924 research outputs found
Leptonic contributions to the effective electromagnetic coupling at four-loop order in QED
The running of the effective electromagnetic coupling is for many electroweak
observables the dominant correction. It plays an important role for deriving
constraints on the Standard Model in the context of electroweak precision
measurements. We compute the four-loop QED corrections to the running of the
effective electromagnetic coupling and perform a numerical evaluation of the
different gauge invariant subsets.Comment: 26 pages, 4 figure
Higher order QCD results for the fermionic contributions of the Higgs-boson decay into two photons and the decoupling function for the MSbar renormalized fine-structure constant
We compute the decoupling function of the MSbar renormalized fine-structure
constant up to four-loop order in perturbative QCD. The results are used in
order to determine the related top-quark contributions to the Higgs-boson decay
into two photons in the heavy top-quark mass limit to order alpha_s^4.Comment: 19 pages, 4 figure
Shape optimisation for a class of semilinear variational inequalities with applications to damage models
The present contribution investigates shape optimisation problems for a class
of semilinear elliptic variational inequalities with Neumann boundary
conditions. Sensitivity estimates and material derivatives are firstly derived
in an abstract operator setting where the operators are defined on polyhedral
subsets of reflexive Banach spaces. The results are then refined for
variational inequalities arising from minimisation problems for certain convex
energy functionals considered over upper obstacle sets in . One
particularity is that we allow for dynamic obstacle functions which may arise
from another optimisation problems. We prove a strong convergence property for
the material derivative and establish state-shape derivatives under regularity
assumptions. Finally, as a concrete application from continuum mechanics, we
show how the dynamic obstacle case can be used to treat shape optimisation
problems for time-discretised brittle damage models for elastic solids. We
derive a necessary optimality system for optimal shapes whose state variables
approximate desired damage patterns and/or displacement fields
Electroweak corrections in the 2HDM for neutral scalar Higgs-boson production through gluon fusion
We have computed the two-loop, electroweak corrections to the production of a
light and a heavy neutral, scalar Higgs-boson through the important gluon
fusion process in the Two-Higgs-Doublet Model. We provide our results in
various renormalization schemes for different scenarios and benchmark points,
which will be valuable for experimental studies at the LHC. We describe the
technicalities of our two-loop calculation and augment it by a phenomenological
discussion. Our results are also applicable to the gluonic neutral, scalar
Higgs-boson decays.Comment: 36 pages, 11 figures, 8 tables, v2: version accepted for publication
in the journa
Privacy Invasion Experiences and Perceptions: a Comparison Between Germany and the Arab World
Similar to research in behavioral psychology, research in privacy and usable security has focused mainly on Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies. This excludes a large portion of the population affected by privacy implications of technology. In this work, we report on a survey (N=117) in which we studied technology-related privacy concerns of users from different countries, including developing countries such as Egypt, and Saudi Arabia, and developed countries such as Germany. By comparing results from those countries, and relating our findings to previous work, we brought forth multiple novel insights that are specific to privacy of users from under-investigated countries. We discuss the implications of our findings on the design of privacy protection mechanisms
Effective field theory approach to the gravitational two-body dynamics, at fourth post-Newtonian order and quintic in the Newton constant
Working within the post-Newtonian (PN) approximation to General Relativity,
we use the effective field theory (EFT) framework to study the conservative
dynamics of the two-body motion at fourth PN order, at fifth order in the
Newton constant. This is one of the missing pieces preventing the computation
of the full Lagrangian at fourth PN order using EFT methods. We exploit the
analogy between diagrams in the EFT gravitational theory and 2-point functions
in massless gauge theory, to address the calculation of 4-loop amplitudes by
means of standard multi-loop diagrammatic techniques. For those terms which can
be directly compared, our result confirms the findings of previous studies,
performed using different methods.Comment: Version accepted for publication in Phys. Rev. D. Appendix C added
with details of amplitude computation
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