5,491 research outputs found
Lower Mass Bound on the mass via Neutrinoless Double Beta Decay in a 3-3-1 Model
The discovery of neutrino masses has raised the importance of studies in the
context of neutrinoless double beta decay, which constitutes a landmark for
lepton number violation. The standard interpretation is that the light massive
neutrinos, that we observed oscillating in terrestrial experiments, mediate
double beta decay. In the minimal 3-3-1 model, object of our study, there is an
additional contribution that stems from the mixing between a new charged vector
boson, , and the Standard Model W boson. Even after setting this
mixing to be very small, we show that tight constraints arise from the
non-observation of neutrinoless double beta decay. Indeed, we derive bounds on
the mass of the gauge boson that might exceed those from collider
probes, and most importantly push the scale of symmetry breaking beyond its
validity, leading to the exclusion of the minimal 3-3-1 model.Comment: 16 pages, 5 figure
Interface growth in two dimensions: A Loewner-equation approach
The problem of Laplacian growth in two dimensions is considered within the
Loewner-equation framework. Initially the problem of fingered growth recently
discussed by Gubiec and Szymczak [T. Gubiec and P. Szymczak, Phys. Rev. E 77,
041602 (2008)] is revisited and a new exact solution for a three-finger
configuration is reported. Then a general class of growth models for an
interface growing in the upper-half plane is introduced and the corresponding
Loewner equation for the problem is derived. Several examples are given
including interfaces with one or more tips as well as multiple growing
interfaces. A generalization of our interface growth model in terms of
``Loewner domains,'' where the growth rule is specified by a time evolving
measure, is briefly discussed.Comment: To appear in Physical Review
Promoting safety during process variability : a multidisciplinary challenge
Variability can be defined as the inherent instability of any type of process. In manufacturing
settings, some efforts in reducing process variability have been developed, but zero variability
seems to be, so far, an infeasible target. Ergonomic studies have been showing that workers are usually
the ones responsible for residual variability. However, it can have impact over the safety of workers. The
main purpose of this paper is to demonstrate that the need for managing residual variability in addition
to putting the workers in a position of transgressors, it also exposes them to unforeseen risks. To achieve
that, three examples of variability situations are described. The main method applied was the Ergonomic
Analysis of Work Activity. It is argued that there is the need for a multidisciplinary approach, including
not only OH&S professionals, but also human resources and engineering designers, to promote safety
during process variability.This work was partially supported by a grant from the Brazilian National Council for Scientific and Technological Development ( CNPq / Brazil)
Exponential Distributions in a Mechanical Model for Earthquakes
We study statistical distributions in a mechanical model for an earthquake
fault introduced by Burridge and Knopoff [R. Burridge and L. Knopoff, {\sl
Bull. Seismol. Soc. Am.} {\bf 57}, 341 (1967)]. Our investigations on the size
(moment), time duration and number of blocks involved in an event show that
exponential distributions are found in a given range of the paramenter space.
This occurs when the two kinds of springs present in the model have the same,
or approximately the same, value for the elastic constants. Exponential
distributions have also been seen recently in an experimental system to model
earthquake-like dynamics [M. A. Rubio and J. Galeano, {\sl Phys. Rev. E} {\bf
50}, 1000 (1994)].Comment: 11 pages, uuencoded (submitted to Phys. Rev. E
Mucinous cystadenoma of the appendix
A cystic mass in the right iliac fossa of an asymptomatic patient
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