3,444 research outputs found
Constraints on Neutrino Parameters from Neutral-Current Solar Neutrino Measurements
We generalize the pull approach to define the function to the
analysis of the data with correlated statistical errors. We apply this method
to the analysis of the Sudbury Neutrino Collaboration data obtained in the
salt-phase. In the global analysis of all the solar neutrino and KamLAND data
we find the best fit (minimum ) values of neutrino parameters to be
and
eV. We confirm that the maximal mixing is strongly disfavored while the
bounds on are significantly strengthened.Comment: 6 figures. Some typos are corrected, figures are visually improve
On the Crepant Resolution Conjecture in the Local Case
In this paper we analyze four examples of birational transformations between
local Calabi-Yau 3-folds: two crepant resolutions, a crepant partial
resolution, and a flop. We study the effect of these transformations on
genus-zero Gromov-Witten invariants, proving the
Coates-Corti-Iritani-Tseng/Ruan form of the Crepant Resolution Conjecture in
each case. Our results suggest that this form of the Crepant Resolution
Conjecture may also hold for more general crepant birational transformations.
They also suggest that Ruan's original Crepant Resolution Conjecture should be
modified, by including appropriate "quantum corrections", and that there is no
straightforward generalization of either Ruan's original Conjecture or the
Cohomological Crepant Resolution Conjecture to the case of crepant partial
resolutions. Our methods are based on mirror symmetry for toric orbifolds.Comment: 27 pages. This is a substantially revised and shortened version of my
preprint "Wall-Crossings in Toric Gromov-Witten Theory II: Local Examples";
all results contained here are also proved there. To appear in Communications
in Mathematical Physic
mRNA transfection of mouse and human neural stem cell cultures
The use of synthetic mRNA as an alternative gene delivery vector to traditional DNA-based constructs provides an effective method for inducing transient gene expression in cell cultures without genetic modification. Delivery of mRNA has been proposed as a safer alternative to viral vectors in the induction of pluripotent cells for regenerative therapies. Although mRNA transfection of fibroblasts, dendritic and embryonic stem cells has been described, mRNA delivery to neurosphere cultures has not been previously reported. Here we sought to establish an efficient method for delivering mRNA to primary neurosphere cultures. Neurospheres derived from the subventricular zone of adult mice or from human embryonic stem cells were transfected with EGFP mRNA by lipofection and electroporation. Transfection efficiency and expression levels were monitored by flow cytometry. Cell survival following transfection was examined using live cell counting and the MTT assay. Both lipofection and electroporation provided high efficiency transfection of neurospheres. In comparison with lipofection, electroporation resulted in increased transfection efficiencies, but lower expression per cell and shorter durations of expression. Additional rounds of lipofection renewed EGFP expression in neurospheres, suggesting this method may be suitable for reprogramming applications. In summary, we have developed a protocol for achieving high efficiency transfection rates in mouse and human neurosphere cell culture that can be applied for future studies of gene function studies in neural stem cells, such as defining efficient differentiation protocols for glial and neuronal linages
Bi-local baryon interpolating fields with two flavours
We construct bi-local interpolating field operators for baryons consisting of
three quarks with two flavors, assuming good isospin symmetry. We use the
restrictions following from the Pauli principle to derive relations/identities
among the baryon operators with identical quantum numbers. Such relations that
follow from the combined spatial, Dirac, color, and isospin Fierz
transformations may be called the (total/complete) Fierz identities. These
relations reduce the number of independent baryon operators with any given spin
and isospin. We also study the Abelian and non-Abelian chiral transformation
properties of these fields and place them into baryon chiral multiplets. Thus
we derive the independent baryon interpolating fields with given values of spin
(Lorentz group representation), chiral symmetry ( group
representation) and isospin appropriate for the first angular excited states of
the nucleon.Comment: 15 pages, 4 tables, accepted by EPJ
Glueball plus Pion Production in Photon-Photon Collisions.
We here compute the reaction
for various glueball candidates and their assumed quantum states, using a
non-relativistic gluon bound-state model for the glueball.Comment: To appear in Zeit. fur Phys. C; Plain Latex file, 16 pages; 5 figures
appended as a uuencoded postscript file
Deconfined criticality, runaway flow in the two-component scalar electrodynamics and weak first-order superfluid-solid transitions
We perform a comparative Monte Carlo study of the easy-plane deconfined
critical point (DCP) action and its short-range counterpart to reveal close
similarities between the two models for intermediate and strong coupling
regimes. For weak coupling, the structure of the phase diagram depends on the
interaction range: while the short-range model features a tricritical point and
a continuous U(1)xU(1) transition,the long-range DCP action is characterized by
the runaway renormalization flow of coupling into a first (I) order phase
transition. We develop a "numerical flowgram" method for high precision studies
of the runaway effect, weakly I-order transitions, and polycritical points. We
prove that the easy-plane DCP action is the field theory of a weakly I-order
phase transition between the valence bond solid and the easy-plane
antiferromagnet (or superfluid, in particle language) for any value of the weak
coupling strength. Our analysis also solves the long standing problem of what
is the ultimate fate of the runaway flow to strong coupling in the theory of
scalar electrodynamics in three dimensions with U(1)xU(1) symmetry of quartic
interactionsComment: 25 pages, 18 figures, Mottness and quantum criticality conference (to
appear in Annals of physics
Crossover and scaling in a two-dimensional field-tuned superconductor
Using an analysis similar to that of Imry and Wortis, it is shown that the
apparent first order superconductor to metal transition, which has been claimed
to exist at low values of the magnetic field in a two-dimensional field-tuned
system at zero temperature,can be consistentlyinterpreted as a sharp crossover
from a strong superconductor to an inhomogeneous state, which is a weak
superconductor. The true zero-temperature superconductor to insulator
transition within the inhomogenous state is conjectured to be that of randomly
diluted XY model. An explaination of the observed finite temperature
approximate scaling of resistivity close to the critical point is speculated
within this model.Comment: 5 pages, 2 figures, corrected and modified according to referee
Report
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