263 research outputs found
Complex Multiplication of Exactly Solvable Calabi-Yau Varieties
We propose a conceptual framework that leads to an abstract characterization
for the exact solvability of Calabi-Yau varieties in terms of abelian varieties
with complex multiplication. The abelian manifolds are derived from the
cohomology of the Calabi-Yau manifold, and the conformal field theoretic
quantities of the underlying string emerge from the number theoretic structure
induced on the varieties by the complex multiplication symmetry. The geometric
structure that provides a conceptual interpretation of the relation between
geometry and the conformal field theory is discrete, and turns out to be given
by the torsion points on the abelian varieties.Comment: 44 page
Conifold Transitions and Mirror Symmetries
Recent work initiated by Strominger has lead to a consistent physical
interpretation of certain types of transitions between different string vacua.
These transitions, discovered several years ago, involve singular conifold
configurations which connect distinct Calabi-Yau manifolds. In this paper we
discuss a number of aspects of conifold transitions pertinent to both
worldsheet and spacetime mirror symmetry. It is shown that the mirror transform
based on fractional transformations allows an extension of the mirror map to
conifold boundary points of the moduli space of weighted Calabi-Yau manifolds.
The conifold points encountered in the mirror context are not amenable to an
analysis via the original splitting constructions. We describe the first
examples of such nonsplitting conifold transitions, which turn out to connect
the known web of Calabi-Yau spaces to new regions of the collective moduli
space. We then generalize the splitting conifold transition to weighted
manifolds and describe a class of connections between the webs of ordinary and
weighted projective Calabi-Yau spaces. Combining these two constructions we
find evidence for a dual analog of conifold transitions in heterotic N2
compactifications on K3T and in particular describe the first
conifold transition of a Calabi-Yau manifold whose heterotic dual has been
identified by Kachru and Vafa. We furthermore present a special type of
conifold transition which, when applied to certain classes of Calabi-Yau K3
fibrations, preserves the fiber structure.Comment: 23 page
Heterotic/Type II Duality in D=4 and String/String Duality
We discuss the structure of heterotic/type II duality in four dimensions as a
consequence of string-string duality in six dimensions. We emphasize the new
features in four dimensions which go beyond the six dimensional vacuum
structure and pertain to the way particular K3 fibers can be embedded in
Calabi-Yau threefolds. Our focus is on hypersurfaces as well as complete
intersections of codimension two which arise via conifold transitions.Comment: 6 pages, espcrc
Observation and Properties of the X(3872) Decaying to J/ÏÏ+Ïâ in pÂŻp Collisions at âs = 1.96 TeV
We report the observation of the X(3872) in the J/psi pi+pi- channel, with J/psi decaying to mu+mu- in p-p(bar) collisions at sqrt(s) = 1.96 TeV. Using approximately 230 pb^-1 of data collected with the Run II D0 detector, we observe 522 +/- 100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9 +/- 3.1 (stat.) +/- 3.0 (syst.) MeV/c^2. We have investigated the production and decay characteristics of the X(3872), and find them to be similar to those of the psi(2S) state
K3-fibered Calabi-Yau threefolds I, the twist map
A construction of Calabi-Yaus as quotients of products of lower-dimensional
spaces in the context of weighted hypersurfaces is discussed, including
desingularisation. The construction leads to Calabi-Yaus which have a fiber
structure, in particular one case has K3 surfaces as fibers. These Calabi-Yaus
are of some interest in connection with Type II -heterotic string dualities in
dimension 4. A section at the end of the paper summarises this for the
non-expert mathematician.Comment: 31 pages LaTeX, 11pt, 2 figures. To appear in International Journal
of Mathematics. On the web at
http://personal-homepages.mis.mpg.de/bhunt/preprints.html , #
The web of Calabi-Yau hypersurfaces in toric varieties
Recent results on duality between string theories and connectedness of their
moduli spaces seem to go a long way toward establishing the uniqueness of an
underlying theory. For the large class of Calabi-Yau 3-folds that can be
embedded as hypersurfaces in toric varieties the proof of mathematical
connectedness via singular limits is greatly simplified by using polytopes that
are maximal with respect to certain single or multiple weight systems. We
identify the multiple weight systems occurring in this approach. We show that
all of the corresponding Calabi-Yau manifolds are connected among themselves
and to the web of CICY's. This almost completes the proof of connectedness for
toric Calabi-Yau hypersurfaces.Comment: TeX, epsf.tex; 24 page
GKZ-Generalized Hypergeometric Systems in Mirror Symmetry of Calabi-Yau Hypersurfaces
We present a detailed study of the generalized hypergeometric system
introduced by Gel'fand, Kapranov and Zelevinski (GKZ-hypergeometric system) in
the context of toric geometry. GKZ systems arise naturally in the moduli theory
of Calabi-Yau toric varieties, and play an important role in applications of
the mirror symmetry. We find that the Gr\"obner basis for the so-called toric
ideal determines a finite set of differential operators for the local solutions
of the GKZ system. At the special point called the large radius limit, we find
a close relationship between the principal parts of the operators in the GKZ
system and the intersection ring of a toric variety. As applications, we
analyze general three dimensional hypersurfaces of Fermat and non-Fermat types
with Hodge numbers up to . We also find and analyze several non
Landau-Ginzburg models which are related to singular models.Comment: 55 pages, 3 Postscript figures, harvma
Patterns in Calabi-Yau Distributions
We explore the distribution of topological numbers in CalabiâYau manifolds, using the KreuzerâSkarke dataset of hypersurfaces in toric varieties as a testing ground. While the Hodge numbers are well-known to exhibit mirror symmetry, patterns in frequencies of combination thereof exhibit striking new patterns. We find pseudo-Voigt and Planckian distributions with high confidence and exact fit for many substructures. The patterns indicate typicality within the landscape of CalabiâYau manifolds of various dimension
Search for R-parity violating supersymmetry via the LLE couplings lambda_{121}, lambda_{122} or lambda_{133} in ppbar collisions at sqrt(s)=1.96 TeV
A search for gaugino pair production with a trilepton signature in the
framework of R-parity violating supersymmetry via the couplings lambda_121,
lambda_122, or lambda_133 is presented. The data, corresponding to an
integrated luminosity of L~360/pb, were collected from April 2002 to August
2004 with the D0 detector at the Fermilab Tevatron Collider, at a
center-of-mass energy of sqrt(s)=1.96 TeV. This analysis considers final states
with three charged leptons with the flavor combinations eel, mumul, and eetau
(l=e or mu). No evidence for supersymmetry is found and limits at the 95%
confidence level are set on the gaugino pair production cross section and lower
bounds on the masses of the lightest neutralino and chargino are derived in two
supersymmetric models.Comment: 9 pages, 4 figures (fig2 includes 3 subfigures
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