7,946 research outputs found
Statistical Understanding of Quark and Lepton Masses in Gaussian Landscapes
The fundamental theory of nature may allow a large landscape of vacua. Even
if the theory contains a unified gauge symmetry, the 22 flavor parameters of
the Standard Model, including neutrino masses, may be largely determined by the
statistics of this landscape, and not by any symmetry. Then the measured values
of the flavor parameters do not lead to any fundamental symmetries, but are
statistical accidents; their precise values do not provide any insights into
the fundamental theory, rather the overall pattern of flavor reflects the
underlying landscape. We investigate whether random selection from the
statistics of a simple landscape can explain the broad patterns of quark,
charged lepton, and neutrino masses and mixings. We propose Gaussian landscapes
as simplified models of landscapes where Yukawa couplings result from overlap
integrals of zero-mode wavefunctions in higher-dimensional supersymmetric gauge
theories. In terms of just five free parameters, such landscapes can account
for all gross features of flavor, including: the hierarchy of quark and charged
lepton masses; small quark mixing angles, with 13 mixing less than 12 and 23
mixing; very light Majorana neutrino masses, with the solar to atmospheric
neutrino mass ratio consistent with data; distributions for leptonic 12 and 23
mixings that are peaked at large values, while the distribution for 13 mixing
is peaked at low values; and order unity CP violating phases in both the quark
and lepton sectors. While the statistical distributions for flavor parameters
are broad, the distributions are robust to changes in the geometry of the extra
dimensions. Constraining the distributions by loose cuts about observed values
leads to narrower distributions for neutrino measurements of 13 mixing, CP
violation, and neutrinoless double beta decay.Comment: 86 pages, 26 figures, 2 tables, and table of content
Fast complexified quaternion Fourier transform
A discrete complexified quaternion Fourier transform is introduced. This is a
generalization of the discrete quaternion Fourier transform to the case where
either or both of the signal/image and the transform kernel are complex
quaternion-valued. It is shown how to compute the transform using four standard
complex Fourier transforms and the properties of the transform are briefly
discussed
Quark and Lepton Masses from Gaussian Landscapes
The flavor structure of the standard model (SM) might arise from random selection on a landscape. We propose a class of simple models, “Gaussian landscapes,” where Yukawa couplings derive from overlap integrals of Gaussian wave functions on extra-dimensions. Statistics of vacua are generated by scanning the peak positions of these zero-modes, giving probability distributions for all flavor observables. Gaussian landscapes can account for all observed flavor patterns with few free parameters. Although they give broad probability distributions, the predictions are correlated and accounting for measured parameters sharpens the distributions of future neutrino measurements
Neutrino mixing and mass hierarchy in Gaussian landscapes
The flavor structure of the Standard Model may arise from random selection on
a landscape. In a class of simple models, called "Gaussian landscapes," Yukawa
couplings derive from overlap integrals of Gaussian zero-mode wavefunctions on
an extra-dimensional space. Statistics of vacua are generated by scanning the
peak positions of these wavefunctions, giving probability distributions for all
flavor observables. Gaussian landscapes can account for all of the major
features of flavor, including both the small electroweak mixing in the quark
sector and the large mixing observed in the lepton sector. We find that large
lepton mixing stems directly from lepton doublets having broad wavefunctions on
the internal manifold. Assuming the seesaw mechanism, we find the mass
hierarchy among neutrinos is sensitive to the number of right-handed neutrinos,
and can provide a good fit to neutrino oscillation measurements.Comment: 11 pages, 2 figure
Experimental observation of two-dimensional fluctuation magnetization in the vicinity of T_c for low values of the magnetic field in deoxygenated YBa_2Cu_3O_{7-x}
We measured isofield magnetization curves as a function of temperature in two
single crystal of deoxygenated YBaCuO with T_c = 52 and 41.5 K. Isofield MvsT
were obtained for fields running from 0.05 to 4 kOe. The reversible region of
the magnetization curves was analyzed in terms of a scaling proposed by Prange,
but searching for the best exponent . The scaling analysis carried
out for each data sample set with =0.669, which corresponds to the
3D-xy exponent, did not produced a collapsing of curves when applied to MvsT
curves data obtained for the lowest fields. The resulting analysis for the Y123
crystal with T_c = 41.5 K, shows that lower field curves collapse over the
entire reversible region following the Prange's scaling with =1,
suggesting a two-dimensional behavior. It is shown that the same data obeying
the Prange's scaling with =1 for crystal with T_c = 41.5 K, as well
low field data for crystal with = 52 K, obey the known two-dimensional
scaling law obtained in the lowest-Landau-level approximation.Comment: 4 pages, 3 figure
J. Walter (Hrsg.) (1983): Sexualität und geistige Behinderung. Heidelberg: G. Schindele Verlag (162 Seiten; DM 22,-) [...] [Sammelrezension]
Sammelrezension von J. Walter (Hrsg.) (1983): Sexualität und geistige Behinderung. Heidelberg: G. Schindele Verlag (162 Seiten; DM 22,-); A. Hoyler-Herrmann, J. Walter (Hrsg.) (1983): Sexualpädagogische Arbeitshilfe für geistig behinderte Erwachsene. Heidelberg: G. Schindele Verlag (102 Seiten; DM 17,-
A Robust Solution Procedure for Hyperelastic Solids with Large Boundary Deformation
Compressible Mooney-Rivlin theory has been used to model hyperelastic solids,
such as rubber and porous polymers, and more recently for the modeling of soft
tissues for biomedical tissues, undergoing large elastic deformations. We
propose a solution procedure for Lagrangian finite element discretization of a
static nonlinear compressible Mooney-Rivlin hyperelastic solid. We consider the
case in which the boundary condition is a large prescribed deformation, so that
mesh tangling becomes an obstacle for straightforward algorithms. Our solution
procedure involves a largely geometric procedure to untangle the mesh: solution
of a sequence of linear systems to obtain initial guesses for interior nodal
positions for which no element is inverted. After the mesh is untangled, we
take Newton iterations to converge to a mechanical equilibrium. The Newton
iterations are safeguarded by a line search similar to one used in
optimization. Our computational results indicate that the algorithm is up to 70
times faster than a straightforward Newton continuation procedure and is also
more robust (i.e., able to tolerate much larger deformations). For a few
extremely large deformations, the deformed mesh could only be computed through
the use of an expensive Newton continuation method while using a tight
convergence tolerance and taking very small steps.Comment: Revision of earlier version of paper. Submitted for publication in
Engineering with Computers on 9 September 2010. Accepted for publication on
20 May 2011. Published online 11 June 2011. The final publication is
available at http://www.springerlink.co
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