We present nonperturbative fragmentation functions (FFs) for bottom-flavored (B) hadrons both at next-to-leading (NLO) and, for the first time, at next-to-next-to-leading order (NNLO) in the MS factorization scheme with five massless quark flavors. They are determined by fitting all available experimental data of inclusive single B-hadron production in e + e − annihilation, from the ALEPH, DELPHI, and OPAL Collaborations at CERN LEP1 and the SLD Collaboration at SLAC SLC. The uncertainties in these FFs as well as in the corresponding observables are estimated using the Hessian approach. We perform comparisons with available NLO sets of B-hadron FFs. We apply our new FFs to generate theoretical predictions for the energy distribution of B hadrons produced through the decay of unpolarized or polarized top quarks, to be measured at the CERN LHC.

Precise knowledge of the strange and antistrange quark distributions of the nucleon is a major step toward better understanding of the strong interaction and the nucleon structure. Moreover, the s −s asymmetry in the nucleon plays an important role in some physical processes involving hadrons. The goal of this paper is the study of intrinsic strange contribution to the strange sea of the nucleon. To this aim, we calculate the intrinsic strange distributions from the various light-cone models, including Brodsky, Hoyer, Peterson, and Sakai (BHPS); scalar five-quark and meson-baryon models and then compare their results. These models can lead to the rather different distributions for the intrinsic strange that are dominated in different values of x. Furthermore, the meson-baryon model leads to the s−s asymmetry that can be comparable in some situations to the result obtained from the global analysis of PDFs. We also present a simple parametrization for each model prediction of intrinsic strange distribution.

In this paper, we present "SMKA18" analysis which is a first attempt to extract the set of nextto-next-leading-order (NNLO) spin-dependent parton distribution functions (spin-dependent PDFs) and their uncertainties determined through the Laplace transform technique and Jacobi polynomial approach. Using the Laplace transformations, we present an analytical solution for the spindependent Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations at NNLO approximation. The results are extracted using a wide range of proton g p 1 (x, Q 2 ), neutron g n 1 (x, Q 2 ) and deuteron g d 1 (x, Q 2 ) spin-dependent structure functions dataset including the most recent high-precision measurements from COMPASS16 experiments at CERN which are playing an increasingly important role in global spin-dependent fits. The careful estimations of uncertainties have been done using the standard "Hessian error" propagation. We will compare our results with the available spin-dependent inclusive deep inelastic scattering dataset and other results for the spin-dependent PDFs in literature.The results obtained for the spin-dependent PDFs as well as spin-dependent structure functions are clearly explained both in the small and large values of x.

The main aim of this paper is to present new sets of non-perturbative fragmentation functions (FFs) for D 0 and D + mesons at next-to-leading (NLO) and, for the first time, at next-to-next-toleading order (NNLO) in the MS factorization scheme with five massless quark flavors. This new determination of FFs is based on the QCD fit to the OPAL experimental data for hadron production in the electron-positron single-inclusive annihilation (SIA). We discuss in detail the novel aspects of the methodology used in our analysis and the validity of obtained FFs by comparing with previous works in literature which have been carried out up to NLO accuracy. We will also incorporate the effect of charmed meson mass corrections into our QCD analysis and discuss the improvements upon inclusion of these effects. The uncertainties in the extracted FFs as well as in the corresponding observables are estimated using the "Hessian" approach. For a typical application, we use our new FFs to make theoretical predictions for the energy distributions of charmed mesons inclusively produced through the decay of unpolarized top quarks, to be measured at the CERN LHC. As a result of this analysis, suggestions are discussed for possible future studies on the current topic to consider any theory improvements and other available experimental observables.

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The experimental data taken from both Drell-Yan and deep-inelastic scattering (DIS) experiments suggest a sign-change ind(x) −ū(x) flavor asymmetry in the proton at large values of momentum fraction x. In this work, we present a phenomenological study ofd(x)−ū(x) flavor asymmetry. First, we extract thed(x) −ū(x) distribution using the more recent data from the BONuS experiment at Jefferson Lab on the ratio of neutron to proton structure functions, F n 2 /F p 2 , and show that it undergoes a sing-change and becomes negative at large values of momentum fraction x, as expected. The stability and reliability of our obtained results have been examined by including target mass corrections (TMCs) as well as higher twist (HT) terms which are particularly important at the large-x region at low Q 2 . Then, we calculate thed(x) −ū(x) distribution using the Brodsky, Hoyer, Peterson, and Sakai (BHPS) model and show that if one chooses a mass for the down quark smaller than the one for the up quark it leads to a better description for the Fermilab E866 data. In order to prove this claim, we determine the masses of down and up sea quarks by fitting to the available and up-to-date experimental data for thed(x) −ū(x) distribution. In this respect, unlike the previous performed theoretical studies, we have shown that this distribution has a sign-change at x > 0.3 after evolution to the scale of available experimental data.

In this work, using the Laplace transformation technique we present our results for nonsinglet quark distributions as well as nucleon structure function F2(x, Q 2 ) in unpolarized case at next-tonext-to-leading order (NNLO) QCD approximation. We shall particularly compare our results for the sets of valence-quark parton distribution functions with the contemporary collaborations like CT14, MMHT14, MKAM16 and NNPDF groups. In our analysis, to construct the nucleon structure function we employ the Jacobi polynomials expansion which is suitable to convert the results for nonsinglet structure function from the Laplace s-space to Bjorken x-space. We shall also consider the contributions of target mass correction as well as the higher twist effects at large x region for the proton and deuteron structure function. Our results for the unpolarized quark distribution functions and nucleon structure functions are in good agreement with both recent theoretical models and available experimental data.

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