams and outgoing fermions are calculated in QED up to second order, including all interference effects, within Coherent Exclusive Exponentiation (CEEX), which is based on Yennie-Frautschi-Suura exponentiation. Electroweak corrections are included in first order, with higher order extensions, using the DIZET 6.x library. Final state quarks hadronize according to the parton shower model using JETSET. Beams can be polarized longitudinally and transversely. Decay of the tau leptons is simulated using the TAUOLA library, taking into account spin polarization effects as well. In particular the complete spin correlations density matrix of the initial state beams and final state tau's is incorporated in an exact manner. Effects due to beamstrahlung are simulated in a realistic way. The main improvements with respect to KORALZ are: (a) inclusion of the initial-final state QED interference, (b) inclusion of the exact matrix element for two photons, and (c) inclusion of the transverse spin correlations in $\tau$ decays (as in KORALB).Comment: Source code available from http://home.cern.ch/jadac

Coherent Exclusive Exponentiation of 2f Processes in e+e- Annihilation

In the talk we present the Coherent Exclusive Exponentiation (CEEX) which is implemented in the KK MC event generator for the process e+e- to f bar f +n gamma, f=mu,tau,d,u,s,c,b for center of mass energies from tau lepton threshold to 1TeV, that is for LEP1, LEP2, SLC, future Linear Colliders, b,c,tau-factories etc. We will attempt a short discussion of the theoretical concepts necessary in our approach, in particular the relations between the rigorous calculation of spin amplitudes (perturbation expansion), phase space parametrisation and exponentiation. In CEEX effects due to photon emission from the initial beams and outgoing fermions are calculated in QED up to second-order, including all interference effects. Electroweak corrections are included in first-order, at the amplitude level. The beams can be polarised longitudinally and transversely, and all spin correlations are incorporated in an exact manner. Precision predictions, in particular the photon emission at LEP2 energies, are also shown.Comment: latex 9 pages, including 6 eps tables/figure