| 1. |
- Friberg, C., et al.
(författare)
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QCD aspects of leptoquark production at HERA
- 1997
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Ingår i: Physics Letters B. - 0370-2693. ; 403:3-4, s. 329-334
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Norrbin, E., et al.
(författare)
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Drag effects in charm photoproduction
- 1999
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Ingår i: Monte Carlo generators for HERA physics. Proceedings, Workshop, Hamburg, Germany, 1998-1999. ; , s. 506-511
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Norrbin, E., et al.
(författare)
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Production and hadronization of heavy quarks
- 2000
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 17:1, s. 137-161
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Tidskriftsartikel (refereegranskat)abstract
- Heavy long-lived quarks, i.e. charm and bottom, are frequently studied both as tests of QCD and as probes for other physics aspects within and beyond the standard model. The long lifetime implies that charm and bottom hadrons are formed and observed. This hadronization process cannot be studied in isolation, but depends on the production environment. Within the framework of the string model, a major effect is the drag from the other end of the string that the c/b quark belongs to. In extreme cases, a small-mass string can collapse to a single hadron, thereby giving a non-universal flavor composition to the produced hadrons. We here develop and present a detailed model for the charm/bottom hadronization process, involving the various aspects of string fragmentation and collapse, and put it in the context of several heavy-flavor production sources. Applications are presented from fixed-target to LHC energies.
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| 4. |
- Norrbin, E., et al.
(författare)
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Production mechanisms of charm hadrons in the string model
- 1998
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 442:1-4, s. 407-416
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Tidskriftsartikel (refereegranskat)abstract
- In the hadroproduction of charm in the context of string fragmentation, the pull of a beam remnant at the other end of a string may give a charm hadron more energy than the perturbatively produced charm quark. The collapse of a low-mass string to a single hadron is the extreme case in this direction, and gives rise to asymmetries between charm and anticharm hadron spectra. We study these phenomena, and develop models that describe the characteristics not only of the charm hadrons but also of the associated event.
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| 5. |
- Norrbin, E., et al.
(författare)
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QCD radiation off heavy particles
- 2001
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Ingår i: Nuclear Physics B. - 0550-3213. ; 603:1-2, s. 297-342
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Tidskriftsartikel (refereegranskat)abstract
- We study QCD radiation in decay processes involving heavy particles. As input, the first-order gluon emission rate is calculated in a number of reactions, and comparisons of the energy flow patterns show a non-negligible process dependence. To proceed further, the QCD parton shower language offers a convenient approach to include multi-gluon emission effects, and to describe exclusive event properties. An existing shower algorithm is extended to take into account the process-dependent mass, spin and parity effects, as given by the matrix element calculations. This allows an improved description of multiple gluon emission effects off b and t quarks, and also off nonstandard particles like squarks and gluinos. Phenomenological applications are presented for bottom production at LEP, Higgs particle decay to heavy flavours, top production and decay at linear colliders, and some simple supersymmetric processes.
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| 6. |
- Norrbin, E., et al.
(författare)
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Transverse momentum as a measure of color topologies
- 1997
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Ingår i: Physical review D: Particles and fields. - 1550-2368. ; 55:1, s. 5-9
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Tidskriftsartikel (refereegranskat)abstract
- Several distinct color 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 [Formula presented] and four-jet [Formula presented] 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 color rearrangement effects.
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