20180618 16:24 
[PUBDB201802323]
Journal Article
Maier, A. ; Marquard, P.
Validity of Padé approximations in vacuum polarization at three and fourloop order
The heavyquark contribution to the polarization function Π at higher perturbative orders is presently only known approximately. We scrutinize the accuracy of stateoftheart approximations at three and fourloop order [...]
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ddc:530
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20180604 14:58 
[PUBDB201802179]
Report/Journal Article
Ablinger, J. ; Blümlein, J. ; De Freitas, A. ; et al
The Twomass Contribution to the ThreeLoop Gluonic Operator Matrix Element $A_{gg,Q}^{(3)}$
[DESY18016; DOTH1802; arXiv:1804.02226]
We calculate the twomass 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. [...]
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ddc:530
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20180604 14:51 
[PUBDB201802178]
Report/Journal Article
Ablinger, J. ; Behring, A. ; Blümlein, J. ; et al
Heavy quark form factors at two loops
[DESY17102; DOTH1716; Nikhef2017063; TTK1744; arXiv:1712.09889]
We compute the twoloop QCD corrections to the heavy quark form factors in case of the vector, axialvector, scalar and pseudoscalar currents up to second order in the dimensional parameter $\epsilon = (4D)/2$. These terms are required in the renormalization of the higher order corrections to these form factors..
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ddc:530
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20180601 09:46 
[PUBDB201802167]
Journal Article
Blümlein, J. ; De Freitas, A. ; Schneider, C. ; et al
The variable flavor number scheme at nexttoleading order
We present the matching relations of the variable flavor number scheme at nexttoleading 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 twomass effects due to both charm and bottom quarks, having rather similar masses, are important [...]
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ddc:530
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20180528 14:41 
[PUBDB201802123]
Preprint/Report
Chetyrkin, K. ; Falcioni, G. ; Herzog, F. ; et al
Fiveloop renormalisation of QCD in covariant gauges
[DESY17144; Nikhef201742; arXiv:1709.08541]
We present the complete set of vertex, wave function and charge renormalisation constants in QCD in a general simple gauge group and with the complete dependence on the covariant gauge parameter ξ in the minimal subtraction scheme of conventional dimensional regularisation. Our results confirm all already known results, which were obtained in the Feynman gauge, and allow the extraction of other useful gauges such as the Landau gauge. [...]
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ddc:540
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20180502 10:39 
[PUBDB201801884]
Preprint/Report
Jegerlehner, F.
The Muon g2 in Progress
[DESY18057; HUEP1811; arXiv:1804.07409]
Two next generation muon $g2$ experiments at Fermilab in the US and at JPARC in Japan have been designed to reach a four times better precision from 0.54 ppm to 0.14 ppm and the challenge for the theory side is to keep up in precision as far as possible. This has triggered a lot of new research activities. [...]
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20180423 11:20 
[PUBDB201801811]
Preprint/Report
Ablinger, J. ; Blümlein, J. ; Marquard, P. ; et al
Heavy Quark Form Factors at Three Loops in the Planar Limit
[DESY18052; DOTH1808]
We compute the colorplanar and complete light quark nonsinglet 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. [...]
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20180416 10:09 
[PUBDB201801725]
Preprint/Report
Blümlein, J. ; De Freitas, A. ; Schneider, C. ; et al
The Variable Flavor Number Scheme at NexttoLeading Order
[DESY17187; DOTH1730; arXiv:1804.03129]
We present the matching relations of the variable flavor number scheme at nexttoleading 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 twomass effects due to both charm and bottom quarks, having rather similar masses, are important. [...]
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20180410 16:08 
[PUBDB201801662]
Preprint/Report
Ablinger, J. ; Blümlein, J. ; Freitas, A. d. ; et al
The Twomass Contribution to the ThreeLoop Gluonic Operator Matrix Element $A_{gg,Q}^{(3)}$
[DESY18016; DOTH1802; arXiv:1804.02226]
We calculate the twomass 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. [...]
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20180323 10:10 
[PUBDB201801534]
Preprint/Report
Alekhin, S. ; Blümlein, J. ; Moch, S.
NLO PDFs from the ABMP16 fit
[DESY18026; DOTH 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 nexttoleading order (NLO) in QCD. The analysis applies the $\overline{\mathrm{MS}}\, $ renormalization scheme for $\alpha_s$ and all quark masses. [...]
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