# ZEU-THEO

 2018-04-2311:20 [PUBDB-2018-01811] Preprint/Report et al Heavy Quark Form Factors at Three Loops in the Planar Limit [DESY-18-052; DO-TH-18-08]   We compute the color-planar and complete light quark non-singlet contributions to the heavy quark form factors in the case of the axialvector, scalar and pseudoscalar currents at three loops in perturbative QCD. We evaluate the master integrals applying a new method based on differential equations for general bases, which is applicable for all first order factorizing systems. [...] OpenAccess: PDF PDF (PDFA); 2018-04-1610:09 [PUBDB-2018-01725] Preprint/Report et al The Variable Flavor Number Scheme at Next-to-Leading Order [DESY-17-187; DO-TH-17-30; arXiv:1804.03129]   We present the matching relations of the variable flavor number scheme at next-to-leading order, which are of importance to define heavy quark partonic distributions for the use at high energy colliders such as Tevatron and the LHC. The consideration of the two-mass effects due to both charm and bottom quarks, having rather similar masses, are important. [...] OpenAccess: PDF PDF (PDFA); 2018-04-1016:08 [PUBDB-2018-01662] Preprint/Report et al The Two-mass Contribution to the Three-Loop Gluonic Operator Matrix Element $A_{gg,Q}^{(3)}$ [DESY 18--016, DO--TH 18/02] We calculate the two-mass QCD contributions to the massive operator matrix element $A_{gg,Q}$ at $\mathcal{O} (\alpha_s^3)$ in analytic form in Mellin $N$- and $z$-space, maintaining the complete dependence on the heavy quark mass ratio. These terms are important ingredients for the matching relations of the variable flavor number scheme in the presence of two heavy quark flavors, such as charm and bottom. [...] Restricted: PDF PDF (PDFA); 2018-03-2310:10 [PUBDB-2018-01534] Preprint/Report Moch, S. NLO PDFs from the ABMP16 fit [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 $\overline{\mathrm{MS}}\,$ renormalization scheme for $\alpha_s$ and all quark masses. [...] OpenAccess: PDF PDF (PDFA); 2018-03-1213:43 [PUBDB-2018-01455] Journal Article/Report/Contribution to a conference proceedings et al Special functions, transcendentals and their numerics [DESY-17-225; arXiv:1712.08541] 13th International Symposium on Radiative Corrections (Applications of Quantum Field Theory to Phenomenology), RADCOR2017, St. GilgenSt. Gilgen, Austria, 25 Sep 2017 - 29 Sep 2017 Proceedings of Science (RADCOR2017), 010 (2017) [10.3204/PUBDB-2018-01455]   Cyclotomic polylogarithms are reviewed and new results concerning the special constants that occur are presented. This also allows some comments on previous literature results using PSLQ.. OpenAccess: PDF PDF (PDFA); 2018-02-1914:58 [PUBDB-2018-01245] Preprint/Report et al Special functions, transcendentals and their numerics [DESY-17-225; arXiv:1712.08541] Cyclotomic polylogarithms are reviewed and new results concerning the special constants that occur are presented. This also allows some comments on previous literature results using PSLQ.. Restricted: PDF PDF (PDFA); 2018-01-1913:34 [PUBDB-2018-00697] Report/Journal Article et al The two-mass contribution to the three-loop pure singlet operator matrix element [DESY-17-195; DO-TH-17-32; arXiv:1711.06717] Nuclear physics / B 927, 339 - 367 (2018) [10.1016/j.nuclphysb.2017.12.018]   We present the two-mass QCD contributions to the pure singlet operator matrix element at three loop order in x-space. These terms are relevant for calculating the structure function $F_2(x,Q^2)$ at $O(\alpha_s^3)$ as well as for the matching relations in the variable flavor number scheme and the heavy quark distribution functions at the same order. [...] OpenAccess: PDF PDF (PDFA); 2018-01-1515:08 [PUBDB-2018-00650] Journal Article/Report/Contribution to a conference proceedings et al Heavy quark form factors at two loops in perturbative QCD [DESY-17-188, DO-TH 17/31, TTK-17-36, NIKHEF 2017-059] XLI International Conference of Theoretical Physics "Matter to the Deepest", PodlesicePodlesice, Poland, 3 Sep 2017 - 8 Sep 2017 Acta physica Polonica / B / Proceedings supplement 48(12), 2155-2166 (2017) [10.5506/APhysPolB.48.2155]   We present the results for heavy quark form factors at two-loop order in perturbative QCD for different currents, namely vector, axial-vector, scalar and pseudo-scalar currents, up to second order in the dimensional regularization parameter. We outline the necessary computational details, ultraviolet renormalization and corresponding universal infrared structure.. Restricted: PDF PDF (PDFA); External link: Fulltext 2018-01-1514:52 [PUBDB-2018-00649] Journal Article/Report/Contribution to a conference proceedings Riemann, T. Scalar one-loop vertex integrals as meromorphic functions of space-time dimension $d$ [KW 17-002, DESY 17-186, DO-TH 17/29] XLI International Conference of Theoretical Physics “Matter to the Deepest”,, PodlesicePodlesice, Poland, 3 Sep 2017 - 8 Sep 2017 Acta physica Polonica / B / Proceedings supplement 48(12), 2313-2320 (2017) [10.5506/APhysPolB.48.2313]   Representations are derived for the basic scalar one-loop vertex Feynman integrals as meromorphic functions of the space-time dimension $d$ in terms of (generalized) hypergeometric functions $_2F_1$ and $F_1$. Values at asymptotic or exceptional kinematic points as well as expansions around the singular points at $d=4+2n$, $n$ non-negative integers, may be derived from the representations easily. [...] Restricted: PDF PDF (PDFA); 2018-01-1508:33 [PUBDB-2018-00635] Preprint/Report et al The Heavy Quark Form Factors at Two Loops [DESY-17-102; DO-TH 17/16; Nikhef 2017-063; TTK-17-44; arXiv:1712.09889]   We compute the two-loop QCD corrections to the heavy quark form factors in case of the vector, axial-vector, scalar and pseudo-scalar currents up to second order in the dimensional parameter $\epsilon = (4-D)/2$. These terms are required in the renormalization of the higher order corrections to these form factors.. OpenAccess: PDF PDF (PDFA);