# ZEU-THEO

 2018-09-2111:17 [PUBDB-2018-03555] Preprint/Report et al Numerical Implementation of Harmonic Polylogarithms to Weight w = 8 [DESY-13-064; DO-TH-17-12; arXiv:1809.07084]   We present the FORTRAN-code HPOLY.f for the numerical calculation of harmonic polylogarithms up to w = 8 at an absolute accuracy of $\sim 4.9 \cdot 10^{-15}$ or better. Using algebraic and argument relations the numerical representation can be limited to the range $x \in [0, \sqrt{2}-1]$. [...] OpenAccess: PDF PDF (PDFA); 2018-09-2010:28 [PUBDB-2018-03546] Journal Article/Report Moch, S. -. NNLO PDFs for the LHC [DESY-18-150; DO-TH-18-19; arXiv:1808.08404] Loops and Legs in Quantum Field Theory, LL2018, Meeting location, Proceedings of Science ???, ??? (2018) [10.3204/PUBDB-2018-03372]   We consider some trends, achievements and a series of remaining problems in the precision determination of parton distribution functions. For the description of the scaling violations of the deep-inelastic scattering data, forming the key ingredients to all PDF fits, a solid theoretical framework is of importance [...] External link: Fulltext 2018-09-1810:46 [PUBDB-2018-03526] Preprint/Report Schneider, C. Computer algebra tools for Feynman integrals and related multi-sums [DESY-18-160; DO-TH-18-21; arXiv:1809.06168]   In perturbative calculations, e.g., in the setting of Quantum Chromodynamics (QCD) one aims at the evaluation of Feynman integrals. Here one is often faced with the problem to simplify multiple nested integrals or sums to expressions in terms of indefinite nested integrals or sums. [...] OpenAccess: PDF PDF (PDFA); 2018-09-0511:44 [PUBDB-2018-03385] Preprint/Report et al The $\rho$ parameter at three loops and elliptic integrals [DESY-18-117; DO-TH-18-15; arXiv:1807.05287]   We describe the analytic calculation of the master integrals required to compute the two-mass three-loop corrections to the $\rho$ parameter. In particular, we present the calculation of the master integrals for which the corresponding differential equations do not factorize to first order. [...] OpenAccess: PDF PDF (PDFA); 2018-09-0509:55 [PUBDB-2018-03372] Preprint/Report Moch, S. O. NNLO PDFs for the LHC [DESY-18-150; DO-TH-18-19; arXiv:1808.08404] Seminar, Meeting location, Contributions / Info   We consider some trends, achievements and a series of remaining problems in the precision determination of parton distribution functions. For the description of the scaling violations of the deep-inelastic scattering data, forming the key ingredients to all PDF fits, a solid theoretical framework is of importance [...] OpenAccess: PDF PDF (PDFA); 2018-09-0509:47 [PUBDB-2018-03370] Preprint/Report et al Massive three loop form factors in the planar limit [DESY-18-118; DO-TH-18-14; arXiv:1807.05943]   We present the color planar and complete light quark QCD contributions to the three loop heavy quark form factors in the case of vector, axial-vector, scalar and pseudo-scalar currents. We evaluate the master integrals applying a new method based on differential equations for general bases, which is applicable for any first order factorizing systems. [...] OpenAccess: PDF PDF (PDFA); 2018-08-2714:18 [PUBDB-2018-03195] Preprint/Report Blümlein, J. Iterative Non-iterative Integrals in Quantum Field Theory [DESY-18-143; DO-TH-17-08; arXiv:1808.08128]   Single scale Feynman integrals in quantum field theories obey difference or differential equations with respect to their discrete parameter $N$ or continuous parameter $x$. The analysis of these equations reveals to which order they factorize, which can be different in both cases. [...] OpenAccess: PDF PDF (PDFA); 2018-08-2713:24 [PUBDB-2018-03190] Preprint/Report et al Strange and non-strange distributions from the collider data [DESY-18-144; DO-TH-18-18; arXiv:1808.06871]   We check the stability of the ABMP16 fit with respect to modifications of quark PDFs suggested in the recent literature: the strange sea enhancement and a positive non-vanishing $d/u$ ratio at $x \to 1$. These possibilities are examined using test versions of the ABMP16 PDF fit which demonstrate no need of those changes. [...] OpenAccess: PDF PDF (PDFA); 2018-08-0709:49 [PUBDB-2018-02763] Preprint/Report et al Two-mass three-loop effects in deep-inelastic scattering [DESY-18-119; DO-TH-18-16; arXiv:1807.07855]   We report on recent results on the two-mass corrections for massive operator matrix elements at 2- and 3-loop orders in QCD. These corrections form the building blocks of the variable flavor number scheme. [...] OpenAccess: PDF PDF (PDFA); 2018-08-0114:57 [PUBDB-2018-02739] Report/Journal Article Moch, S.-O. NLO PDFs from the ABMP16 fi [DESY-18-026; DO-TH-17-28; arXiv:1803.07537]   We perform a global fit of parton distribution functions (PDFs) together with the strong coupling constant $\alpha_s$ and the quark masses $m_c, m_b$ and $m_t$ at next-to-leading order (NLO) in QCD. The analysis applies the $\overline{MS}$ renormalization scheme for αs and all quark masses. [...] OpenAccess: PDF PDF (PDFA);