446 research outputs found
LHC data challenges the contemporary parton-to-hadron fragmentation functions
We discuss the inclusive high-pT charged-particle production in proton-proton
collisions at the LHC. The experimental data are compared to the NLO
perturbative QCD calculations employing various sets of parton-to-hadron
fragmentation functions. Most of the theoretical predictions are found to
disastrously overpredict the measured cross sections, even if the scale
variations and PDF errors are accounted for. The problem appears to arise from
the presently too hard gluon-to-hadron fragmentation functions.Comment: Transcription of the talk given in DIS2014 conferenc
Modeling the Impact Parameter Dependence of the nPDFs With EKS98 and EPS09 Global Fits
So far the nuclear PDFs (nPDFs) in the global DGLAP fits have been taken to
be spatially independent. In this work, using the -dependence of the
globally fitted sets EPS09 and EKS98, we have determined the spatial dependence
of the nPDFs in terms of powers of the nuclear thickness functions. New
spatially dependent nPDF sets EPS09s (NLO, LO, error sets) and EKS98s (LO) are
released. As an application, we consider the nuclear modification factor
at midrapidity for neutral pion production in deuteron-gold
collisions at RHIC in NLO. Comparison with the PHENIX data in different
centrality classes is also shown. In addition, predictions for the
corresponding nuclear modification factor in proton-lead
collisions at the LHC are discussed.Comment: 4 pages, 4 figures, Talk given at Hard Probes 2012, 27 May - 1 June,
2012, Cagliari (Sardinia, Italy). V2: Added one commen
EPS09s and EKS98s: Impact parameter dependent nPDF sets
In our recent study we have determined two new spatially dependent nuclear
PDF (nPDF) sets, EPS09s and EKS98s. With these, the hard-process cross-sections
can be calculated in different centrality classes consistently with the
globally analyzed nPDFs for the first time. The sets were determined by
exploiting the -systematics of the globally fitted nPDF sets, EPS09 and
EKS98. For the spatial dependence of the nPDFs we used a power series ansatz in
the nuclear thickness function . In this flash talk we introduce the
framework, and present our NLO EPS09s-based predictions for the nuclear
modification factor in four centrality classes for inclusive neutral pion
production in p+Pb collisions at the LHC and for inclusive prompt photon
production in d+Au collisions at RHIC at midrapidity.Comment: 4 pages, 4 figures, Contribution to the proceedings of the Quark
Matter 2012, Washington D.C., August 12-18, 201
EXPLAINING AN E-IDENTIFICATION FRAMEWORK IMPLEMENTATION USING DIALECTICS
This article analyses the challenges of implementing a new electronic identification (eID) framework in Finland. We employ the theoretical lens of dialectics to explain how two opposing forces in the form of public and private actors, the government and banks respectively, engaged in a process of resistance and acquiescence. By interviewing the key organizations from both sides, we identify the rationale of the conflict, mechanisms that have led and may lead to further conflict, and the outcome. The root cause of the problems with the framework include the conflicting goals of the government and banks: the regulators’ interests to create more competition in the market, generate cost savings, decrease the dependence on banks vs. the objectives of the banks to maintain the status quo. Moreover, the framework implementation practices, such as the hard enforcement strategy, an inherent infrastructuring mindset of the government and communication problems, have considerably contributed to further conflict development. As a result, divergent views on the framework architecture and the pricing models are the outcomes of the confrontation. Our findings emphasize the importance of strategic and operational coherence in the governance of a changing ecosystem with a proprietary banking platform playing a role in a national eID scheme
Probing the small-x nuclear gluon distributions with isolated photons at forward rapidities in p plus Pb collisions at the LHC
Peer reviewe
Neutron-skin effect in direct-photon and charged-hadron production in Pb plus Pb collisions at the LHC
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-p(T) 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-p(T) 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.Peer reviewe
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