Godat, eric, the impact of ppb wz lhc data on ncteq15 parton distribution functions with an emphasis on refitting the ncteq15 npdf set 2018. This page provides numerical table files for the computation of ct18 nexttoleading order nlo and nexttonexttoleading order nnlo parton distribution functions. Parton distribution functions definition scholarpedia. A parton distribution function pdf within so called collinear factorization is defined as the probability density. We compare the nuclear corrections factors from neutrino deepinelastic scattering dis with the ones coming from a standard analysis of nuclear parton distribution functions npdf. Because of the importance of pdfs, many groups perform and update global analyses of pdfs for protons 1, 2, 3 and for nuclei 4, 5, 6. Npdf stands for nuclear parton distribution function. Opensource qcd analysis of nuclear parton distribution. The parton distribution functions pdfs parametrizes the structure target as seen by the virtual photon and which are not computable from rst principles through perturbative calculations. The production of z bosons in ppb collisions at snn5.
The nuclear parton distribution functions npdf differ in magnitude from the pdf of the free proton. Nuclei are loosely bound systems with binding energy e b. Here, we discuss a compatibility of neutrino dis data with the nuclear correction factors obtained from npdf analysis focusing on the neutrino dis data from the nutev experiment. Here you can download a standalone fortran interface and demonstration program, as well as the tables with interpolated pdf values for the latest generalpurpose set cteq6. The critical component on the way to using the neutrino dis data in a proton pdf analysis is understanding the nuclear effects in parton distribution functions.
Theory experimental observables pdf parametrizations statistical aspects practical applications. Therefore we must sometimes use physics judgement in producing the pdf model, as an aid to the objec tive fitting procedures. Nuclear parton distribution function npdf 10 how do we extract the medium effect in pbpb collisions. Q where i labels the parton species depends on two variables. Eps09 a new generation of nlo and lo nuclear parton. Double parton scattering may constitute a signi cant background to important processes such as higgs boson production. National police defense foundation how is national police. Compatibility of global npdf analyses of neutrino dis and. Citeseerx eps09 global nlo analysis of nuclear pdfs and.
May 14, 2015 excel in tsql part 2 the normal distribution norm. Global analyses of nuclear parton distribution functions npdfs. Global perturbative qcd analyses, based on large data sets from ep and hadron collider experiments, provide tight constraints on the parton distribut. The dglapanalyses of the nuclear parton distribution functions npdf based on the global. Nlo global dglap analysis of nuclear parton distribution functions npdfs and their uncertainties. A code for carrying out the leadingorder evolution of such pdfs. This article explains the definition of parton densities also called parton distribution functions. We parametrize these effects by nuclear parton distribution functions npdf.
We present a first determination of the nuclear parton distribution functions npdf based on the nnpdf methodology. Pdf valence parton distribution function of pion from. Parton distribution functions pdfs are essential nonperturbative inputs for calculation of any observable with hadronic initial states. We report global analysis results of experimental data for nuclear structure function ratios fa2fa. Pdf uncertainties in higgs productions at lhc are significant. Nuclear parton distributions from leptonnucleus scattering. Protonlead collisions also provide an excellent opportunity to test npdf in a less dense. Description this package gives nuclear parton distribution functions npdfs of various nuclei starting from low q2 0. There is however not a unique set of parton distribution functions commonly accepted. The extension of these analyses to nuclear parton distribution functions npdfs has attracted much interest in recent years.
The cteq6 family of pdfs is superseded by newer, more complete, ct10 pdf sets. We present a nexttoleading order nlo global dglap analysis of nuclear parton distribution functions npdfs and their uncertainties. Nnpdf is defined as neural network parton distribution function somewhat frequently. As a result lacking precision and more free parameters the uncertainty of nuclear parton distribution functions is much larger than that for the free protons.
Dy in order to determine optimum parton distribution functions pdfs in nuclei. We perform a global chi2analysis of nuclear parton distribution functions using data from charged current neutrinonucleus deepinelastic scattering dis. Nnpdf stands for neural network parton distribution function. Citeseerx document details isaac councill, lee giles, pradeep teregowda.
A dis are not compatible with the predictions derived from. The impact of ppb wz lhc data on ncteq15 parton distribution. Heavy target data essential for determining separate parton flavors. Update and comparison of nuclear parton dis tribution. A parton distribution function pdf within so called collinear factorization is defined as the probability density for.
Introduction to parton distribution functions scholarpedia. Carrying out an nlo npdf analysis for the first time with three different types of experimental input deep inelastic. Parton distribution functions pdfs, which are universal characteristics of the target at high momentum transfer q2 driven by nonperturbative strong interactions. The curves were obtained using the pdfs from the herapdf analysis 14. Nuclear corrections of parton distribution functions arxiv. N2 in this contribution, we present a status report on the recent progress towards an analysis of nuclear parton distribution functions npdfs. We report global analysis results of experimental data for nuclear structurefunction ratios fa2fa.
Uncertainties of parton distribution functions slac. In order to use neutrino dis data in a global analysis of proton pdfs nuclear effects need to be understood. This paper examines certain features of double parton distribution functions, which are required to fully calculate the crosssections for double parton interactions. This analysis is based on neutralcurrent deepinelastic structure function data and is performed up to nnlo in qcd calculations with heavy quark mass effects. Nuclear pdf for neutrino and charged lepton data nasaads. Parton distribution functions and their applications.
