8,245 research outputs found
Invitation to composition
In 1963 [Ann. of Math. {\bf 78}, 267-288], Gerstenhaber invented a
\emph{comp(osition)} calculus in the Hochschild complex of an associative
algebra. In this paper, the first steps of the Gerstenhaber theory are exposed
in an abstract (comp system) setting. In particular, as in the Hochschild
complex, a graded Lie algebra and a pre-coboundary operator can be associated
to every comp system. A derivation deviation of the pre-coboundary operator
over the total composition is calculated in two ways, (the long) one of which
is essentially new and can be seen as an example and elaboration of the
auxiliary variables method proposed by Gerstenhaber in the early days of the
comp calculus.Comment: 18 pages, AMSLaTe
Light Colored Scalar as Messenger of Up-Quark Flavor Dynamics in Grand Unified Theories
The measured forward-backward asymmetry in the t tbar production at the
Tevatron might be explained by the additional exchange of a colored weak
singlet scalar. Such state appears in some of the grand unified theories and
its interactions with the up-quarks are purely antisymmetric in flavor space.
We systematically investigate the resulting impact on charm and top quark
physics. The constraints on the relevant Yukawa couplings come from the
experimentally measured observables related to D0--D0bar oscillations, as well
as di-jet and single top production measurements at the Tevatron. After fully
constraining the relevant Yukawa couplings, we predict possible signatures of
this model in rare top quark decays. In a class of grand unified models we
demonstrate how the obtained information enables to constrain the Yukawa
couplings of the up-quarks at very high energy scale.Comment: 13 pages, 11 figures, version as published in PR
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