The CCFM uPDF evolution uPDFevolv

uPDFevolv is an evolution code for TMD parton densities using the CCFM evolution equation. A description of the underlying theoretical model and technical realization is given together with a detailed program description, with emphasis on parameters the user may want to changeComment: Code and description on https://updfevolv.hepforge.org Version to be published in EPJ

TMD parton densities and corresponding parton showers: the advantage of four- and five-flavour schemes

The calculations of $Z + b{\bar b}$ tagged jet production performed in the four- and five-flavour schemes allow for detailed comparison of the heavy flavour structure of collinear and transverse momentum dependent (TMD) parton distributions as well as for detailed investigations of heavy quarks radiated during the initial state parton shower cascade. We have determined the first set of collinear and TMD parton distributions in the four-flavour scheme with NLO DGLAP splitting functions within the Parton-Branching (PB) approach. The four- and five-flavour PB-TMD distributions were used to calculate $Z + b{\bar b}$ tagged jet production at LHC energies and very good agreement with measurements obtained at $\sqrt{s} = 8, 13$ TeV by the CMS and ATLAS collaborations is observed. The different configurations of the hard process in the four- and five-flavour schemes allow for a detailed investigation of the performance of heavy flavor collinear and TMD parton distributions and the corresponding initial TMD parton shower, giving confidence in the evolution of the PB-TMD parton densities as well as in the PB-TMD parton shower

Determination of collinear and TMD photon densities using the Parton Branching method

We present the first determination of transverse momentum dependent (TMD) photon densities with the Parton Branching method. The photon distribution is generated perturbatively without intrinsic photon component. The input parameters for quarks and gluons are determined from fits to precision measurements of deep inelastic scattering cross sections at HERA. The TMD densities are used to predict the mass and transverse momentum spectra of very high mass lepton pairs from both Drell-Yan production and Photon-Initiated lepton processes at the LHC.Comment: 5 pages, 4 figure

Polarized Deeply Inelastic Scattering (DIS) Structure Functions for Nucleons and Nuclei

We extract parton distribution functions (PDFs) and structure functions from recent experimental data of polarized lepton-DIS on nucleons at next-to-leading order (NLO) Quantum Chromodynamics. We apply the Jacobi polynomial method to the DGLAP evolution as this is numerically efficient. Having determined the polarized proton and neutron spin structure, we extend this analysis to describe 3He and 3H polarized structure functions, as well as various sum rules. We compare our results with other analyses from the literature.Comment: LaTeX, 12 pages, 11 figures, 6 tables. Update to match published versio

On the role of soft gluons in collinear parton densities

The role of soft (non-perturbative) gluons in collinear parton densities is investigated with the Parton Branching method as a solution of the DGLAP evolution equations. It is found that soft gluons contribute significantly to collinear parton densities. Within the Parton Branching frame, the Sudakov form factor can be split into a perturbative and non-perturbative part. The non-perturbative part can be calculated analytically under certain conditions. It is shown that the inclusion of soft (non-perturbative) gluons to the parton density evolution is essential for the proper cancellation of divergent terms. It is argued that the non-perturbative part of the Sudakov form factor has its correspondence in Transverse Momentum Dependent parton distributions. Within the Parton Branching approach, this non-perturbative Sudakov form factor is constrained by fits of inclusive, collinear parton densities. We show that the non-perturbative Sudakov form factor and soft gluon emissions are essential for inclusive distributions (collinear parton densities and Drell-Yan transverse momentum spectra), while those soft gluons play essentially no role in final state hadron spectra.Comment: Significantly updated including studies on parton shower and hadronizatio

Nucleon spin structure functions at NNLO in the presence of target mass corrections and higher twist effects

We extract polarized parton distribution functions (PPDFs), referred to as “KTA17,” together with the highly correlated strong coupling αs from recent and up-to-date g1 and g2 polarized structure functions world data at next-to-next-to-leading order in perturbative QCD. The stability and reliability of the results are ensured by including nonperturbative target mass corrections as well as higher-twist terms which are particularly important at the large-x region at low Q2. Their role in extracting the PPDFs in the nucleon is studied. Sum rules are discussed and compared with other results from the literature. This analysis is made by means of the Jacobi polynomials expansion technique to the DGLAP evolution. The uncertainties on the observables and on the PPDFs throughout this paper are computed using standard Hessian error propagation which served to provide a more realistic estimate of the PPDFs uncertainties

Study of spin-dependent structure functions of 3He and 3H at NNLO approximation and corresponding nuclear corrections

We determine polarized parton distribution functions (PPDFs) and structure functions from recent experimental data of polarized deep inelastic scattering (DIS) on nucleons at next-to-next-to-leading order (NNLO) approximation in perturbative quantum chromodynamics (pQCD). The nucleon polarized structure functions are computed using the Jacobi polynomial approach while target mass corrections (TMCs) are included in our fitting procedure. Having extracted the polarized spin structure functions, we extend our study to describe 3He and 3H polarized structure functions, as well as the Bjorken sum rule. We also explore the importance of the nuclear corrections on the polarized nuclear structure functions at small and large values of x . Our results are compared with the recent available and high precision polarized 3He and 3H experimental data

Polarized Deeply Inelastic Scattering (DIS) Structure Functions for Nucleons and Nuclei

We extract parton distribution functions (PDFs) and structure functions from recent experimental data of polarized lepton-DIS on nucleons at next-to-leading order (NLO) Quantum Chromodynamics. We apply the Jacobi polynomial method to the DGLAP evolution as this is numerically efficient. Having determined the polarized proton and neutron spin structure, we extend this analysis to describe 3He and 3H polarized structure functions, as well as various sum rules. We compare our results with other analyses from the literature.Comment: LaTeX, 12 pages, 11 figures, 6 tables. Update to match published versio