National police defense foundation how is national police. Testing collinear factorization and nuclear parton. This analysis is based on neutralcurrent deepinelastic structure function data and is performed up to nnlo in qcd calculations with heavy quark mass effects. 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. Compatibility of global npdf analyses of neutrino dis and chargedlepton dis data j.
This article explains the definition of parton densities also called parton distribution functions. Nuclear cteq parton distribution functions hepforge. Update and comparison of nuclear parton dis tribution. Global perturbative qcd analyses, based on large data sets from ep and hadron collider experiments, provide tight constraints on the parton distribut. Sq2, f qpx,q2 and f gpx,q2 to all mix and contribute in the theoretical formulae for all processes. The model uncertainties are related to the assumptions made in pdf. Nuclear parton distribution function how is nuclear parton distribution function abbreviated. Citeseerx eps09 global nlo analysis of nuclear pdfs and.
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. We parametrize these effects by nuclear parton distribution functions npdf. Npdfs can help to understand the impact of high twist contributions on dis structure functions at low and moderate q2. 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. Q where i labels the parton species depends on two variables.
A new generation of nlo and lo nuclear parton distribution functions k. Parton distribution functions pdfs, which are universal characteristics of the target at high momentum transfer q2 driven by nonperturbative strong interactions. Dy in order to determine optimum parton distribution functions pdfs in nuclei. We report global analysis results of experimental data for nuclear structure function ratios fa2fa. 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. A code for carrying out the leadingorder evolution of such pdfs. Nuclear parton distribution function how is nuclear. Measurements of vector boson production in leadlead and. Nuclear corrections of parton distribution functions. Nuclear pdf for neutrino and charged lepton data journal.
An important point of this analysis is to show uncertainties of the distributions by the hessian method. Compatibility of global npdf analyses of neutrino dis and. We present a first determination of the nuclear parton distribution functions npdf based on the nnpdf methodology. 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. In this talk, we present our recent nexttoleading order nlo nuclear parton distribution functions npdfs, which we call eps09. Nuclear parton distributions from leptonnucleus scattering. Uncertainties of parton distribution functions slac. There is however not a unique set of parton distribution functions commonly accepted. Therefore we must sometimes use physics judgement in producing the pdf model, as an aid to the objec tive fitting procedures. Introduction to parton distribution functions scholarpedia. Nuclei are loosely bound systems with binding energy e b.
National police defense foundation how is national. Heavy target data essential for determining separate parton flavors. The nuclear parton distribution functions npdf differ in magnitude from the pdf of the free proton. 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. A parton distribution function pdf within so called collinear factorization is defined as the probability density. Parton distribution functions and their applications.
Parton distribution functions from ioffe time pseudodistributions. Opensource qcd analysis of nuclear parton distribution. 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. The dglapanalyses of the nuclear parton distribution functions npdf based on the global. 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. 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.
Parton distribution functions department of physics. Description this package gives nuclear parton distribution functions npdfs of various nuclei starting from low q2 0. Nuclear parton distribution function listed as npdf. 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. T1 nuclear parton distributions from neural networks. Npdf is defined as nuclear parton distribution function very rarely. The cteq6 family of pdfs is superseded by newer, more complete, ct10 pdf sets. In this paper, we present a detailed study of the unpolarized nucleon parton distribution function pdf employing the approach of parton. How is neural network parton distribution function abbreviated. May 14, 2015 excel in tsql part 2 the normal distribution norm.
Cteq collaborative effort to determine parton distribution functions inside of a free proton. Nnpdf is defined as neural network parton distribution function somewhat frequently. Q is the density of parton species i per unit of momentum fraction. 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. The extension of these analyses to nuclear parton distribution functions npdfs has attracted much interest in recent years. Dist builtin function, thus enshrining my geekdom in the sqlverse forever. Godat, eric, the impact of ppb wz lhc data on ncteq15 parton distribution functions with an emphasis on refitting the ncteq15 npdf set 2018. 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. Protonlead collisions also provide an excellent opportunity to test npdf in a less dense. In addition nuclear parton distribution functions npdf are critically important for any collider experiment with nuclei e. This page provides numerical table files for the computation of ct18 nexttoleading order nlo and nexttonexttoleading order nnlo parton distribution functions. The usefulness of measuring hard probes in pa collisions, at the lhc in particular, is demonstrated. Pdf update and comparison of nuclear parton distribution.
