| 11. |
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| 12. |
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| 13. |
- Armesto, N., et al.
(författare)
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Heavy-ion collisions at the LHC-Last call for predictions
- 2008
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 35:5, s. 054001-
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Forskningsöversikt (refereegranskat)abstract
- This writeup is a compilation of the predictions for the forthcoming Heavy Ion Program at the Large Hadron Collider, as presented at the CERN Theory Institute 'Heavy Ion Collisions at the LHC - Last Call for Predictions', held from 14th May to 10th June 2007.
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| 14. |
- B, Mariotto Cristiano, et al.
(författare)
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Hard and soft QCD in charmonium production
- 2000
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We show that both hard perturbative and soft non-perturbative QCD effects are important in hadroproduction of charmonium. Observed $x_F$ and $p_\perp$ distributions of J/psi in fixed target experiments can be well described by our Monte Carlo model based
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| 15. |
- Barlow, R., et al.
(författare)
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Report of the heavy flavors working group
- 1991
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 17:10, s. 1605-1623
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- After a brief discussion of the statistics available to the four LEP experiments at the time of writing and an overview of B-event characteristics, the authors consider in particular the theory, practice and potential pitfalls of neural networks, a new approach to B tagging which attracted a great deal of interest. They then consider some of the QCD aspects of heavy flavour physics. Finally there is a brief discussion of the prospects for heavy flavour physics at HERA.
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| 16. |
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| 17. |
- Danielsson, Ulf, et al.
(författare)
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Heavy photophilic scalar at the LHC from a varying electromagnetic coupling
- 2017
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Ingår i: Nuclear Physics B. - : Elsevier BV. - 0550-3213 .- 1873-1562. ; 919, s. 569-582
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the phenomenology of a heavy scalar ϕ of the type involved in Bekenstein's framework for varying electromagnetic coupling theories, with the difference that the scalar in our model has a large mass. The model has only two free parameters, the mass Mϕ of the scalar and the scale Λ of new physics. The scalar is dominantly produced through photon-photon fusion at the LHC and leads to a diphoton final state. It can also be produced by quark-antiquark fusion in association with a photon or a fermion pair. Its dominating decay is to diphotons, but it also has a large three-body branching to a fermion pair and a photon, which can provide an interesting search channel with a dilepton-photon resonance. We derive exclusion limits on the Mϕ−Λplane from the latest 13 TeV LHC diphoton resonance search data. For a benchmark mass of Mϕ∼1 TeV, we find a lower limit on Λ of 18 TeV. We discuss the more complex possibility of varying couplings in the full electroweak theory and comment on the possibility that the new physics is related to extra dimensions or string theory.
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| 18. |
- Danielsson, Ulf, et al.
(författare)
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Varying gauge couplings and collider phenomenology
- 2019
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Ingår i: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 100:5
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we investigate a natural extension of the Standard Model that involves varying coupling constants. This is a general expectation in any fundamental theory such as string theory, and there are good reasons for why new physics could appear at reachable energy scales. We investigate the collider phenomenology of models with varying gauge couplings where the variations are associated with real singlet scalar fields. We introduce three different heavy scalar fields that are responsible for the variations of the three gauge couplings of the Standard Model. This gives rise to many interesting collider signatures that we explore, resulting in exclusion limits based on the most recent LHC data, and predictions of the future discovery potential at the high-luminosity LHC.
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| 19. |
- Dittmar, M, et al.
(författare)
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Parton distributions: Summary report for the HERA - LHC workshop
- 2005
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Konferensbidrag (populärvet., debatt m.m.)abstract
- We provide an assessment of the impact of parton distributions on the determination of LHC processes, and of the accuracy with which parton distributions (PDFs) can be extracted from data, in particular from current and forthcoming HERA experiments. We give an overview of reference LHC processes and their associated PDF uncertainties, and study in detail W and Z production at the LHC. We discuss the precision which may be obtained from the analysis of existing HERA data, tests of consistency of HERA data from different experiments, and the combination of these data. We determine further improvements on PDFs which may be obtained from future HERA data (including measurements of $F_L$), and from combining present and future HERA data with present and future hadron collider data. We review the current status of knowledge of higher (NNLO) QCD corrections to perturbative evolution and deep-inelastic scattering, and provide reference results for their impact on parton evolution, and we briefly examine non-perturbative models for parton distributions. We discuss the state-of-the art in global parton fits, we assess the impact on them of various kinds of data and of theoretical corrections, by providing benchmarks of Alekhin and MRST parton distributions and a CTEQ analysis of parton fit stability, and we briefly presents proposals for alternative approaches to parton fitting. We summarize the status of large and small x resummation, by providing estimates of the impact of large x resummation on parton fits, and a comparison of different approaches to small x resummation, for which we also discuss numerical techniques.
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| 20. |
- Dombey, S., et al.
(författare)
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QCD evolution of jets in the quark-gluon plasma
- 2008
-
Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 808, s. 178-191
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Tidskriftsartikel (refereegranskat)abstract
- The quark-gluon plasma (QGP) can be explored in relativistic heavy ion collisions by the jet quenching signature, i.e. by the energy loss of a high energy quark or gluon traversing the plasma. We introduce a novel QCD evolution formalism in the leading logarithm approximation, where normal parton radiation is interleaved with scattering on the plasma gluons occuring at a similar time scale. The idea is elaborated in two approaches. One extends the DGLAP evolution equations for fragmentation functions to include scatterings in the medium, which facilitates numerical solutions for comparison with data and provides a basis for a Monte Carlo implementation. The other approach is more general by including also the transverse momentum dependence of the jet evolution, which allows a separation of the scales also for the scattering term and provides a basis for analytical investigations. The two approaches are shown to be related and give the same characteristic softening of the jet depending on the temperature of the plasma. A substantial effect is found at the RHIC energy and is further enhanced at LHC. Systematic studies of data on the energy loss could, therefore, demonstrate the existence of the QGP and probe its properties.
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