119732431
All complete intersection Calabi-Yau four-folds
A bstractWe present an exhaustive, constructive, classification of the Calabi-Yau four-folds which can be described as complete intersections in products of projective spaces. A comprehensive list of 921,497 configuration matrices which represent all topologically distinct types of complete intersection Calabi-Yau four-folds is provided and can be downloaded here. The manifolds have non-negative Euler characteristics in the range 0 ≤ χ ≤ 2610. This data set will be of use in a wide range of physical and mathematical applications. Nearly all of these four-folds are elliptically fibered and are thus of interest for F-theory model building.
55683300
Heterotic standard models from smooth Calabi-Yau three-folds
Lara B. Anderson1, James Gray2, Andre Lukas∗3, Eran Palti4 1Center for the Fundamental Laws of Nature, Jefferson Laboratory Harvard University, 17 Oxford Street, Cambridge, MA 02138, U.S.A. 2Arnold-Sommerfeld-Center for Theoretical Physics, Department fur Physik Ludwig-Maximilians-Universitat Munchen, Theresienstrase 37, 80333 Munchen, Germany. 3Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford, OX1 3NP, U.K. 4Centre de Physique Theorique, Ecole Polytechnique, CNRS, 91128 Palaiseau, France.
119385831
Gravitational instantons, extra dimensions and form fields.
A broad class of higher-dimensional instanton solutions are found for a theory which contains gravity, a scalar field and antisymmetric tensor fields of arbitrary rank. The metric used, a warp product of an arbitrary number of any compact Einstein manifolds, includes many of great interest in particle physics and cosmology. For example 4D FRW universes with additional dimensions compactified on a Calabi-Yau three fold, a torus, a compact hyperbolic manifold or a sphere are all included. It is shown that the solution of this form which dominates the Hartle Hawking path integral is always a higher-dimensional generalisation of a Hawking Turok instanton when the potential of the scalar field is such that these instantons can exist. On continuation to lorentzian signature such instantons give rise to a spacetime in which all of the spatial dimensions are of equal size and where the spatial topology is that of a sphere. The extra dimensions are thus not hidden. In the case where the potential for the scalar field is generated solely by a dilatonic coupling to the form fields we find no integrable instantons at all. In particular we find no integrable solutions of the type under consideration for the supergravity theories which are the low energy effective field theories of superstrings.
17764338
Yukawa Couplings in Heterotic Compactification
We present a practical, algebraic method for efficiently calculating the Yukawa couplings of a large class of heterotic compactifications on Calabi-Yau three-folds with non-standard embeddings. Our methodology covers all of, though is not restricted to, the recently classified positive monads over favourable complete intersection Calabi-Yau three-folds. Since the algorithm is based on manipulating polynomials it can be easily implemented on a computer. This makes the automated investigation of Yukawa couplings for large classes of smooth heterotic compactifications a viable possibility.
59154275
Two hundred heterotic standard models on smooth Calabi-Yau threefolds
We construct heterotic standard models by compactifying on smooth Calabi-Yau three-folds in the presence of purely Abelian internal gauge fields. A systematic search over complete intersection Calabi-Yau manifolds with less than six Kahler parameters leads to over 200 such models which we present. Each of these models has precisely the matter spectrum of the MSSM, at least one pair of Higgs doublets, the standard model gauge group and no exotics. For about 100 of these models there are, naively, four additional U(1) symmetries, however these are Green-Schwarz anomalous and, hence, massive. In the remaining cases, three U(1) symmetries are anomalous while the fourth, massless one can be spontaneously broken by singlet vacuum expectation values. The presence of additional global U(1) symmetries, together with the possibility of switching on singlet vacuum expectation values, leads to a rich phenomenology which is illustrated for a particular example. Our database of standard models, which can be further enlarged by simply extending the computer-based search, allows for a detailed and systematic phenomenological analysis of string standard models, covering issues such as the structure of Yukawa couplings, R-parity violation, proton stability and neutrino masses.
119425527
Moving five-branes in low-energy heterotic M theory
We construct cosmological solutions of four-dimensional effective heterotic M-theory with a moving five-brane and evolving dilaton and T modulus. It is shown that the five-brane generates a transition between two asymptotic rolling-radii solutions. Moreover, the five-brane motion always drives the solutions towards strong coupling asymptotically. We present an explicit example of a negative-time branch solution which ends in a brane collision accompanied by a small-instanton transition. The five-dimensional origin of some of our solutions is also discussed.
14193738
Cosmological Parameters from Eigenmode Analysis of Sloan Digital Sky Survey Galaxy Redshifts
We present estimates of cosmological parameters from the application of the Karhunen-Loeve transform to the analysis of the three-dimensional power spectrum of density fluctuations using Sloan Digital Sky Survey galaxy redshifts. We use Ωmh and fb = Ωb/Ωm to describe the shape of the power spectrum, σ for the (linearly extrapolated) normalization, and β to parameterize linear theory redshift-space distortions. On scales k 0.16 h Mpc-1, our maximum likelihood values are Ωmh = 0.264 ± 0.043, fb = 0.286 ± 0.065, σ = 0.966 ± 0.048, and β = 0.45 ± 0.12. When we take a prior on Ωb from the Wilkinson Microwave Anisotropy Probe (WMAP), we find Ωmh = 0.207 ± 0.030, which is in excellent agreement with WMAP and the Two-Degree Field. This indicates that we have reasonably measured the gross shape of the power spectrum, but we have difficulty breaking the degeneracy between Ωmh and fb, because the baryon oscillations are not resolved in the current spectroscopic survey window function.
