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Karol Kolodziej

Publications and source records attributed to Karol Kolodziej.

29 records · Page 2Linked to original sources
arXiv2005

One-loop electroweak factorizable corrections for the Higgsstrahlung at a linear collider

We present standard model predictions for a four fermion reaction e+ e- -> mu+ mu- bar_b b being one of the best detection channels of a low mass Higgs boson produced through the Higgsstrahlung mechanism at a linear collider. We include leading virtual and real QED corrections to all the lowest order Feynman diagrams of e+ e- -> mu+ mu- bar_b b and the complete O(alpha) electroweak corrections to the Z-Higgs production and to the Z and Higgs boson decay widths in the double pole approximation.

hep-ph↗
arXiv2004

ee4fgamma, A program for e+e- -> 4f, 4fgamma with nonzero fermion masses

A computer program ee4fgamma for calculating cross sections of any four fermion final state of e+e--annihilation at high energy and the corresponding bremsstrahlung reaction that is possible in the framework of the Standard Model is presented. As the fermion masses are arbitrary, the cross sections can be computed without any collinear cut, the on-shell top quark production can be studied and the Higgs boson exchange can be incorporated in a consistent way. The program can be used as a Monte Carlo generator of unweighted events as well.

hep-ph↗
arXiv2003

Studying top quark pair production at a linear collider with a program 'eett6f'

Some features of a program 'eett6f' for top quark pair production and decay into six fermions at linear colliders are discussed. Lowest order standard model predictions for cross sections of some six fermion channels and for the top quark decay width are confronted with the predictions obtained within a model with an anomalous Wtb coupling. The question of wether non doubly resonant background can easily be reduced by imposing kinematical cuts is addressed.

hep-ph↗
arXiv2002

eett6f v. 1.0, A program for top quark pair production and decay into 6 fermions at linear colliders

The first version of a computer program "eett6f" for calculating cross sections of e+e- -> 6 fermions processes relevant for a t\bar{t}-pair production and decay at centre of mass energies typical for linear colliders is presented. "eett6f v.~1.0" allows for calculating both the total and differential cross sections at tree level of the Standard Model. The program can be used as the Monte Carlo generator of unweighted events as well.

hep-ph↗
arXiv2002

Top quark pair production and decay into 6 fermions at linear colliders

The production of a t\bar{t}-pair and its decay into a 6 fermion final state of different flavours in e+e- annihilation at centre of mass energies typical for linear colliders is analyzed in the framework of the Standard Model. The results of calculation based on exact matrix elements at the tree level and full 6 particle phase space are compared with a few different approximations. It is shown that the effects related to off-shellness of the t\bar{t}-pair and background contributions are sizable both in the continuum and at the threshold.

hep-ph↗
arXiv2001

Top quark production in e+e- annihilation

We analyze the four-fermion reactions e+e- -> 4f containing a single top quark and three other fermions, a possible decay product of the resonant anti-top quark, in the final state. This allows us to estimate the contribution of the nonresonant Feynman graphs and effects related to the off mass shell production and decay of the top quark. We test the sensitivity of the total cross section at centre of mass energies in the t tbar threshold region and far above it to the variation of the top quark width. We perform calculation in an arbitrary linear gauge in the framework of the Standard Model and discuss an important issue of gauge symmetry violation by the constant top quark width.

hep-ph↗
arXiv1995

Production of B_c Mesons in Photon-Photon and Hadron-Hadron Collisions

We discuss two-photon and hadronic production of $B_c$ mesons in nonrelativistic bound state approximation and to lowest order in the coupling constants $α$ and $α_s$. It is shown that in photon-photon collisions, heavy quark fragmentation is dominated by recombination of $\bar b$ and $c$ quarks up to the highest accessible transverse momenta. In contrast, in hadroproduction, which at high energies mainly involves gluon--gluon collisions, the fragmentation mechanism dominates at transverse momenta $p_T > m_{B_c}$, providing a simple and satisfactory approximation of the complete $O(α_s^4)$ results in the high-$p_T$ regime. Contradictions in previous publications on hadroproduction of $B_c$ mesons are clarified. We also present predictions for cross sections and differential distributions at present and future accelerators.

hep-ph↗
arXiv1994

Standard Model Predictions for Weak Boson Pair Production in E-E- Scattering

We study polarized $e^-e^-$ scattering into $\WW$, $\WZ$ and $\ZZ$ final states within the framework of the standard model of electroweak interactions. These mechanisms for producing pairs of weak gauge bosons are potential backgrounds to new reactions beyond the realm of the standard model. At a centre-of-mass energy of 500 GeV the total cross sections are calculated to be 2.5, 9.4 and 1.0 fb, respectively, for unpolarized beams. The energy behaviour of the cross sections as well as particularly interesting differential distributions are presented and the topology of the final states is discussed.

hep-ph↗