arXiv subjects

T. Sjöstrand

Publications and source records attributed to T. Sjöstrand.

22 records · Page 2Linked to original sources

arXiv1997

Modelling Bose-Einstein correlations at LEP 2

We present new algorithms for simulating Bose-Einstein correlations among final-state bosons in an event generator. The algorithms are all based on introducing Bose-Einstein correlations as a shift of final-state momenta among identical bosons, and differ only in the way energy and momentum conservation is ensured. The benefits and shortcomings of this approach, that may be viewed as a local reweighting strategy, is compared to the ones of recently proposed algorithms involving global event reweighting. We use the new algorithms to improve on our previous study of the effects of Bose-Einstein correlations on the W mass measurement at LEP 2. The intrinsic uncertainty could be as high as 100 MeV but is probably reduced to the order of 30 MeV with realistic experimental reconstruction procedures.

hep-ph↗

arXiv1997

A matching of matrix elements and parton showers

We propose a simple scheme to start a parton-shower evolution description from a given jet configuration in $e^+ e^-$ annihilation events. This allows a convenient combination of the full angular information content of matrix elements with the detailed sub-jet structure of parton showers, and should give a realistic overall description of event properties. Explicit studies with this hybrid approach are presented for the four-jet case, as a simple testing ground of the ideas.

hep-ph↗

arXiv1997

QCD aspects of leptoquark production at HERA

If a leptoquark is produced at HERA as a narrow resonance, various effects tend to broaden the measurable mass distribution considerably. These effects are discussed here, with special emphasis on initial- and final-state QCD radiation. A proper understanding is important to assess the significance of data and to devise strategies for better mass reconstruction.

hep-ph↗

arXiv1996

Transverse Momentum as a Measure of Colour Topologies

Several distinct colour flow topologies are possible in multiparton configurations. A method is proposed to find the correct topology, based on a minimization of the total transverse momentum of produced particles. This method is studied for three-jet $Z^0 \to q\overline{q} g$ and four-jet $W^+W^- \to q_1\overline{q}_2q_3\overline{q}_4$ events. It is shown how the basic picture is smeared, especially by parton-shower activity. The method therefore may not be sufficient on its own, but could still be a useful complement to others, and e.g. help provide some handle on colour rearrangement effects.

hep-ph↗