Related papers: The Four-Jet Rate in e+e- Annihilation
For many observables, the most difficult part of a single logarithmic resummation is the analytical treatment of the observable's dependence on multiple emissions. We present a general numerical method, which allows the resummation…
Charged particle energy spectra in e+e- annihilation are compared with the analytical predictions from the QCD evolution equation in the Modified Leading Log Approximation. With the nonperturbative initial condition shifted down to…
We present next-to-leading order corrections in the leading colour approximation for jet rates in electron-positron annihilation up to seven jets. The results for the two-, three-, and four-jet rates agree with known results. The NLO jet…
We perform a comparison of two jet clusterization algorithms. The first one is the standard Durham algorithm and the second one is a global optimization scheme, Deterministic Annealing, often used in clusterization problems, and adapted to…
We present the complete twist-4 results for the semi-inclusive annihilation process $e^+ +e^- \to h+ \bar q+X$ at the tree level of perturbative quantum chromodynamics. The calculations are carried out by using the formalism obtained by…
We present the QCD analysis of D-parameter distribution in near-to-planar 3-jet e+e- annihilation events. We derive the all-order resummed perturbative prediction and the leading power suppressed non-perturbative corrections both to the…
The current status of theoretical work and experimental analyses on power corrections in QCD for e+e- annihilation will be reviewed. Measurements of the number of active quark flavours n_f and the QCD colour factors C_A and C_F derived from…
Perturbative calculations at next-to-next-to-leading order for multi-particle final states require a method to cancel infrared singularities. I discuss the subtraction method at NNLO. As a concrete example I consider the leading-colour…
Perturbative QCD analysis is presented of the cumulative out-of-plane momentum distribution in the near-to-planar e+e- annihilation events, K_out << Q. In this kinematical region multiple gluon radiation effects become essential. They are…
We present a QCD analysis of the cumulative out-of-event-plane momentum distribution in DIS process with emission of high p_t jets. We derive the all-order resummed result to next-to-leading accuracy and estimate the leading power…
We calculate the mean number of subjets in quark and gluon jets in the final state of e^+e^- annihilation. Since `quark' and `gluon' jets are scheme-dependent objects, we stress the importance of using the same definition as in experimental…
We discuss a calculation of the next-to-leading order QCD corrections to the process $e^+e^-\to 3$ jets with massive quarks, and show numerical results for the three jet fraction and the differential two jet rate.
We discuss some important issues concerning multiplicities in quark and gluon jets in e+e- annihilation. In QCD the properties of a jet in general depend on two scales, the energy and virtuality of the jet. Frequently theoretical…
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…
In coalescing ballistic annihilation, infinitely many particles move with fixed velocities across the real line and, upon colliding, either mutually annihilate or generate a new particle. We compute the critical density in symmetric…
We compute production rates for two, three, four and five jets in electron-positron annihilation at the third order in the QCD coupling constant. At this order, three-jet production is described to next-to-next-to-leading order (NNLO) in…
We discuss the orientation of e+e- -> q qbar g events in terms of the polar and azimuthal angles of the event plane w.r.t. the electron beam direction. We define an asymmetry of the azimuthal-angle distribution, which, along with the…
In this thesis we describe the calculation of the process e+ e- --> Z/gamma -> Q Qbar + X, where Q is a heavy quark, X is anything else at order alpha_s^2.
The longitudinal (e,e') response function of 4He is calculated precisely with full final state interaction. The explicit calculation of the four-body continuum states is avoided by the method of integral transforms. Precision tests of the…
Recently, interest has developed in the distribution of interjet energy flows, with for example the leading-log calculation of the highly non-trivial colour structure of primary emissions in 4-jet systems. Here we point out however that at…