| 1. |
- Andersson, Bo, et al.
(författare)
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Is there screwiness at the end of the QCD cascades?
- 1998
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :9
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Tidskriftsartikel (refereegranskat)abstract
- We discuss what happens at the end of the QCD cascades. We show that, with just a few reasonable assumptions, the emission of soft gluons is constrained to produce an ordered field in the form of a helix. We describe how to modify the Lund fragmentation scheme in order to fragment such a field. Our modified fragmentation scheme yields results which are consistent with current experimental measurements, but predicts at least one signature which should be observable.
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| 2. |
- Bijnens, Johan, et al.
(författare)
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Matching the heavy vector meson theory
- 1998
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 1998:JHEP01(1998)
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Tidskriftsartikel (refereegranskat)abstract
- We show how to obtain a "heavy" meson effective lagrangian for the case where the number of heavy particles is not conserved. We apply the method in a simple example at tree level and perform then the reduction for the case of vector mesons in Chiral Perturbation Theory in a manifestly chiral invariant fashion. Some examples showing that "heavy" meson effective theory also reproduces the correct non-analytical terms at the one-loop level are included.
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| 3. |
- Bijnens, Johan, et al.
(författare)
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The ΔI = 1/2 rule in the chiral limit
- 1999
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 1999:JHEP01(1999)
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the matching between long-distance and short-distance at next-to-leading in 1/Nc and show how the scheme-dependence from the two-loop renormalization group running can be treated. We then use this method to study the three O(p2) terms contributing to non-leptonic kaon decays, namely the usual octet and 27-plet derivative terms as well as the weak mass term using the Extended Nambu Jona-Lasinio model as the low energy approximation. We also discuss subtleties in the momentum routing in the low energy theory and a problem in separating factorizable and non-factorizable contributions from the Q6 operator in the chiral limit. We update our earlier results on the BK parameter as well.
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| 4. |
- Gustafson, Gösta, et al.
(författare)
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Energy and virtuality scale dependence in quark and gluon jets
- 1998
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 1998:JHEP09(1998)
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Tidskriftsartikel (refereegranskat)abstract
- We discuss some important issues concerning multiplicities in quark and gluon jets in e+e- annihilation. In QCD the properties of a jet in general depend on two scales, the energy and virtuality of the jet. Frequently theoretical predictions apply to a situation where these scales coincide, while for experimental data they are often different. Thus an analysis to extract e.g. the asymptotic multiplicity ratio CF/CA between quark and gluon jets, needs a carefully specified jet definition, together with a calculation of nonleading corrections to the multiplicity evolution. We propose methods to systematically study the separate dependence upon the two scales in experimental data and compare the results with theory. We present jet finding algorithms which corresponds well to the theoretically considered jets. We also show that recoil effects add corrections to the modified leading log approximation which are quantitatively important, though formally suppressed at high energies.
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| 5. |
- Kharraziha, Hamid, et al.
(författare)
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The linked dipole chain Monte Carlo
- 1998
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- We present an implementation of the Linked Dipole Chain model for deeply inelastic ep scattering into the framework of the ARIADNE event generator. Using this implementation we obtain results both for the inclusive structure function as well as for exclusive properties of the hadronic final state.
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| 6. |
- Moretti, Stefano, et al.
(författare)
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New and old jet clustering algorithms for electron-positron events
- 1998
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 1998:JHEP08(1998)
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Tidskriftsartikel (refereegranskat)abstract
- Over the years, many jet clustering algorithms have been proposed for the analysis of hadronic final states in e+e- annihilations. These have somewhat different emphasis and are therefore more or less suited for various applications. We here review some of the most used and compare them from a theoretical and experimental point of view.
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