We discuss some aspects of perturbative (0, 2) Calabi-Yau moduli space. In particular, we show how models with different (0, 2) data can meet along various sub-loci in their moduli space. In the simplest examples, the models differ by the choice of desingularization of a holomorphic V-bundle over the same resolved Calabi-Yau base while in more complicated examples, even the smooth Calabi-Yau ba...

Zhongyu Li a,b, Xin Huang a, Song Xu c, Zihui Chen a, Zhi Zhang a, Fushi Zhang a,∗, Kazuo Kasatani d,∗ a Department of Chemistry, Tsinghua University, Beijing 100084, PR China b Department of Chemical Engineering, Jilin Institute of Chemical Technology, Jilin 132022, PR China c Department of Application Technology, Northeast China University of Electric Power Engineering, Jilin 132021, PR China...

We present a determination of the pion-nucleon (πN) σ term σ_{πN} based on the Cheng-Dashen low-energy theorem (LET), taking advantage of the recent high-precision data from pionic atoms to pin down the πN scattering lengths as well as of constraints from analyticity, unitarity, and crossing symmetry in the form of Roy-Steiner equations to perform the extrapolation to the Cheng-Dashen point in ...

The taxonomy of the Afrotropical and Malagasy Paraparatrechina fauna is revised for the first time. Thirteen species are revealed, of which eight are described as new: P. brunnella LaPolla & Cheng; P. concinnata LaPolla & Cheng; P. gnoma LaPolla & Cheng; P. myops LaPolla & Fisher; P. ocellatula LaPolla & Fisher; P. oreias LaPolla & Cheng; P. splendida LaPolla & Cheng; P. umbranatis LaPolla & Ch...

It is argued that black hole condensation can occur at conifold singularities in the moduli space of type II Calabi–Yau string vacua. The condensate signals a smooth transition to a new Calabi–Yau space with different Euler characteristic and Hodge numbers. In this manner string theory unifies the moduli spaces of many or possibly all Calabi–Yau vacua. Elementary string states and black holes a...

The conjectural equivalence of curve counting on Calabi-Yau 3-folds via stable maps and stable pairs is discussed. By considering Calabi-Yau 3-folds with K3 fibrations, the correspondence naturally connects curve and sheaf counting on K3 surfaces. New results and conjectures (with D. Maulik) about descendent integration on K3 surfaces are announced. The recent proof of the Yau-Zaslow conjecture...

The method of gradient estimation for the heat-type equation using Harnack quantity is a classical approach used understanding nature solution these equations. Most studies in this field involve Laplace–Beltrami operator, but our case, we studied weighted heat that involves Laplacian. This produces number terms involving weight function. Thus, article, derive estimate positive nonlinear parabol...

In the text below we try to introduce the concept of a Calabi–Yau manifold. We start by defining vector bundles and complex manifolds, then introduce Kähler manifolds, review the most rudimentary concepts of Chern classes and then define Calabi–Yau manifolds. We also comment on the importance of Calabi–Yau manifolds in physics. As an example to guide us on the way, we have chosen the two-sphere...

In this note we explicitly work out the precise relationship between Ext groups and massless modes of D-branes wrapped on complex submanifolds of Calabi-Yau manifolds. Specifically, we explicitly compute the boundary vertex operators for massless Ramond sector states, in open string B models describing Calabi-Yau manifolds at large radius, directly in BCFT using standard methods. Naively these ...