| 1. |
- Andersson, Bo, et al.
(författare)
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The Feynman-Wilson gas and the Lund model
- 1999
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 7:2, s. 251-261
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Tidskriftsartikel (refereegranskat)abstract
- We derive a partition function for the Lund fragmentation model and compare it with that of a classical gas. For a fixed rapidity “volume” this partition function corresponds to a multiplicity distribution which is very close to a binomial distribution. We compare our results with the multiplicity distributions obtained from the JETSET Monte Carlo for several scenarios. Firstly, for the fragmentation vertices of the Lund string. Secondly, for the final state particles both with and without decays.
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| 2. |
- Angelopoulos, Angelos, et al.
(författare)
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Dispersion relation analysis of the neutral kaon regeneration amplitude in carbon
- 1999
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Ingår i: European Physical Journal C. - : Springer Berlin/Heidelberg. - 1434-6044 .- 1434-6052. ; 10:1, s. 19-25
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Tidskriftsartikel (refereegranskat)abstract
- We apply a forward dispersion relation to the regeneration amplitude for kaon scattering on 12" style="position: relative;" tabindex="0" id="MathJax-Element-1-Frame" class="MathJax">12C using all available data. The CPLEAR data at low energies allow the determination of the net contribution from the subthreshold region which turns out to be much smaller than earlier evaluations, solving a long standing puzzle.
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| 3. |
- Caso, C., et al.
(författare)
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Review of particle physics. Particle Data Group
- 1998
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; C3, s. 1-794
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Forskningsöversikt (refereegranskat)
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| 4. |
- Gustafson, Gösta, et al.
(författare)
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On particle multiplicities distribution in three-jet events
- 1999
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 11:2, s. 345-350
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Tidskriftsartikel (refereegranskat)abstract
- A thorough verification of the distinct differences in the properties of quark and gluon jets is considered as one of the most instructive tests of the basic ideas of QCD. In the real life experiments such a comparison appears to be quite a delicate task and various subtle issues require further theoretical efforts. In this paper we discuss in detail the possibility to extract the theoretically adequate information from the particle multiplicity patterns in three-jet events in e+e− annihilation.
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| 5. |
- Gustafson, Gösta, et al.
(författare)
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Using two jet events to understand hadronization
- 1999
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 8:3, s. 435-445
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Tidskriftsartikel (refereegranskat)abstract
- While the hard phase of the strong interaction is well described by perturbative QCD, the soft hadronization phase is less understood. Benefiting from the high statistics from e+e− experiments at the Z0 resonance, it is possible to impose strong two-jet cuts on the data without losing the statistical significance. In these events perturbative activity is suppressed and hadronization effects can be more prominent. We show that after proper event cuts a set of observables are sensitive to differences in the hadronization models. These observables can thus be important tools for a more detailed study of the hadronization mechanism.
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| 6. |
- Häkkinen, Jari, et al.
(författare)
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Bose-Einstein and colour interference in W-pair decays
- 1998
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 5:2, s. 275-281
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Tidskriftsartikel (refereegranskat)abstract
- We study effects on the W mass measurements at LEP2 from non-perturbative interference effects in the fully hadronic decay channel. Based on a model for Bose-Einstein interference, which is in agreement with LEP1 data, we argue that there are no Bose-Einstein correlations between bosons coming from the different W's. For small reconnection probabilities we rule out the possible experimental signal of colour interference at LEP2, suggested in [1]. The conclusions from this paper are that the theoretical uncertainties in the W mass determination should be smaller than the experimental statistical error.
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| 7. |
- Khoze, V. A., et al.
(författare)
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Soft-particle spectra as a probe of interconnection effects in hadronic W+W- events
- 1999
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 6:2, s. 271-284
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Tidskriftsartikel (refereegranskat)abstract
- Cross-talk between the W+ and W- sources of hadron production at LEP2 offers a hope to learn about basic properties of QCD, but at the same time threatens high-precision measurements of the W boson mass. Directly visible effects are not expected to be large, however. It is, therefore, important to develop methods to measure the level of interconnection in the data - 'connectometers'. In this article we study one particular set of observables, namely the reduced rate of low-momentum particle production caused by reconnection. In realistic scenarios the expected signals are at the border of visibility, but not quite beyond reach. Special studies on kaons and protons, or with other subsets of the data, could provide supporting evidence. We also show how LEP1 Z0 events could be used to define an alternative reference sample.
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| 8. |
- Lönnblad, Leif, et al.
(författare)
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Modeling Bose-Einstein correlations at LEP-2
- 1998
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 2:1, s. 165-180
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Ohlsson, Tommy, 1973-, et al.
(författare)
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Chiral quark model analysis of nucleon quark sea isospin asymmetry and spin polarization
- 1999
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Ingår i: European Physical Journal C. - : Springer-Verlag. - 1434-6044 .- 1434-6052. ; 7:3, s. 501-506
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Tidskriftsartikel (refereegranskat)abstract
- We analyze recent measurements of the nucleon quark sea isospin asymmetry in terms of the chiral quark model. The new measurements indicate that the SU(3) model with modest symmetry breaking and no eta' Goldstone boson gives a satisfactory description of data. We also discuss the matching parameter for the axial-vector current. Finally, we analyze the nucleon quark spin polarization measurements directly in the chiral quark model without using any SU(3) symmetry assumption on the hyperon axial-vector form factors. The new data indicate that the chiral quark model gives a remarkably good and consistent description of all low energy baryon measurements.
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| 10. |
- Ohlsson, Tommy, 1973-, et al.
(författare)
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Weak form factors for semileptonic octet baryon decays in the chiral quark model
- 1999
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Ingår i: European Physical Journal C. - : Springer-Verlag. - 1434-6044 .- 1434-6052. ; 6:2, s. 285-296
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Tidskriftsartikel (refereegranskat)abstract
- We study the weak vector and axial-vector form factors of first- and second-class currents for the semileptonic octet baryon decays in the spirit of the chiral quark model. Our results for the weak magnetism form factors are consistent with the conserved vector current (CVC) results. The induced pseudotensor form factors, which are highly model dependent. are small. The overall performance of the chiral quark model is quite good and in general agreement with existing experimental data.
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