| 1. |
- Albacete, Javier L., et al.
(författare)
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Predictions for p + Pb Collisions at sN N = √5 TeV : Comparison with Data
- 2016
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Ingår i: International Journal of Modern Physics E. - 0218-3013. ; 25:9
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Forskningsöversikt (refereegranskat)abstract
- Predictions made in Albacete et al. [Int. J. Mod. Phys. E 22 (2013) 1330007] prior to the LHC p+Pb run at sNN = 5 TeV are compared to currently available data. Some predictions shown here have been updated by including the same experimental cuts as the data. Some additional predictions are also presented, especially for quarkonia, that were provided to the experiments before the data were made public but were too late for the original publication.
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| 2. |
- Helenius, Ilkka, et al.
(författare)
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Electron-ion physics with the LHeC
- 2015
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Ingår i: Proceedings of Science. - 1824-8039.
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Tidskriftsartikel (refereegranskat)abstract
- The Large Hadron Electron Collider (LHeC) project is the proposal to use the existing LHC proton/ion beams and construct a new electron beam line to perform high-energy electron-proton/ion collisions. In this talk, we consider some of the physics topics that could be studied in the electronion mode. In particular, we estimate how much the current nuclear parton distribution fits could be improved with the deeply inelastic scattering measurements at the LHeC by including pseudodata into a global analysis. In addition, we discuss briefly other topics that would help to better understand some aspects of heavy-ion collisions, namely small-x physics and hadron production with a nuclear target.
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| 3. |
- Helenius, Ilkka, et al.
(författare)
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Neutron-skin effect and centrality dependence of high-pT observables in nuclear collisions
- 2016
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Ingår i: Proceedings of Science. - 1824-8039. ; 11-15-April-2016
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Tidskriftsartikel (refereegranskat)abstract
- We report on our studies of the neutron-skin effects in high-pT observables at the LHC. We study the impact of the neutron-skin effect on the centrality dependence of inclusive direct photon, highpT hadron and W± production in nuclear collisions at the LHC. The neutron-skin effect refers to the observation that in spherical heavy nuclei, the tail of the neutron distribution extends farther than the distribution of protons, which can affect observables sensitive to electroweak phenomena in very peripheral collisions. We quantify this effect for direct photons, charged hadrons and W bosons as a function of the collision centrality. In the case of direct photons we find that it will be difficult to resolve the neutron-skin effect, given the uncertainties in the nuclear PDFs and their spatial dependence. With charged hadrons and W's, however, up to 20 % unambiguous effects are expected for most peripheral collisions.
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| 4. |
- Helenius, Ilkka, et al.
(författare)
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Neutron-skin effect in direct-photon and charged-hadron production in Pb+Pb collisions at the LHC
- 2017
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:3
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Tidskriftsartikel (refereegranskat)abstract
- A well-established observation in nuclear physics is that in neutron-rich spherical nuclei the distribution of neutrons extends farther than the distribution of protons. In this work, we scrutinize the influence of this so called neutron-skin effect on the centrality dependence of high-pT direct-photon and charged-hadron production. We find that due to the estimated spatial dependence of the nuclear parton distribution functions, it will be demanding to unambiguously expose the neutron-skin effect with direct photons. However, when taking a ratio between the cross sections for negatively and positively charged high-pT hadrons, even centrality-dependent nuclear-PDF effects cancel, making this observable a better handle on the neutron skin. Up to 10% effects can be expected for the most peripheral collisions in the measurable region.
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| 5. |
- Helenius, Ilkka, et al.
(författare)
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NPDF constraints from the Large Hadron Electron Collider
- 2016
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Ingår i: Proceedings of Science. - 1824-8039. ; 11-15-April-2016
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Tidskriftsartikel (refereegranskat)abstract
- An updated analysis regarding the expected nuclear PDF constraints from the future Large Hadron Electron Collider (LHeC) experiment is presented. The new study is based on a more flexible small-x parametrization which provides less biased uncertainty estimates in the region where there are currently no data constraints. The effect of the LHeC is quantified by directly including a sample of pseudodata according to the expected precision of this planned experiment. As a result, a significant reduction of the small-x uncertainties in sea quarks and gluons is observed.
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| 6. |
- Helenius, Ilkka, et al.
(författare)
-
Nuclear PDF constraints from p+Pb collisions at the LHC
- 2015
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Ingår i: Proceedings of Science. - 1824-8039.
-
Tidskriftsartikel (refereegranskat)abstract
- As the current nuclear PDF analyses are mainly constrained by fixed-target Drell-Yan and deeply inelastic scattering data only the quark nuclear modifications at fairly large x values are in a good control. Inclusive pion production in d+Au collisions at RHIC provides some constraints for gluons but due to the limited kinematic reach of the data the gluon modifications remain uncertain especially at small values of x. In this talk, we discuss how the existing data from p+Pb collisions at the LHC can improve the nuclear PDF fits and which measurements would be sensitive to the small-x gluons. In particular, we consider inclusive hadron production, compare this to direct photons, and show estimates of the effect of CMS dijet measurements to the uncertainty of nuclear gluon distributions.
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