2,639 research outputs found
Electroweak higher-order effects and theoretical uncertainties in deep-inelastic neutrino scattering
A previous calculation of electroweak O(alpha) corrections to deep-inelastic
neutrino scattering, as e.g. measured by NuTeV and NOMAD, is supplemented by
higher-order effects. In detail, we take into account universal two-loop
effects from \Delta\alpha and \Delta\rho as well as higher-order final-state
photon radiation off muons in the structure function approach. Moreover, we
make use of the recently released O(alpha)-improved parton distributions
MRST2004QED and identify the relevant QED factorization scheme, which is DIS
like. As a technical byproduct, we describe slicing and subtraction techniques
for an efficient calculation of a new type of real corrections that are induced
by the generated photon distribution. A numerical discussion of the
higher-order effects suggests that the remaining theoretical uncertainty from
unknown electroweak corrections is dominated by non-universal two-loop effects
and is of the order 0.0003 when translated into a shift in
sin^2\theta_W=1-MW^2/MZ^2. The O(alpha) corrections implicitly included in the
parton distributions lead to a shift of about 0.0004.Comment: 25 pages, latex, 8 postscript figure
In Quest for Proper Mediums for Technology Transfer in Software Engineering
Successful transfer of the results of research projects into practice is of
great interest to all project participants. It can be assumed that different
transfer mediums fulfill technology transfer (TT) with different levels of
success and that they are impaired by different kinds of barriers. The goal of
this study is to gain a better understanding about the different mediums used
for TT in software engineering, and to identify barriers weakening the success
of the application of such mediums. We conducted an exploratory study
implemented by a survey in the context of a German research project with a
broad range of used mediums. The main reported barriers were low expectations
of usefulness, no awareness of existence, lack of resources, or inadequateness
in terms of outdated material or being in an immature state. We interpreted our
results as symptoms of a lack of a dissemination plan in the project. Further
work will be needed to explore the implications for the transfer of research
results (knowledge and techniques) to practice.Comment: Proceedings of the International Conference on Empirical Software
Engineering and Measurement, 201
Weyl-van-der-Waerden formalism for helicity amplitudes of massive particles
The Weyl-van-der-Waerden spinor technique for calculating helicity amplitudes
of massive and massless particles is presented in a form that is particularly
well suited to a direct implementation in computer algebra. Moreover, we
explain how to exploit discrete symmetries and how to avoid unphysical poles in
amplitudes in practice. The efficiency of the formalism is demonstrated by
giving explicit compact results for the helicity amplitudes of the processes
gamma gamma -> f fbar, f fbar -> gamma gamma gamma, mu^- mu^+ -> f fbar gamma.Comment: 24 pages, late
Morita base change in Hopf-cyclic (co)homology
In this paper, we establish the invariance of cyclic (co)homology of left
Hopf algebroids under the change of Morita equivalent base algebras. The
classical result on Morita invariance for cyclic homology of associative
algebras appears as a special example of this theory. In our main application
we consider the Morita equivalence between the algebra of complex-valued smooth
functions on the classical 2-torus and the coordinate algebra of the
noncommutative 2-torus with rational parameter. We then construct a Morita base
change left Hopf algebroid over this noncommutative 2-torus and show that its
cyclic (co)homology can be computed by means of the homology of the Lie
algebroid of vector fields on the classical 2-torus.Comment: Final version to appear in Lett. Math. Phy
The role of electromagnetic trapped modes in extraordinary transmission in nanostructured materials
We assert that the physics underlying the extraordinary light transmission
(reflection) in nanostructured materials can be understood from rather general
principles based on the formal scattering theory developed in quantum
mechanics. The Maxwell equations in passive (dispersive and absorptive) linear
media are written in the form of the Schr\"{o}dinger equation to which the
quantum mechanical resonant scattering theory (the Lippmann-Schwinger
formalism) is applied. It is demonstrated that the existence of long-lived
quasistationary eigenstates of the effective Hamiltonian for the Maxwell theory
naturally explains the extraordinary transmission properties observed in
various nanostructured materials. Such states correspond to quasistationary
electromagnetic modes trapped in the scattering structure. Our general approach
is also illustrated with an example of the zero-order transmission of the
TE-polarized light through a metal-dielectric grating structure. Here a direct
on-the-grid solution of the time-dependent Maxwell equations demonstrates the
significance of resonances (or trapped modes) for extraordinary light
transmissioComment: 14 pages, 6 figures; Discussion in Section 4 expanded; typos
corrected; a reference added; Figure 4 revise
Higgs coupling constants as a probe of new physics
We study new physics effects on the couplings of weak gauge bosons with the
lightest CP-even Higgs boson (), , and the tri-linear coupling of the
lightest Higgs boson, , at the one loop order, as predicted by the two
Higgs doublet model. Those renormalized coupling constants can deviate from the
Standard Model (SM) predictions due to two distinct origins; the tree level
mixing effect of Higgs bosons and the quantum effect of additional particles in
loop diagrams. The latter can be enhanced in the renormalized coupling
constant when the additional particles show the non-decoupling property.
Therefore, even in the case where the coupling is close to the SM value,
deviation in the coupling from the SM value can become as large as plus
100 percent, while that in the coupling is at most minus 1 percent level.
Such large quantum effect on the Higgs tri-linear coupling is distinguishable
from the tree level mixing effect, and is expected to be detectable at a future
linear collider.Comment: 52 pages, 10 figures, revtex
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