The spin contribution to the form factor of quantum graphs

Following the quantisation of a graph with the Dirac operator (spin-1/2) we explain how additional weights in the spectral form factor K(\tau) due to spin propagation around orbits produce higher order terms in the small-\tau asymptotics in agreement with symplectic random matrix ensembles. We determine conditions on the group of spin rotations sufficient to generate CSE statistics.Comment: 9 page

Spectral Statistics for the Dirac Operator on Graphs

We determine conditions for the quantisation of graphs using the Dirac operator for both two and four component spinors. According to the Bohigas-Giannoni-Schmit conjecture for such systems with time-reversal symmetry the energy level statistics are expected, in the semiclassical limit, to correspond to those of random matrices from the Gaussian symplectic ensemble. This is confirmed by numerical investigation. The scattering matrix used to formulate the quantisation condition is found to be independent of the type of spinor. We derive an exact trace formula for the spectrum and use this to investigate the form factor in the diagonal approximation

The Unusual Luminosity Function of the Globular Cluster M10

We present the I-band luminosity function of the differentially reddened globular cluster M10. We combine photometric analysis derived from wide-field (23' x 23') images that include the outer regions of the cluster and high-resolution images of the cluster core. After making corrections for incompleteness and field star contamination, we find that the relative numbers of stars on the lower giant branch and near the main-sequence turnoff are in good agreement with theoretical predictions. However, we detect significant (> 6 \sigma) excesses of red giant branch stars above and below the red giant branch bump using a new statistic (a population ratio) for testing relative evolutionary timescales of main-sequence and red giant stars. The statistic is insensitive to assumed cluster chemical composition, age, and main-sequence mass function. The excess number of red giants cannot be explained by reasonable systematic errors in our assumed cluster chemical composition, age, or main-sequence mass function. Moreover, M10 shows excesses when compared to the cluster M12, which has nearly identical metallicity, age, and color-magnitude diagram morphology. We discuss possible reasons for this anomaly, finding that the most likely cause is a mass function slope that shows significant variations as a function of mass.Comment: 31 pages, 12 figures, accepted for Ap

3-Hy­droxy-2-[(2E)-1-(2-hy­droxy-6-oxocyclo­hex-1-en-1-yl)-3-(2-meth­oxy­phen­yl)prop-2-en-1-yl]cyclo­hex-2-en-1-one

In the title compound, C22H24O5, each of the cyclo­hexenone rings adopts a half-chair conformation. The hy­droxy and carbonyl O atoms face each other and are orientated to allow for the formation of the two intra­molecular O—H⋯O hydrogen bonds which are typical of xanthene derivatives. In the crystal, weak inter­molecular C—H⋯O hydrogen bonds link mol­ecules into layers parallel to the ab plane

Indiana University Pervasive Technology Institute – Research Technologies: XSEDE Service Provider and XSEDE subcontract report (PY1: 1 July 2011 to 30 June 2012)

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF or XSEDE leadership.This document is a summary of the activities of the Research Technologies division of UITS, a Service & Cyberinfrastructure Center affiliated with the Indiana University Pervasive Technology Institute, as part of the eXtreme Science and Engineering Discovery Environment (XSEDE) during XSEDE Program Year 1 (1 July 2011 – 30 June 2012). This document consists of three parts: - Section 2 of this document describes IU’s activities as an XSEDE Service Provider, using the format prescribed by XSEDE for reporting such activities. - Section 3 of this document describes IU’s activities as part of XSEDE management, operations, and support activities funded under a subcontract from the National Center for Supercomputer Applications (NCSA), the lead organization for XSEDE. This section is organized by the XSEDE Work Breakdown Structure (WBS) plan. - Appendix 1 is a summary table of IU’s education, outreach, and training events funded and supported in whole or in part by IU’s subcontract from NCSA as part of XSEDE.This document was developed with support from National Science Foundation (NSF) grant OCI-1053575

The Luminosity Function and Color-Magnitude Diagram of the Globular Cluster M12

In this paper we present the V and I luminosity functions and color-magnitude diagrams derived from wide-field (23 arcmin by 23 arcmin) BVI photometry of the intermediate metallicity ([Fe/H]=-1.3) Galactic globular cluster M12. Using observed values (and ranges of values) for the cluster metallicity, reddening, distance modulus, and age we compare these data to recent alpha-enhanced stellar evolution models for low mass metal-poor stars. We describe several methods of making comparisons between theoretical and observed luminosity functions in order to isolate the evolutionary timescale information the luminosity functions contain. We find no significant evidence of excesses of stars on the red giant branch, although the morphology of the subgiant branch in the observed luminosity function does not match theoretical predictions in a satisfactory way. Current uncertainties in Teff-color transformations (and possibly also in other physics inputs to the models) make more detailed conclusions about the subgiant branch morphology impossible. Given the recent constraints on cluster ages from the WMAP experiment (Spergel et al. 2003), we find that good fitting models that do not include He diffusion (both color-magnitude diagrams and luminosity functions) are too old (by approximately 1-2 Gyr) to adequately represent the cluster luminosity function. The inclusion of helium diffusion in the models provides an age reduction (compared to non-diffusive models) that is consistent with the age of the universe being 13.7+/-0.2 Gyr (Bennett et al. 2003).Comment: 63 pages, 29 figures, accepted for ApJ. Quality of images are degraded; please e-mail lead author for high-quality PS/PDF preprin

Dark Matter Candidates: A Ten-Point Test

An extraordinarily rich zoo of non-baryonic Dark Matter candidates has been proposed over the last three decades. Here we present a 10-point test that a new particle has to pass, in order to be considered a viable DM candidate: I.) Does it match the appropriate relic density? II.) Is it {\it cold}? III.) Is it neutral? IV.) Is it consistent with BBN? V.) Does it leave stellar evolution unchanged? VI.) Is it compatible with constraints on self-interactions? VII.) Is it consistent with {\it direct} DM searches? VIII.) Is it compatible with gamma-ray constraints? IX.) Is it compatible with other astrophysical bounds? X.) Can it be probed experimentally?Comment: 29 pages, 12 figure

Spectral Statistics for the Dirac Operator on Graphs

We determine conditions for the quantisation of graphs using the Dirac operator for both two and four component spinors. According to the Bohigas-Giannoni-Schmit conjecture for such systems with time-reversal symmetry the energy level statistics are expected, in the semiclassical limit, to correspond to those of random matrices from the Gaussian symplectic ensemble. This is confirmed by numerical investigation