10,215 research outputs found
2D-Oide effect
The Oide effect considers the synchrotron radiation in the final focusing
quadrupole and it sets a lower limit on the vertical beam size at the
Interaction Point, particularly relevant for high energy linear colliders. The
theory of the Oide effect was derived considering only the radiation in the
focusing plane of the magnet. This article addresses the theoretical
calculation of the radiation effect on the beam size consider- ing both
focusing and defocusing planes of the quadrupole, refered to as 2D-Oide. The
CLIC 3 TeV final quadrupole (QD0) and beam parameters are used to compare the
theoretical results from the Oide effect and the 2D-Oide effect with particle
tracking in PLACET. The 2D-oide demonstrates to be important as it increases by
17% the contribution to the beam size. Further insight into the aberrations
induced by the synchrotron radiation opens the possibility to partially correct
the 2D-Oide effect with octupole mag
Parabolic bundles and representations of the fundamental group
Let X be as smooth complex projective variety with Neron-Severi group
isomorphic to Z, and D an irreducible divisor with normal crossing
singularities. Assume r is equal to 2 or 3. We prove that if the fundamental
group of X doesn't have irreducible PU(r) representations, then the fundamental
group of X-D doesn't have irreducible U(r) representations. The proof uses the
non-existence of certain stable parabolic bundles. We also obtain a similar
result for GL(2) when D is smooth and X is a complex surface.Comment: 13 pages, 1 figure, LaTeX2
Calculation of nuclear matrix elements in neutrinoless double electron capture
We compute nuclear matrix elements for neutrinoless double electron capture
on Gd, Er and W nuclei. Recent precise mass
measurements for these nuclei have shown a large resonance enhancement factor
that makes them the most promising candidates for observing this decay mode. We
use an advanced energy density functional method which includes beyond
mean-field effects such as symmetry restoration and shape mixing. Our
calculations reproduce experimental charge radii and values predicting
a large deformation for all these nuclei. This fact reduces significantly the
values of the NMEs leading to half-lives larger than years for the
three candidates
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