2,587 research outputs found
Bosonic String and String Field Theory: a solution using Ultradistributions of Exponential Type
In this paper we show that Ultradistributions of Exponential Type (UET) are
appropriate for the description in a consistent way string and string field
theories. A new Lagrangian for the closed string is obtained and shown to be
equivalent to Nambu-Goto's Lagrangian. We also show that the string field is a
linear superposition of UET of compact support CUET). We evaluate the
propagator for the string field, and calculate the convolution of two of them.Comment: 30 page
Convolution of n-dimensional Tempered Ultradistributions and Field Theory
In this work, a general definition of convolution between two arbitrary
Tempered Ultradistributions is given. When one of the Tempered
Ultradistributions is rapidly decreasing this definition coincides with the
definition of J. Sebastiao e Silva. In the four-dimensional case, when the
Tempered Ultradistributions are even in the variables and (see
Section 5) we obtain an expression for the convolution, which is more suitable
for practical applications. The product of two arbitrary even (in the variables
and ) four dimensional distributions of exponential type is defined
via the convolution of its corresponding Fourier Transforms. With this
definition of convolution, we treat the problem of singular products of Green
Functions in Quantum Field Theory. (For Renormalizable as well as for
Nonrenormalizable Theories). Several examples of convolution of two Tempered
Ultradistributions are given. In particular we calculate the convolution of two
massless Wheeeler's propagators and the convolution of two complex mass
Wheeler's propagators.Comment: 28 page
Interfaces of the Agriculture 4.0
The introduction of information technologies in the environmental field is impacting and changing even a traditional sector like agriculture. Nevertheless, Agriculture 4.0 and data-driven decisions should meet user
needs and expectations. The paper presents a broad theoretical overview, discussing both the strategic role of design applied to Agri-tech and the issue of User Interface and Interaction as enabling tools in the field. In
particular, the paper suggests to rethink the HCD approach, moving on a Human-Decentered Design approach that put together user-technology-environment and the importance of the role of calm technologies as a way
to place the farmer, not as a final target and passive spectator, but as an active part of the process to aim the process of mitigation, appropriation from a traditional cultivation method to the 4.0 one
Convolution of Lorentz Invariant Ultradistributions and Field Theory
In this work, a general definition of convolution between two arbitrary four
dimensional Lorentz invariant (fdLi) Tempered Ultradistributions is given, in
both: Minkowskian and Euclidean Space (Spherically symmetric tempered
ultradistributions). The product of two arbitrary fdLi distributions of
exponential type is defined via the convolution of its corresponding Fourier
Transforms. Several examples of convolution of two fdLi Tempered
Ultradistributions are given. In particular we calculate exactly the
convolution of two Feynman's massless propagators. An expression for the
Fourier Transform of a Lorentz invariant Tempered Ultradistribution in terms of
modified Bessel distributions is obtained in this work (Generalization of
Bochner's formula to Minkowskian space). At the same time, and in a previous
step used for the deduction of the convolution formula, we obtain the
generalization to the Minkowskian space, of the dimensional regularization of
the perturbation theory of Green Functions in the Euclidean configuration space
given in ref.[12]. As an example we evaluate the convolution of two
n-dimensional complex-mass Wheeler's propagators.Comment: LaTeX, 52 pages, no figure
A Family of unitary higher order equations
A scalar field obeying a Lorentz invariant higher order wave equation, is
minimally coupled to the electromagnetic field. The propagator and vertex
factors for the Feynman diagrams, are determined. As an example we write down
the matrix element for the Compton effect. This matrix element is algebraically
reduced to the usual one for a charged Klein-Gordon particle. It is proved that
the order theory is equivalent to n independent second order
theories. It is also shown that the higher order theory is both renormalizable
and unitary for arbitrary n.Comment: 17 pages, LaTex, no figure
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