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 $A$-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 $R_{dAu}^{\pi^0}$ 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 $R_{pPb}^{\pi^0}$ 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 $A$-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 $T_A$. 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

Standard and magnetically controlled growing rods for the treatment of early onset scoliosis

Distraction based spinal instrumentation represents the most common and standard surgical technique to correct early onset scoliosis (EOS), i.e., scoliosis which has been diagnosed before the age of 10 years. Surgical treatment of EOS aims at controlling spinal deformity while maintaining spinal growth which is mandatory for the development of normal lung capacity. To achieve these goals the spinal instrumentation needs to be distracted to facilitate spinal growth during treatment. Distraction can be obtained by repeated surgical lengthenings (traditional growing rods, TGRs) or using magnetically controlled growing rods (MCGRs), which can be lengthened using external remote controller on an outpatient basis. The outcomes of TGR instrumentation for EOS are well described with follow-up until skeletal maturity: normal spinal growth can be maintained, 40-50% of the scoliosis can be corrected, but there is an over 50% risk of complications including deep wound infection, rod failure, and instrumentation pull-out. MCGR instrumentation may reduce the risk of wound related complications, provides similar deformity correction, but may not provide as much spinal growth. Metallosis around the instrumentation necessitates MCGR removal and definitive final instrumented fusion at the end of growth friendly management. Even severe EOS can be treated using distraction based spinal instrumentation

Probing the small-x nuclear gluon distributions with isolated photons at forward rapidities in p plus Pb collisions at the LHC

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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