3,724 research outputs found
Low-energy moments of non-diagonal quark current correlators at four loops
We compute the leading four physical terms in the low-energy expansions of
heavy-light quark current correlators at four-loop order. As a by-product we
reproduce the corresponding top-induced non-singlet correction to the
electroweak rho parameter.Comment: 13 pages, no figures. Extended discussion and added reference
Five-Loop Static Contribution to the Gravitational Interaction Potential of Two Point Masses
We compute the static contribution to the gravitational interaction potential
of two point masses in the velocity-independent five-loop (and 5th
post-Newtonian) approximation to the harmonic coordinates effective action in a
direct calculation. The computation is performed using effective field methods
based on Feynman diagrams in momentum-space in space
dimensions. We also reproduce the previous results including the 4th
post-Newtonian order.Comment: 15 pages, 4 figure
Higher-order hadronic and heavy-lepton contributions to the anomalous magnetic moment
We report about recent results obtained for the muon anomalous magnetic
moment. Three-loop kernel functions have been computed to obtain the
next-to-next-to-leading-order hadronic vacuum polarization contributions. The
numerical result, , is of
the same order of magnitude as the current uncertainty from the hadronic
contributions. For heavy-lepton corrections, analytical results are obtained at
four-loop order and compared with the known results.Comment: Contribution to the proceedings of Loops and Legs in Quantum Field
Theory, 27 April - 2 May 2014, Weimar, German
Hadronic contribution to the muon anomalous magnetic moment to next-to-next-to-leading order
We compute the next-to-next-to-leading order hadronic contribution to the
muon anomalous magnetic moment originating from the photon vacuum polarization.
The corresponding three-loop kernel functions are calculated using asymptotic
expansion techniques which lead to analytic expressions. Our final result,
, has the same order of
magnitude as the current uncertainty of the leading order hadronic contribution
and should thus be included in future analyses.Comment: 9 pages,v2: note on NLO hadronic light-by-light contribution added,
matches published version, Physics Letters B 734 (2014) 144-14
Massive three loop form factors in the planar limit
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. The analytic results are expressed in
terms of harmonic polylogarithms and real-valued cyclotomic harmonic
polylogarithms.Comment: 10 pages; Proceedings of the Loops and Legs in Quantum Field Theory,
29th April 2018 - 4th May 2018, St. Goar, Germany; Report number modifie
The three-loop cusp anomalous dimension in QCD
We present the full analytic result for the three-loop angle-dependent cusp
anomalous dimension in QCD. With this result, infrared divergences of planar
scattering processes with massive particles can be predicted to that order.
Moreover, we define a closely related quantity in terms of an effective
coupling defined by the light-like cusp anomalous dimension. We find evidence
that this quantity is universal for any gauge theory, and use this observation
to predict the non-planar -dependent terms of the four-loop cusp
anomalous dimension.Comment: 5 pages, 2 figure
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