ZEU-THEO

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2017-06-19
13:43
OpenAccess [PUBDB-2017-05452] Report/Journal Article
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On ${\gamma }_{5}$ in higher-order QCD calculations and the NNLO evolution of the polarized valence distribution
[DESY-15-061; NIKHEF-15-018; LTH-1042; arXiv:1506.04517] ddc:530
We discuss the prescription for the Dirac matrix ${\gamma }_{5}$ in dimensional regularization used in most second- and third-order QCD calculations of collider cross sections. We provide an alternative implementation of this approach that avoids the use of an explicit form of ${\gamma }_{5}$ and of its (anti-) commutation relations in the most important case of no more than one ${\gamma }_{5}$ in each fermion trace. [...]
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2017-06-14
14:42
OpenAccess [PUBDB-2017-04944] Report/Journal Article
; ; ; et al
Asymptotic 3-loop heavy flavor corrections to the charged current structure functions $F^{W^{+}-W^{-}}_{L}(x,Q^{2})$ and $F^{W^{+}-W^{-}}_{2}(x,Q^{2})$
[DESY-16-148; DO-TH-16-15; arXiv:1609.06255] ddc:530
We calculate the massive Wilson coefficients for the heavy flavor contributions to the non-singlet charged current deep-inelastic scattering structure functions $F_L^{W^+}(x,Q^2)-F_L^{W^-}(x,Q^2)$ and $F_2^{W^+}(x,Q^2)-F_2^{W^-}(x,Q^2)$ in the asymptotic region $Q^2 \gg m^2$ to 3-loop order in Quantum Chromodynamics (QCD) at general values of the Mellin variable $N$ and the momentum fraction $x$. Besides the heavy quark pair production, also the single heavy flavor excitation $s \rightarrow c$ contributes. [...]
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2017-06-13
16:14
OpenAccess [PUBDB-2017-04838] Preprint/Report
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Refined Holonomic Summation Algorithms in Particle Physics
[DESY-17-087; DO-TH-17-09; arXiv:1706.03677]
 GO
An improved multi-summation approach is introduced and discussed that enables one to simultaneously handle indefinite nested sums and products in the setting of difference rings and holonomic sequences. Relevant mathematics is reviewed and the underlying advanced difference ring machinery is elaborated upon. [...]
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2017-06-06
13:38
OpenAccess [PUBDB-2017-04322] Report/Journal Article
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The method of arbitrarily large moments to calculate single scale processes in quantum field theory
[DESY-17-009; DO-TH 17-01; arXiv:1701.04614] ddc:530
We device a new method to calculate a large number of Mellin moments of single scale quantities using the systems of differential and/or difference equations obtained by integration-by-parts identities between the corresponding Feynman integrals of loop corrections to physical quantities. These scalar quantities have a much simpler mathematical structure than the complete quantity. [...]
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2017-06-06
11:46
OpenAccess [PUBDB-2017-04277] Preprint/Report
; ; ; et al
Three Loop Massive Operator Matrix Elements and Asymptotic Wilson Coefficients with Two Different Masses
[DESY-14-019; DO-TH-15-08; arXiv:1705.07030]
 GO
Starting at 3-loop order, the massive Wilson coefficients for deep-inelastic scattering and the massive operator matrix elements describing the variable flavor number scheme receive contributions of Feynman diagrams carrying quark lines with two different masses. In the case of the charm and bottom quarks, the usual decoupling of one heavy mass at a time no longer holds, since the ratio of the respective masses, $\eta = m_c^2/m_b^2 \sim 1/10$, is not small enough. [...]
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2017-06-06
11:38
OpenAccess [PUBDB-2017-04273] Preprint/Report
; ; ; et al
Iterated Elliptic and Hypergeometric Integrals for Feynman Diagrams
[DESY-16-147; DO-TH-16-14; arXiv:1706.01299]
 GO
We calculate 3-loop master integrals for heavy quark correlators and the 3-loop QCD corrections to the $\rho$-parameter. They obey non-factorizing differential equations of second order with more than three singularities, which cannot be factorized in Mellin-$N$ space either. [...]
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2017-05-22
15:43
OpenAccess [PUBDB-2017-03382] Report/Journal Article
; ; ; et al
Complete renormalization of QCD at five loops
[BI-TP-2017-01; DESY-17-011; IPPP-17-7; arXiv:1701.07068] ddc:530
We present new analytical five-loop Feynman-gauge results for the anomalous dimensions of ghost field and -vertex, generalizing the known values for SU(3) to a general gauge group. Together with previously published results on the quark mass and -field anomalous dimensions and the Beta function, this completes the 5-loop renormalization program of gauge theories in that gauge..
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2017-05-08
10:59
OpenAccess [PUBDB-2017-02352] Preprint/Report

Muon $g - 2$ Theory: the Hadronic Part
[DESY-17-058; HU-EP-17-12; arXiv:1705.00263]
 GO
I present a status report of the hadronic vacuum polarization effects for the muon $g-2$, to be considered as an update of [1]. The update concerns recent new inclusive $R$ measurements from KEDR in the energy range 1.84 to 3.72 GeV. [...]
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2017-04-21
13:38
OpenAccess [PUBDB-2017-01782] Preprint/Report
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The 3-Loop Splitting Functions $P_{qg}^{(2)}$ and $P_{gg}^{(2,\rm N_F)}$
[DESY-17-062; DO-TH-17-05; MSUHEP-17-004; MITP-17-033; TTK-17-13; arXiv:1705.01508]
 GO
We calculate the unpolarized twist-2 three-loop splitting functions $P_{qg}^{(2)}(x)$ and$P_{gg}^{(2,\rm N_F)}(x)$ and the associated anomalous dimensions using massive 3-loopoperator matrix elements. While we calculate $P_{gg}^{(2,\rm N_F)}(x)$ directly, $P_{qg}^{(2)}(x)$is computed from 973 even moments, without any structural prejudice, using a hierarchy ofrecurrences obtained for the corresponding operator matrix element. [...]
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2017-02-01
09:03
OpenAccess [PUBDB-2017-00818] Preprint/Report
; ; ; et al
Complete renormalization of QCD at five loops
[BI-TP-2017-01; DESY-17-011; IPPP-17-7; arXiv:1701.07068]
 GO
We present new analytical five-loop Feynman-gauge results for the anomalous dimensions of ghost field and -vertex, generalizing the known values for SU(3) to a general gauge group. Together with previously published results on the quark mass and -field anomalous dimensions and the Beta function, this completes the 5-loop renormalization program of gauge theories in that gauge..
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