Npdfs can help to understand the impact of high twist contributions on dis structure functions at low and moderate q2. Parton distribution functions can be abbreviated as pdf. Constrain npdf and test of the gluon saturation models. The extension of these analyses to nuclear parton distributions npdf has attracted much interest in recent years. Cteq collaborative effort to determine parton distribution functions inside of a free proton. The model uncertainties are related to the assumptions made in pdf. Npdf is listed in the worlds largest and most authoritative dictionary database of abbreviations and acronyms. Proton pdf are determined from data taken not only on protons but from some data. An introduction to the pdf determination by global analyses of the main pdf fitting groups with an emphasis on hera pdfs is presented. Nuclear parton distribution function how is nuclear. National police defense foundation how is national. In this talk, we present our recent nexttoleading order nlo nuclear parton distribution functions npdfs, which we call eps09.
A parton distribution function pdf within so called collinear factorization is defined as the probability density for finding a particle with a certain longitudinal momentum fraction x at resolution scale q 2. Ct18 parton distribution functions this page provides numerical table files for the computation of ct18 nexttoleading order nlo and nexttonexttoleading order nnlo parton distribution functions. Todays blog will be the second in a multipart series on replicating excel functions in tsql, continuing with excels norm. Pdf update and comparison of nuclear parton distribution. An important point of this analysis is to show uncertainties of the distributions by the hessian method. Npdf is defined as nuclear parton distribution function very rarely.
In addition nuclear parton distribution functions npdf are critically important for any collider experiment with nuclei e. Continuous distributions are to discrete distributions as type realis to type intin ml. The abbreviation for parton distribution functions is pdf. Nuclear parton distribution function how is nuclear parton distribution function abbreviated.
Sep 29, 2012 central to much phenomenology of highenergy scattering with hadron beams or targets is the concept of a parton density in quantum chromodynamics qcd. Measurements of vector boson production in leadlead and. Introduction parton distribution functions are of great importance in contemporary high energy physics. Q is the density of parton species i per unit of momentum fraction. We use the hessian method to quantify the npdf uncertainties which originate from the uncertainties in the data. Measure total cross section need to know pdfs to be able to test hard part e. These pdfs are released by individual groups as discrete grids as a function of the bjorkenx and energy scale q. Sep 05, 2018 the rise of the parton densities at low \x\ and high \q2\ values is a foundational prediction of qcd derujula et al. Global perturbative qcd analyses, based on large data sets from electronproton and hadron collider experiments, provide tight constraints on the parton distribution function pdf in the proton. Nuclear parton distributions from neural networks vrije.
Parton distribution functions department of physics. Testing nuclear parton distributions with pa collisions at. The possibility of a sizable nonperturbative contribution to the charm parton distribution function pdf in a nucleon is investigated together with theoretical issues arising in its interpretation. In addition, they should be sensitive to the nuclear modification of parton distribution functions npdf.
Nuclear cteq parton distribution functions hepforge. In this paper, we present a detailed study of the unpolarized nucleon parton distribution function pdf employing the approach of parton. Nuclear pdf for neutrino and charged lepton data journal. The usefulness of measuring hard probes in pa collisions, at the lhc in particular, is demonstrated. Sq2, f qpx,q2 and f gpx,q2 to all mix and contribute in the theoretical formulae for all processes.
Parton distribution functions for beginners smu physics. Posepshep2011289 compatibility of global npdf analyses of neutrino dis and chargedlepton dis data j. T1 nuclear parton distributions from neural networks. Guzey b a the pennsylvania state university, 104 davey lab, university park, p a 16802, usa. Cteq6 parton distribution functions are publicly available as a part of the lhapdf fortran library. And most nuclear pdfs are related to a particular proton pdf.
This analysis is based on neutralcurrent deepinelastic structure function data and is performed up to nnlo in qcd calculations with heavy quark mass e ects. Nuclear parton distribution function how is nuclear parton. Npdf nuclear parton distribution function acronymfinder. The parton distribution functions pdfs which describe the hadronic structure of protons and nuclei are the critical link between the experimental data and the proposed theoretical models. Compatibility of global npdf analyses of neutrino dis and chargedlepton dis data j. First contents back conclusion calculation of parton distribution functions craig d. Parton distribution functions and their applications pavel nadolsky department of physics southern methodist university dallas, tx lecture 1 june 19, 2018 pavel nadolsky smu cteq school lecture 1, 20180619 1. One of the meanings of pdf is parton distribution functions what is the abbreviation for parton distribution functions.
Nuclear parton distribution function listed as npdf. A new generation of nlo and lo nuclear parton distribution functions k. Photons and weak bosons do not interact strongly and, thus, their production yields provide direct tests of scaling with a number of binary nucleonnucleon collisions in the heavyion environment. The momentum distribution functions of the partons within the proton. Dist builtin function, thus enshrining my geekdom in the sqlverse forever. Parton distribution functions from ioffe time pseudodistributions. How is nuclear parton distribution function abbreviated.
Here we compare results from two analysis of npdf both done at nexttoleading order in qcd. Testing collinear factorization and nuclear parton. How is neural network parton distribution function abbreviated. Nuclear corrections of parton distribution functions. It generalizes the freeproton pdf framework to determine densities.
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