| 1. |
- Andersen, JR, et al.
(author)
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Small-x phenomenology - summary and status 2002
- 2004
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In: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 35:1, s. 67-98
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Research review (peer-reviewed)abstract
- A second workshop on small-x physics, within the Small-x Collaboration, was held in Lund in June 2002 with the aim of over-viewing recent theoretical progress in this area and summarizing the experimental status.
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| 2. |
- Andersson, Bo, et al.
(author)
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Small x phenomenology: summary and status
- 2002
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In: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 25:1, s. 77-101
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Research review (peer-reviewed)abstract
- The aim of this paper is to summarize the general status of our understanding of small-x physics. It is based on presentations and discussions at an informal meeting OIL this topic held in Lund, Sweden, in March 2001. This document also marks the founding of an informal collaboration between experimentalists and theoreticians with a special interest in small-x physics. This paper is dedicated to the memory of Bo Andersson. who died unexpectedly from a heart attack on March 4th, 2002.
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| 3. |
- Gustafson, Gösta, et al.
(author)
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A simple model for the BFKL-DGLAP transition in deep inelastic scattering
- 2002
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In: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 23:2, s. 267-274
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Journal article (peer-reviewed)abstract
- A simple model is presented which interpolates between the DGLAP and BFKL regimes in deep inelastic cp scattering. This model is based on the CCFM and LDC models, and it is simple enough to provide an intuitive picture of the transition region between the two domains. Results are presented for both fixed and running coupling; for fixed coupling the transition between the domains occurs at a constant ratio between Ink 2 L and In 1/x, while for a running coupling it occurs for constant ratio between lnlnk(2) and ln 1/x.
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| 4. |
- Gustafson, Gösta, et al.
(author)
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Gluon distribution functions in the k(perpendicular to) -factorization approach
- 2002
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 33:10, s. 2989-2993
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Journal article (peer-reviewed)abstract
- At small x, the effects of finite transverse momenta of partons inside a hadron become increasingly important, especially in analyses of jets and heavy-quark production. These effects can be systematically accounted for in a formalism based on k(perpendicular to)-factorization and unintegrated distribution functions. We present results for the unintegrated distribution function, together with the corresponding integrated one, obtained within the framework of the Linked Dipole Chain model. Comparisons are made to results obtained within other approaches.
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| 5. |
- Gustafson, Gösta, et al.
(author)
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Hadronic collisions in the linked dipole chain model
- 2003
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 67:034020:3
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Journal article (peer-reviewed)abstract
- We apply the Linked Dipole Chain model to hadronic collisions using a modified version of the LDCMC Monte Carlo program. In particular we investigate the effects of multiple scatterings, which in this framework are reformulated in terms of the production of multiple chains of dipoles. We find, among other things, that this way of describing multiple scatterings is less sensitive to the treatment of soft, non-perturbative, scatterings. Although the results presented here are only at parton level, by comparing with corresponding results from PYTHIA, we are confident that our model will be able to describe essential features of high energy hadronic collisions, including underlying events and jet-pedestal effects in high pT events. The model should also be applicable to estimates of transverse energy flow in high energy heavy ion collisions, of interest in analyses of signals for quark-gluon plasma formation.
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| 6. |
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| 7. |
- Miu, Gabriela
(author)
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Analyses of Electron-Proton and Hadron-Hadron Collisions Using the Linked Dipole Chain Model
- 2002
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Doctoral thesis (other academic/artistic)abstract
- In this thesis we perform phenomenological studies of Quantum Chromodynamics, as manifested in deeply inelastic electron-proton (DIS) and high-energy hadron-hadron interactions. Most of the results are obtained using the Linked Dipole Chain model (LDC). This model was originally developed for studies of DIS and is formulated in terms of kT-factorization and un-integrated parton distribution functions. We develop a simple model, based on the CCFM and LDC models, which interpolates between the DGLAP and BFKL regimes in DIS. This model gives an intuitive qualitative picture of the transition region between the DGLAP and BFKL domains. We use an approximate version of the LDC model to obtain qualitative results for the inclusive minijet cross section and transverse energy flow, expected to be relevant in analyses of future high-energy hadron-hadron or nucleus-nucleus collisions. Our results contain a dynamical suppression at small transverse momenta, which corresponds to an effective cutoff which is slowly increasing with the total collision energy. This is in contrast to the traditional approach based on collinear factorization, which results in an inclusive cross section that diverges at small transverse momenta and implies the introduction of a cutoff parameter whose value needs to be adjusted to data. The LDC model is particularly suitable for a description of e.g. the cross section for jets and heavy quarks at very high energies, where the effects of finite transverse momenta of partons inside the hadrons become increasingly important. We obtain results for the LDC integrated and un-integrated gluon distribution functions and compare them with those of other formalisms, e.g. those based on the CCFM model, demonstrating how to make a relevant comparison between the different formalisms. We exploit the symmetric formulation of the LDC model with respect to the photon and proton ends and develop a version of the LDC model for hadronic interactions. In this preliminary analysis, we focus on features of jet and minijet production which are less sensitive to hadronization effects and compare our results to those of the PYTHIA event generator.
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| 8. |
- Miu, Gabriela, et al.
(author)
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W production in an improved parton-shower approach
- 1999
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 449:3-4, s. 313-320
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Journal article (peer-reviewed)abstract
- In the description of the production properties of gauge bosons (W±, Z0, γ*) at colliders, the lowest-order graph normally is not sufficient. The contributions of higher orders can be introduced either by an explicit order-by-order matrix-element calculation, by a resummation procedure or by a parton-shower algorithm. Each approach has its advantages and disadvantages. We here introduce a method that allows the parton-shower algorithm to be augmented by higher-order information, thereby offering an economical route to a description of all event properties. It is tested by comparing with the P⊥ spectrum of W bosons at the Tevatron.
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| 9. |
- Sjöstrand, Torbjörn, et al.
(author)
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High-energy-physics event generation with PYTHIA 6.1
- 2001
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In: Computer Physics Communications. - 0010-4655. ; 135:2, s. 238-259
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Journal article (peer-reviewed)abstract
- Pythia version 6 represents a merger of the Pythia 5, Jetset 7 and SPythia programs, with many improvements. It can be used to generate high-energy-physics 'events', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions. The underlying physics is not understood well enough to give an exact description; the programs therefore contain a combination of analytical results and various models. The emphasis in this article is on new aspects, but a few words of general introduction are included. Further documentation is available on the web.
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