Search results for "distribution function"
showing 10 items of 348 documents
Electron Ion Collider: The Next QCD Frontier: Understanding the glue that binds us all
2016
International audience; This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics over the past decades and, in particular, the focus…
Integrating Cross-Dominance Adaptation in Multi-objective Memetic Algorithms
2008
This chapter proposes a novel adaptive memetic approach for solving multi-objective optimization problems. The proposed approach introduces the novel concept of crossdominance and employs this concept within a novel probabilistic scheme which makes use of the Wigner distribution for performing coordination of the local search. Thus, two local searchers are integrated within an evolutionary framework which resorts to an evolutionary algorithm previously proposed in literature for solving multi-objective problems. These two local searchers are a multi-objective version of simulated annealing and a novel multi-objective implementation of the Rosenbrock algorithm.
The Impact of Bank Concentration on Financial Distress: The Case of the European Banking System
2009
This paper examines the impact of bank concentrationon bank financial distress using a balanced panel of commercial banks in the EU‐25 over a sample period running from 2003 to 2007. Financial distress is proxied by the observations falling below a given threshold of the empirical distribution of a risk‐adjusted indicator of bank performance: the Shareholder Value Ratio. We employ a panel probit regression estimated by GMM in order to obtain consistent and efficient estimates, following the suggestion made by Bertschek and Lechner (1998). After controlling for a number of environment variables, we conclude that our findings suggest a positive effect of bank concentration on financial distre…
Constraints on nuclear parton distributions from dijet photoproduction at the LHC
2019
Using QCD calculations of the cross section of inclusive dijet photoproduction in Pb-Pb ultraperipheral collisions in the LHC kinematics as pseudo-data, we study the effect of including these data using the Bayesian reweighting technique on nCTEQ15, nCTEQ15np, and EPPS16 nuclear parton distribution functions (nPDFs). We find that, depending on the assumed error of the pseudo-data, it leads to a significant reduction of the nPDF uncertainties at small values of the momentum fraction $x_A$. Taking the error to be 5\%, the uncertainty of nCTEQ15 and nCTEQ15np nPDFs reduces approximately by a factor of two at $x_A=10^{-3}$. At the same time, the reweighting effect on EPPS16 nPDFs is much smalle…
Préparation et spéciation d’oxo-clusters de métaux du bloc p
2022
The main subject of this thesis is the use of Pair Distribution Function (PDF) analysis for solution phase speciation during metal-cluster growth. The PDF method allows the extraction of structural information from a sample in the form of an atom-atom distance distribution via Fourier transform of synchrotron X-ray scattering data. The growth mechanisms of two solution-based systems are analysed in this thesis. Precursor materials are synthesized through a mechanochemical method that was developed and shown to be able to access a wide range of related systems.Mechanochemical routes of synthesizing bismuth Active Pharmaceutical Ingredients (APIs) were investigated and optimised. Samples were…
Nuclear structure functions at a future electron-ion collider
2017
The quantitative knowledge of heavy nuclei's partonic structure is currently limited to rather large values of momentum fraction $x$---robust experimental constraints below $x\ensuremath{\sim}{10}^{\ensuremath{-}2}$ at low resolution scale ${Q}^{2}$ are particularly scarce. This is in sharp contrast to the free proton's structure which has been probed in Deep Inelastic Scattering (DIS) measurements down to $x\ensuremath{\sim}{10}^{\ensuremath{-}5}$ at perturbative resolution scales. The construction of an electron-ion collider (EIC) with a possibility to operate with a wide variety of nuclei, will allow one to explore the low-$x$ region in much greater detail. In the present paper we simula…
Nuclear PDFs from the LHeC perspective
2013
We study the prospects for constraining the nuclear parton distribution functions by small-x deep inelastic scattering. Performing a global fit of nuclear parton distribution functions including a sample of pseudodata representing expected measurements at the planned LHeC collider, we demonstrate that the accuracy of the present nuclear parton distributions could be be improved substantially. We also discuss the impact of flavour-tagged data.
New Results on Charm Production at HERA
2014
The copious production of charm quarks at HERA yielded measure- ments of the charm contribution to the proton structure and of the charm mass and fragmentation parameters of charmed hadrons. Several measure- ments of charm production in deep inelastic scattering from the H1 and ZEUS collaborations as well as combined data are presented. They provide a powerful vindication of the form of the gluon density in the proton de- rived from scaling violations of inclusive deep inelastic scattering data. A QCD fit to the charm data leads to a measurement of the charm mass and provides precise predictions e.g. for W and Z production at the LHC. In ad- dition, charm fragmentation fractions in photopro…
An analysis of the impact of LHC Run I proton–lead data on nuclear parton densities
2016
We report on an analysis of the impact of available experimental data on hard processes in proton-lead collisions during Run I at the Large Hadron Collider on nuclear modifications of parton distribution functions. Our analysis is restricted to the EPS09 and DSSZ global fits. The measurements that we consider comprise production of massive gauge bosons, jets, charged hadrons and pions. This is the first time a study of nuclear PDFs includes this number of different observables. The goal of the paper is twofold: i) checking the description of the data by nPDFs, as well as the relevance of these nuclear effects, in a quantitative manner; ii) testing the constraining power of these data in eve…
Double parton scattering: A study of the effective cross section within a Light-Front quark model
2015
We present a calculation of the effective cross section $\sigma_{eff}$, an important ingredient in the description of double parton scattering in proton-proton collisions. Our theoretical approach makes use of a Light-Front quark model as framework to calculate the double parton distribution functions at low-resolution scale. QCD evolution is implemented to reach the experimental scale. The obtained $\sigma_{eff}$, when averaged over the longitudinal momentum fractions of the interacting partons, $x_i$, is consistent with the present experimental scenario. However the result of the complete calculation shows a dependence of $\sigma_{eff}$ on $x_i$, a feature not easily seen in the available…