2,011 research outputs found
Lectures on Mirror Symmetry
We give an introduction to mirror symmetry of strings on Calabi-Yau manifolds
with an emphasis on its applications e.g. for the computation of Yukawa
couplings. We introduce all necessary concepts and tools such as the basics of
toric geometry, resolution of singularities, construction of mirror pairs,
Picard-Fuchs equations, etc. and illustrate all of this on a non-trivial
example. Extended version of a lecture given at the Third Baltic Student
Seminar, Helsinki September 1993Comment: LMU-TPW-94-02, 45 pages, harvma
Topological String Partition Functions as Polynomials
We investigate the structure of the higher genus topological string
amplitudes on the quintic hypersurface. It is shown that the partition
functions of the higher genus than one can be expressed as polynomials of five
generators. We also compute the explicit polynomial forms of the partition
functions for genus 2, 3, and 4. Moreover, some coefficients are written down
for all genus.Comment: 22 pages, 6 figures. v2:typos correcte
Mirror Symmetry, Mirror Map and Applications to Complete Intersection Calabi-Yau Spaces
We extend the discussion of mirror symmetry, Picard-Fuchs equations,
instanton-corrected Yukawa couplings, and the topological one-loop partition
function to the case of complete intersections with higher-dimensional moduli
spaces. We will develop a new method of obtaining the instanton-corrected
Yukawa couplings through a close study of the solutions of the Picard-Fuchs
equations. This leads to closed formulas for the prepotential for the K\"ahler
moduli fields induced from the ambient space for all complete intersections in
non singular weighted projective spaces. As examples we treat part of the
moduli space of the phenomenologically interesting three-generation models that
are found in this class. We also apply our method to solve the simplest model
in which a topology change was observed and discuss examples of complete
intersections in singular ambient spaces.Comment: 50 page
Experimental evidence of enhancement without the influence of spin fluctuations: NMR study on LaFeAsO_{1-x}H_x under a pressure of 3.0 GPa
The electron-doped high-transition-temperature (T_c) iron-based pnictide
superconductor LaFeAsO_{1-x}H_x has a unique phase diagram: superconducting
(SC) double domes are sandwiched by antiferromagnetic phases at ambient
pressure and they turn to a single dome with a maximum T_c that exceeds 45K at
a pressure of 3.0 GPa. We studied whether spin fluctuations are involved in
increasing T_c under a pressure of 3.0 GPa by using ^{75}As nuclear magnetic
resonance (NMR) technique. The ^{75}As-NMR results for the powder samples show
that T_c increases up to 48 K without the influence of spin fluctuations. The
fact indicates that spin fluctuations are not involved in raising T_c, which
implies that other factors, such as orbital degrees of freedom, may be
important for achieving a high T_c of almost 50 K.Comment: Correponding Author: Naoki Fujiwar
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