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A. Leike

Publications and source records attributed to A. Leike.

30 records · Page 2Linked to original sources
arXiv1996

Z' Search in e+e- Annihilation

Expectations for constraints on extra Z bosons are derived for LEP 2 and future linear e+e- colliders. For typical GUTs, a Z' with M_{Z'} \le 3 to 6 \sqrt{s} may cause observable effects. The Z' discovery limits are dominated by statistical errors. However, if a Z' signal is observed, the discrimination between different models becomes much worse if systematic errors are taken into account. Discrimination between models is possible for M_{Z'} < 3 \sqrt{s}. A determination of Z' f \bar f couplings independently of models becomes attractive with future colliders. Anticipated bounds are determined.

hep-ph↗
arXiv1996

Four fermion final states in $e^+e^-$ annihilation

The present status of calculations of four fermion final states is reviewed. Higher order problems arising there are pointed out. Special attention is paid to results obtained in the semi-analytical approach and their limitations and perspectives.

hep-ph↗
arXiv1996

Z' Physics

The limits on extra neutral gauge bosons, which could be reached at LEP2, are reviewed. Exclusion and discovery limits are discussed for f\bar f and WW production.

hep-ph↗
arXiv1996

Z' Constraints from e+e- to f fbar at NLC

Constraints on extra neutral gauge bosons are obtained from $e^+e^-\rightarrow f\bar f$ at NLC energies. Model independent limits on the $Z'f\bar f$ couplings and lower limits on the $Z'$ mass are discussed. Typical GUTs with $M_{Z'}$ up to (3 -- 6) $\sqrt{s}$ can be excluded. A distinction between different GUT scenarios is possible if $M_{Z'}\le 3\sqrt{s}$. Radiative corrections give only small changes to the $Z'$ exclusion limits provided that appropriate cuts are applied. %The inclusion of systematic errors leads to slightly worse results for %$M_{Z'}^{lim}$.

hep-ph↗
arXiv1996

GENTLE/4fan - A package of Fortran programs for the description of e+ e- annihilation into four fermions

We describe the program package gentle/4fan, which consists of the Fortran codes gentle\_4fan.f, 4fan.f, and gentle\_nc\_qed.f and is devoted to the description of e+ e- annihilation into four fermions. The codes are based on the semi-analytical approach. Initial state QED corrections are taken into account. The program versions, which are described here were used in the 1995 workshop `Physics at LEP~2'.

hep-ph↗
arXiv1996

Semi-Analytical Approach to Off-Shell W and Z Pair Production

We give a short review of the results for four fermion production, which have been obtained by the semi-analytical approach. The angular degrees of freedom (typically five or more) are integrated over analytically while the integrations over invariant fermion pair masses (typically two or more) remain to be performed by numerical methods. In addition to doubly resonating cross sections from virtual two boson production, QED corrections and background contributions were determined. However, a large variety of final state topologies has not been treated so far.

hep-ph↗
arXiv1996

Higgs Physics at LEP2

In this report we review the prospects for Higgs physics at LEP2. The theoretical aspects and the phenomenology of Higgs particles are discussed within the Standard Model (SM) and the Minimal Supersymmetric Standard Model (MSSM). The experimental search techniques are described and the discovery limits for Higgs bosons in the LEP2 energy range are summarized. In addition, opportunities of detecting Higgs particles in non-minimal extensions of the SM and the MSSM are investigated.

hep-ph↗
arXiv1994

Production Mechanisms for $B_c$ Mesons in Photon--Photon Collisions

Using photon-photon collisions as a particularly transparent study case we investigate the production mechanisms for $B_c$ mesons. In nonrelativistic approximation and to $O(α^2α_s^2)$ it is shown that recombination of $\bar{b}$- and $c$-quarks dominates by far over $\bar{b}$ and $c$ fragmentation. This dominance persists up to the highest accessible transverse momenta and leads to distributions in energy which differ completely from the spectra expected on the basis of the fragmentation functions. For processes in which a $b \bar{b}$-pair is radiated from a primary $c$-quark, the fragmentation description is found to be inadequate. We anticipate important implications of these results for hadronic production of heavy quark resonances. Using realistic photon spectra we predict two-photon production rates for $B_c$ and $B_c^*$ at present and future $e^+e^-$-machines.

hep-ph↗
arXiv1994

Production of Heavy Bound States at LEP and Beyond

We describe some characteristic properties of $B_c$ mesons and discuss the production and the prospects of detection in $e^+ e^-$, $γγ$, and $\bar pp/pp$ collisions. The production mechanisms considered here also play an important role in charmonium and bottomonium production.

hep-ph↗
arXiv1994

Semi-Analytical Approach to Higgs Production at LEP 2

The cross-section for the reaction $e^+e^- \rightarrow b\bar{b}μ^+μ^-$ is calculated with a semi-analytical integration of the phase space. Compact formulae are obtained for the total cross section and for invariant mass distributions of the $μ^+μ^-$ and $b\bar{b}$ pairs. The background diagrams to $ZH$ production yield analytically cumbersome but numerically small contributions. The numerical results are compared with those from a Monte Carlo approach.

hep-ph↗
arXiv1994

Model-Independent $Z'$ Limits from Electron-Electron Collisions

Model independent constraints on the mass of an extra neutral gauge boson and its couplings to charged leptons are given for the $e^-e^-$ option of a future linear collider. Analytic exclusion limits are derived in the Born approximation. The results are compared with those of the $e^+e^-$ mode. The influence of radiative corrections is discussed.

hep-ph↗