Related papers: Quark spin effects in $e^+e^-$ annihilation: a Mon…
Some results highlighting the status of a new version of a cluster fragmentation model for the Monte Carlo event generator Sherpa are presented. In its present version this model is capable of simulating e+e- annihilation events into…
We calculate the spin density matrix of the vector meson produced in e+e- annihilation at Z^0 pole. We show that the data imply a significant polarization for the antiquark which is created in the fragmentation process of the polarized…
An improved description of four-pion production in electron-positron annihilation and in tau lepton decays is presented. The model amplitude is fitted to recent data from BaBar which cover a wide energy range and which were obtained…
We introduce spin-1/2 baryons in the string+${}^3P_0$ model of hadronization, previously restricted to the production of pseudoscalar and vector mesons. Baryons are modeled as quark-diquark bound states and baryon production is described by…
The multiplicity of heavy quarks from gluon splitting in e+e- annihilation has now been theoretically calculated and experimentally measured at LEP. However, the experimental measurement requires theoretical input for the shape of the…
The Fragmentation Functions is one of the non-perturbative components of the QCD factorization theorem. They represents the probability of a parton carrying a fraction z of momentum to form into a particular kind of hadron. In this work, we…
In the two papers published recently, we apply collinear expansion to both inclusive ($e^+ e^- \to h+X$) and semi-inclusive ($e^+ e^- \to h + \bar q + X$) hadron production in $e^+ e^-$ annihilation to derive a formalism suitable for a…
We study, at leading order in the large number of colours expansion and within the Resonance Chiral Theory framework, the odd-intrinsic-parity $e^+ e^- \rightarrow \pi^+ \pi^- (\pi^0, \eta)$ cross-sections in the energy regime populated by…
An elementary recursive model accounting for the quark spin in the fragmentation of a quark into mesons is presented. The quark spin degree of freedom is represented by a two-components spinor. Spin one meson can be included. The model…
We apply collinear expansion to inclusive hadron production in $e^+e^-$ annihilation and derive a formalism suitable for systematic study of leading as well as higher twist contributions to fragmentation functions at the tree level. We make…
Three studies on six-fermion production processes are presented, in which the production of an intermediate-mass Higgs boson, the top-quark physics and the analysis of possible anomalous quartic gauge couplings are considered. A Monte Carlo…
It was shown that at typical energies and luminosities of an $e^+e^-$ linear collider one can observe a significant suppression of fluctuations of the number of gluons in small angular regions. This property of jets is expected in $e^+e^-$…
The charged particles multiplicity distribution in the KNO form is discussed in processes of $e^+e^-$ annihilation at energies $\sqrt{s}$ 14 -- 206.2 GeV. The experimental data are compared to data, obtained with Monte Carlo simulation in…
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…
Recent measurements, in particular those on $\Lambda$ polarization and spin alignment of vector mesons in $e^+e^-$ annihilation at LEP, and those on the azimuthal asymmetry at HERA, have attracted much attention on the spin effects in high…
We present EEXICC, a Monte Carlo event generator designed to simulate the production of doubly heavy baryons ($\Xi_{cc}$, $\Xi_{bc}$, and $\Xi_{bb}$) via $e^+e^-$ annihilation. Based on nonrelativistic QCD effective theory, the generator…
We study string fragmentation in high multiplicity proton-proton collisions in a model where the string tension fluctuates. These fluctuations produce exponential pion spectra which are fitted to the transverse momentum distributions of…
A generator with $\alpha^2$ order radiative correction effects, including both the initial state radiative corrections and the photon vacuum polarization corrections, is built for the full simulation of $e^+e^- \to hadrons $ in cross…
The fragmentation of an unpolarized quark into a transversely polarized spin-1/2 particle is studied in the framework of a simple model. Special attention is payed to the gluon exchange which is incorporated in the gauge link of the…
An azimuthal dependence of pions produced in polarized Deep Inelastic Scattering, gamma^* - p(transv. polarized) -> pion + X, has been recently observed and might be related to the so-called Collins effect. We discuss in details, for a…