8,362 research outputs found
Emergent Calabi-Yau Geometry
We show how the smooth geometry of Calabi-Yau manifolds emerges from the
thermodynamic limit of the statistical mechanical model of crystal melting
defined in our previous paper arXiv:0811.2801. In particular, the thermodynamic
partition function of molten crystals is shown to be equal to the classical
limit of the partition function of the topological string theory by relating
the Ronkin function of the characteristic polynomial of the crystal melting
model to the holomorphic 3-form on the corresponding Calabi-Yau manifold.Comment: 4 pages; v2: revised discussion on wall crossing; v3: typos
corrected, published versio
Virtual light-by-light scattering and the g factor of a bound electron
The contribution of the light-by-light diagram to the g factor of electron
and muon bound in Coulomb field is obtained. For electron in a ground state,
our results are in good agreement with the results of other authors obtained
numerically for large Z. For relatively small Z our results have essentially
higher accuracy as compared to the previous ones. For muonic atoms, the
contribution is obtained for the first time with the high accuracy in whole
region of Z.Comment: 10 pages, 3 figures, RevTe
Direct Observation of the Hyperfine Transition of the Ground State Positronium
We report the first direct measurement of the hyperfine transition of the
ground state positronium. The hyperfine structure between ortho-positronium and
para-positronium is about 203 GHz. We develop a new optical system to
accumulate about 10 kW power using a gyrotron, a mode converter, and a
Fabry-P\'{e}rot cavity. The hyperfine transition has been observed with a
significance of 5.4 standard deviations. The transition probability is measured
to be s for the first time, which
is in good agreement with the theoretical value of
s
Collective patterns arising out of spatio-temporal chaos
We present a simple mathematical model in which a time averaged pattern
emerges out of spatio-temporal chaos as a result of the collective action of
chaotic fluctuations. Our evolution equation possesses spatial translational
symmetry under a periodic boundary condition. Thus the spatial inhomogeneity of
the statistical state arises through a spontaneous symmetry breaking. The
transition from a state of homogeneous spatio-temporal chaos to one exhibiting
spatial order is explained by introducing a collective viscosity which relates
the averaged pattern with a correlation of the fluctuations.Comment: 11 pages (Revtex) + 5 figures (postscript
I=2 Pion Scattering Length from Two-Pion Wave Functions
We calculate the two-pion wave function in the ground state of the I=2
-wave system and find the interaction range between two pions, which allows
us to examine the validity of the necessary condition for the finite-volume
method for the scattering length proposed by L\"uscher. We work in the quenched
approximation employing a renormalization group improved gauge action for
gluons and an improved Wilson action for quarks at on
, and lattices. We conclude
that the necessary condition is satisfied within the statistical errors for the
lattice sizes () when the quark mass is in the range
that corresponds to . We obtain the
scattering length with a smaller statistical error from the wave function than
from the two-pion time correlator.Comment: LaTeX2e, 34 pages, 11 eps figures, uses revtex4 and graphic
A Note on Dimer Models and D-brane Gauge Theories
The connection between quiver gauge theories and dimer models has been well
studied. It is known that the matter fields of the quiver gauge theories can be
represented using the perfect matchings of the corresponding dimer model.We
conjecture that a subset of perfect matchings associated with an internal point
in the toric diagram is sufficient to give information about the charge matrix
of the quiver gauge theory. Further, we perform explicit computations on some
aspects of partial resolutions of toric singularities using dimer models. We
analyse these with graph theory techniques, using the perfect matchings of
orbifolds of the form \BC^3/\Gamma, where the orbifolding group may
be noncyclic. Using these, we study the construction of the superpotential of
gauge theories living on D-branes which probe these singularities, including
the case where one or more adjoint fields are present upon partial resolution.
Applying a combination of open and closed string techniques to dimer models, we
also study some aspects of their symmetries.Comment: Discussions expanded, clarifications added, typos fixed. 1+49 page
g-factor of a tightly bound electron
We study the hyperfine splitting of an electron in hydrogen-like . It is found that the hfs energy splitting can be explained well by
considering the g-factor reduction due to the binding effect of a bound
electron. We determine for the first time the experimental value of the
magnetic moment of a tightly bound electron.Comment: 6 pages, Latex, Phys. Rev. A in pres
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