Nuclear parton distribution function how is nuclear parton. Parton distribution functions pdfs are essential nonperturbative inputs for calculation of any observable with hadronic initial states. In addition, they should be sensitive to the nuclear modification of parton distribution functions npdf. Introduction parton distribution functions are of great importance in contemporary high energy physics. A dis are not compatible with the predictions derived from. Double parton scattering may constitute a signi cant background to important processes such as higgs boson production. One of the meanings of pdf is parton distribution functions what is the abbreviation for parton distribution functions. We use the hessian method to quantify the npdf uncertainties which originate from the uncertainties in the data. Proton pdf are determined from data taken not only on protons but from some data. These pdfs are released by individual groups as discrete grids as a function of the bjorkenx and energy scale q. Global analyses of nuclear parton distribution functions npdfs. 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. A parton distribution function pdf within so called collinear factorization is defined as the probability density for. How is nuclear parton distribution function abbreviated.
Nuclear pdf for neutrino and charged lepton data nasaads. Parton distribution functions definition scholarpedia. Guzey b a the pennsylvania state university, 104 davey lab, university park, p a 16802, usa. Eps09 a new generation of nlo and lo nuclear parton. The production of z bosons in ppb collisions at snn5. N2 in this contribution, we present a status report on the recent progress towards an analysis of nuclear parton distribution functions npdfs. Here we compare results from two analysis of npdf both done at nexttoleading order in qcd. An introduction to the pdf determination by global analyses of the main pdf fitting groups with an emphasis on hera pdfs is presented. We present a rst determination of the nuclear parton distribution functions npdf based on the nnpdf methodology. Npdf nuclear parton distribution function acronymfinder. Npdf stands for nuclear parton distribution function. 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. The extension of these analyses to nuclear parton distributions npdf has attracted much interest in recent years. The impact of ppb wz lhc data on ncteq15 parton distribution.
Posepshep2011289 compatibility of global npdf analyses of neutrino dis and chargedlepton dis data j. Nnpdf stands for neural network parton distribution function. Continuous distributions are to discrete distributions as type realis to type intin ml. Nlo global dglap analysis of nuclear parton distribution functions npdfs and their uncertainties.
Testing nuclear parton distributions with pa collisions at. Nuclear parton distribution function npdf 10 how do we extract the medium effect in pbpb collisions. A deep inelastic scattering dis, chargedleptonnucleus. Citeseerx document details isaac councill, lee giles, pradeep teregowda. Theory experimental observables pdf parametrizations statistical aspects practical applications. Nuclear parton distributions from neural networks vrije. 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. Measure total cross section need to know pdfs to be able to test hard part e. The abbreviation for parton distribution functions is pdf. Parton distribution functions can be abbreviated as pdf. We report global analysis results of experimental data for nuclear structurefunction ratios fa2fa. Carrying out an nlo npdf analysis for the first time with three different types of experimental input deep inelastic. Nuclear corrections of parton distribution functions arxiv. Npdf is listed in the worlds largest and most authoritative dictionary database of abbreviations and acronyms.
Cteq6 parton distribution functions are publicly available as a part of the lhapdf fortran library. Todays blog will be the second in a multipart series on replicating excel functions in tsql, continuing with excels norm. In order to use neutrino dis data in a global analysis of proton pdfs nuclear effects need to be understood. Parton distribution functions for beginners smu physics. 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. It generalizes the freeproton pdf framework to determine densities.
The curves were obtained using the pdfs from the herapdf analysis 14. 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. We present a nexttoleading order nlo global dglap analysis of nuclear parton distribution functions npdfs and their uncertainties. We perform a global chi2analysis of nuclear parton distribution functions using data from charged current neutrinonucleus deepinelastic scattering dis.
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