55531346
REDESIGN OF THE ISIS MAIN MAGNET POWER SUPPLY STORAGE CHOKE
The ISIS facility, based at the Rutherford Appleton Laboratory in the UK, provides intense pulsed neutron and muon beams for condensed matter studies. As part of the facilities upgrade and refurbishment program, the 1MJ storage choke which forms part of the main magnet power supply system, will be replaced with a number of smaller units. The present storage choke, which consists of a split secondary winding transformer, is incorporated into a series-parallel resonant circuit known as the 'White circuit' [1]. This circuit ensures that each magnet receives identical currents, but is not subjected to excessive voltages. Although the storage choke is essentially a transformer, its secondary magnetising inductance is relatively low and a precisely defined value. This paper discusses the design and development of ten smaller units which will eventually replace the present equipment, and the testing of a one fifth scale model, which will be used to prove the technology.
118367130
The Sloan Digital Sky Survey Quasar Catalog. V. Seventh Data Release
We present the fifth edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog, which is based upon the SDSS Seventh Data Release. The catalog, which contains 105,783 spectroscopically confirmed quasars, represents the conclusion of the SDSS-I and SDSS-II quasar survey. The catalog consists of the SDSS objects that have luminosities larger than Mi = –22.0 (in a cosmology with H 0 = 70 km s–1 Mpc–1, Ω M = 0.3, and ΩΛ = 0.7), have at least one emission line with FWHM larger than 1000 km s–1 or have interesting/complex absorption features, are fainter than i 15.0, and have highly reliable redshifts. The catalog covers an area of 9380 deg2. The quasar redshifts range from 0.065 to 5.46, with a median value of 1.49; the catalog includes 1248 quasars at redshifts greater than 4, of which 56 are at redshifts greater than 5. The catalog contains 9210 quasars with i < 18; slightly over half of the entries have i < 19. For each object the catalog presents positions accurate to better than 01 rms per coordinate, five-band (ugriz) CCD-based photometry with typical accuracy of 0.03 mag, and information on the morphology and selection method. The catalog also contains radio, near-infrared, and X-ray emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3800-9200 A at a spectral resolution of 2000; the spectra can be retrieved from the SDSS public database using the information provided in the catalog. Over 96% of the objects in the catalog were discovered by the SDSS. We also include a supplemental list of an additional 207 quasars with SDSS spectra whose archive photometric information is incomplete.
14359163
The sloan digital sky survey quasar catalog. IV. Fifth data release
We present the fourth edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog. The catalog contains 77,429 objects; this is an increase of over 30,000 entries since the previous edition. The catalog consists of the objects in the SDSS Fifth Data Release that have luminosities larger than Mi = -22.0 (in a cosmology with H0 = 70 km s-1 Mpc-1, ΩM = 0.3, and ΩΛ = 0.7), have at least one emission line with FWHM larger than 1000 km s-1 or have interesting/complex absorption features, are fainter than i ≈ 15.0, and have highly reliable redshifts. The area covered by the catalog is ≈5740 deg2. The quasar redshifts range from 0.08 to 5.41, with a median value of 1.48; the catalog includes 891 quasars at redshifts greater than 4, of which 36 are at redshifts greater than 5. Approximately half of the catalog quasars have i < 19; nearly all have i < 21. For each object the catalog presents positions accurate to better than 0.2'' rms per coordinate, five-band (ugriz) CCD-based photometry with typical accuracy of 0.03 mag, and information on the morphology and selection method. The catalog also contains basic radio, near-infrared, and X-ray emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3800-9200 A at a spectral resolution of 2000; the spectra can be retrieved from the public database using the information provided in the catalog. The average SDSS colors of quasars as a function of redshift, derived from the catalog entries, are presented in tabular form. Approximately 96% of the objects in the catalog were discovered by the SDSS.
17368591
The Sloan Digital Sky Survey Science Archive: Migrating a Multi-Terabyte Astronomical Archive from Object to Relational DBMS
The Sloan Digital Sky Survey Science Archive is the first in a series of multi-Terabyte digital archives in Astronomy and other data-intensive sciences. To facilitate data mining in the SDSS archive, we adapted a commercial database engine and built specialized tools on top of it. Originally we chose an object-oriented database management system due to its data organization capabilities, platform independence, query performance and conceptual fit to the data. However, after using the object database for the first couple of years of the project, it soon began to fall short in terms of its query support and data mining performance. This was as much due to the inability of the database vendor to respond our demands for features and bug fixes as it was due to their failure to keep up with the rapid improvements in hardware performance, particularly faster RAID disk systems. In the end, we were forced to abandon the object database and migrate our data to a relational database. We describe below the technical issues that we faced with the object database and how and why we migrated to relational technology.