2,000 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
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
The terms of the three-loop cusp anomalous dimension in QCD
In this talk we present the result for the dependent piece of the
three-loop cusp anomalous dimension in QCD. Remarkably, it is parametrized by
the same simple functions appearing in analogous anomalous dimensions in
SYM at one and two loops. We also compute all required master
integrals using a recently proposed refinement of the differential equation
method. The analytic results are expressed in terms of harmonic polylogarithms
of uniform weight.Comment: 8 pages, 2 figures; v2: typo in eq. (4.4) fixed, 'three-loop' added
to titl
Determination of Spin and CP of the Higgs Boson from WBF
We explore the possibilities to determine the spin/CP properties of the Higgs
boson at the LHC. To cover the mass region below the ZZ threshold we make use
of the properties of the production in Weak Boson Fusion (WBF) and the decay
chain H -> WW -> l nu l nu. In particular, we study the angular correlations of
the forward jets and the distribution of the invariant mass of the lepton pair
for different hypothetical Higgs like particles
The parameter at three loops and elliptic integrals
We describe the analytic calculation of the master integrals required to
compute the two-mass three-loop corrections to the parameter. In
particular, we present the calculation of the master integrals for which the
corresponding differential equations do not factorize to first order. The
homogeneous solutions to these differential equations are obtained in terms of
hypergeometric functions at rational argument. These hypergeometric functions
can further be mapped to complete elliptic integrals, and the inhomogeneous
solutions are expressed in terms of a new class of integrals of combined
iterative non-iterative nature.Comment: 14 pages Latex, 7 figures, to appear in the Proceedings of "Loops and
Legs in Quantum Field Theory - LL 2018", 29 April - 4 May 2018, Po
Completely automated computation of the heavy-fermion corrections to the three-loop matching coefficient of the vector current
We evaluate the corrections to the matching coefficient of the vector current
between Quantum Chromodynamics (QCD) and Non-Relativistic QCD (NRQCD) to
three-loop order containing a closed heavy-fermion loop. The result constitutes
a building block both for the bottom- and top-quark system at threshold. Strong
emphasis is put on our completely automated approach of the calculation
including the generation of the Feynman diagrams, the identification of the
topologies, the reduction to master integrals and the automated numerical
computation of the latter.Comment: 14 page
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