3,903 research outputs found
Sigma Model BPS Lumps on Torus
We study doubly periodic Bogomol'nyi-Prasad-Sommerfield (BPS) lumps in
supersymmetric CP^{N-1} non-linear sigma models on a torus T^2. Following the
philosophy of the Harrington-Shepard construction of calorons in Yang-Mills
theory, we obtain the n-lump solutions on compact spaces by suitably arranging
the n-lumps on R^2 at equal intervals. We examine the modular invariance of the
solutions and find that there are no modular invariant solutions for n=1,2 in
this construction.Comment: 15 pages, 3 figures, published versio
Tensor-optimized shell model for the Li isotopes with a bare nucleon-nucleon interaction
We study the Li isotopes systematically in terms of the tensor-optimized
shell model (TOSM) by using a bare nucleon-nucleon interaction as the AV8'
interaction. The short-range correlation is treated in the unitary correlation
operator method (UCOM). Using the TOSM+UCOM approach, we investigate the role
of the tensor force on each spectrum of the Li isotopes. It is found that the
tensor force produces quite a characteristic effect on various states in each
spectrum and those spectra are affected considerably by the tensor force. The
energy difference between the spin-orbit partner, the p1/2 and p3/2 orbits of
the last neutron, in 5Li is caused by opposite roles of the tensor correlation.
In 6Li, the spin-triplet state in the LS coupling configuration is favored
energetically by the tensor force in comparison with jj coupling shell model
states. In 7,8,9Li, the low-lying states containing extra neutrons in the p3/2
orbit are favored energetically due to the large tensor contribution to allow
the excitation from the 0s orbit to the p1/2 orbit by the tensor force. Those
three nuclei show the jj coupling character in their ground states which is
different from 6Li.Comment: 12 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1108.393
Weak commutation relations of unbounded operators and applications
Four possible definitions of the commutation relation [S,T]=\Id of two
closable unbounded operators are compared. The {\em weak} sense of this
commutator is given in terms of the inner product of the Hilbert space \H
where the operators act. Some consequences on the existence of eigenvectors of
two number-like operators are derived and the partial O*-algebra generated by
is studied. Some applications are also considered.Comment: In press in Journal of Mathematical Physic
Neutrino masses and mixing from S4 flavor twisting
We discuss a neutrino mass model based on the S4 discrete symmetry where the
symmetry breaking is triggered by the boundary conditions of the bulk
right-handed neutrino in the fifth spacial dimension. While the symmetry
restricts bare mass parameters to flavor-diagonal forms, the viable mixing
angles emerge from the wave functions of the Kaluza-Klein modes which carry
symmetry breaking effect. The magnitudes of the lepton mixing angles,
especially the reactor angle is related to the neutrino mass patterns and the
model will be tested in future neutrino experiments, e.g., an early (late)
discovery of the reactor angle favors the normal (inverted) hierarchy. The size
of extra dimension has a connection to the possible mass spectrum; a small
(large) volume corresponds to the normal (inverted) mass hierarchy.Comment: 22 pages, 3 figures; added references for section
Forecasting the Cosmological Constraints with Anisotropic Baryon Acoustic Oscillations from Multipole Expansion
Baryon acoustic oscillations (BAOs) imprinted in the galaxy power spectrum
can be used as a standard ruler to determine angular diameter distance and
Hubble parameter at high redshift galaxies. Combining redshift distortion
effect which apparently distorts the galaxy clustering pattern, we can also
constrain the growth rate of large-scale structure formation. Usually, future
forecast for constraining these parameters from galaxy redshift surveys has
been made with a full 2D power spectrum characterized as function of wavenumber
and directional cosine between line-of-sight direction and wave
vector, i.e., . Here, we apply the multipole expansion to the full 2D
power spectrum, and discuss how much cosmological information can be extracted
from the lower-multipole spectra, taking a proper account of the non-linear
effects on gravitational clustering and redshift distortion. The Fisher matrix
analysis reveals that compared to the analysis with full 2D spectrum, a partial
information from the monopole and quadrupole spectra generally degrades the
constraints by a factor of for each parameter. The additional
information from the hexadecapole spectrum helps to improve the constraints,
which lead to an almost comparable result expected from the full 2D spectrum.Comment: 12 pages, 6 figure
The development and neural basis of referential gaze perception
Infants are sensitive to the referential information conveyed by others’ eye gaze, which could be one of the developmental foundations of theory of mind. To investigate the neural correlates of gaze–object relations, we recorded ERPs from adults and 9-month-old infants while they watched scenes containing gaze shifts either towards or away from the location of a preceding object. In adults, object-incongruent gaze shifts elicited enhanced ERP amplitudes over the occipito-temporal area (N330). In infants, a similar posterior ERP component (N290) was greater for object-incongruent gaze shifts, which suggests that by the age of 9 months infants encode referential information of gaze in a similar way to adults. In addition, in infants we observed an early frontal ERP component (anterior N200), which showed higher amplitude in response to the perception of object-congruent gaze shifts. This component may reflect fast-track processing of socially relevant information, such as the detection of communicative or informative situations, and could form a developmental foundation for attention sharing, social learning and theory of mind
Live imaging of whole mouse embryos during gastrulation : migration analyses of epiblast and mesodermal cells
During gastrulation in the mouse embryo, dynamic cell movements including epiblast invagination and mesodermal layer expansion lead to the establishment of the three-layered body plan. The precise details of these movements, however, are sometimes elusive, because of the limitations in live imaging. To overcome this problem, we developed techniques to enable observation of living mouse embryos with digital scanned light sheet microscope (DSLM). The achieved deep and high time-resolution images of GFP-expressing nuclei and following 3D tracking analysis revealed the following findings: (i) Interkinetic nuclear migration (INM) occurs in the epiblast at embryonic day (E)6 and 6.5. (ii) INM-like migration occurs in the E5.5 embryo, when the epiblast is a monolayer and not yet pseudostratified. (iii) Primary driving force for INM at E6.5 is not pressure from neighboring nuclei. (iv) Mesodermal cells migrate not as a sheet but as individual cells without coordination
Detecting a stochastic background of gravitational waves in the presence of non-Gaussian noise: A performance of generalized cross-correlation statistic
We discuss a robust data analysis method to detect a stochastic background of
gravitational waves in the presence of non-Gaussian noise. In contrast to the
standard cross-correlation (SCC) statistic frequently used in the stochastic
background searches, we consider a {\it generalized cross-correlation} (GCC)
statistic, which is nearly optimal even in the presence of non-Gaussian noise.
The detection efficiency of the GCC statistic is investigated analytically,
particularly focusing on the statistical relation between the false-alarm and
the false-dismissal probabilities, and the minimum detectable amplitude of
gravitational-wave signals. We derive simple analytic formulae for these
statistical quantities. The robustness of the GCC statistic is clarified based
on these formulae, and one finds that the detection efficiency of the GCC
statistic roughly corresponds to the one of the SCC statistic neglecting the
contribution of non-Gaussian tails. This remarkable property is checked by
performing the Monte Carlo simulations and successful agreement between
analytic and simulation results was found.Comment: 15 pages, 8 figures, presentation and some figures modified, final
version to be published in PR
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