Bures volume of the set of mixed quantum states

We compute the volume of the N^2-1 dimensional set M_N of density matrices of size N with respect to the Bures measure and show that it is equal to that of a N^2-1 dimensional hyper-halfsphere of radius 1/2. For N=2 we obtain the volume of the Uhlmann 3-D hemisphere, embedded in R^4. We find also the area of the boundary of the set M_N and obtain analogous results for the smaller set of all real density matrices. An explicit formula for the Bures-Hall normalization constants is derived for an arbitrary N.Comment: 15 revtex pages, 2 figures in .eps; ver. 3, Eq. (4.19) correcte

Tevatron-for-LHC Report of the QCD Working Group

The experiments at Run 2 of the Tevatron have each accumulated over 1 inverse femtobarn of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focussed on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop.Comment: 156 pages, Tevatron-for-LHC Conference Report of the QCD Working Grou

Covariance and Fisher information in quantum mechanics

Variance and Fisher information are ingredients of the Cramer-Rao inequality. We regard Fisher information as a Riemannian metric on a quantum statistical manifold and choose monotonicity under coarse graining as the fundamental property of variance and Fisher information. In this approach we show that there is a kind of dual one-to-one correspondence between the candidates of the two concepts. We emphasis that Fisher informations are obtained from relative entropies as contrast functions on the state space and argue that the scalar curvature might be interpreted as an uncertainty density on a statistical manifold.Comment: LATE

A Prograde, Low-Inclination Orbit for the Very Hot Jupiter WASP-3b

We present new spectroscopic and photometric observations of the transiting exoplanetary system WASP-3. Spectra obtained during two separate transits exhibit the Rossiter-McLaughlin (RM) effect and allow us to estimate the sky-projected angle between the planetary orbital axis and the stellar rotation axis, lambda = 3.3^{+2.5}_{-4.4} degrees. This alignment between the axes suggests that WASP-3b has a low orbital inclination relative to the equatorial plane of its parent star. During our first night of spectroscopic measurements, we observed an unexpected redshift briefly exceeding the expected sum of the orbital and RM velocities by 140 m/s. This anomaly could represent the occultation of material erupting from the stellar photosphere, although it is more likely to be an artifact caused by moonlight scattered into the spectrograph.Comment: 23 pages, 4 figures, Accepted for publication in The Astrophysical Journal, Replacement includes revised citation

Radio-frequency discharges in Oxygen. Part 1: Modeling

In this series of three papers we present results from a combined experimental and theoretical effort to quantitatively describe capacitively coupled radio-frequency discharges in oxygen. The particle-in-cell Monte-Carlo model on which the theoretical description is based will be described in the present paper. It treats space charge fields and transport processes on an equal footing with the most important plasma-chemical reactions. For given external voltage and pressure, the model determines the electric potential within the discharge and the distribution functions for electrons, negatively charged atomic oxygen, and positively charged molecular oxygen. Previously used scattering and reaction cross section data are critically assessed and in some cases modified. To validate our model, we compare the densities in the bulk of the discharge with experimental data and find good agreement, indicating that essential aspects of an oxygen discharge are captured.Comment: 11 pages, 10 figure

Glutamatergic medication in the treatment of obsessive compulsive disorder (OCD) and autism spectrum disorder (ASD) - study protocol for a randomised controlled trial

BACKGROUND: Compulsivity is a cross-disorder trait underlying phenotypically distinct psychiatric disorders that emerge in childhood or adolescence. Despite the effectiveness of serotonergic compounds in the treatment of obsessive-compulsive disorder, treatment-resistant symptoms remaining in 40 to 60 % of patients present a pressing clinical problem. There are currently no medications that effectively treat the core impairments of autism spectrum disorder. There is an urgent need for the development of conceptually novel pharmacological strategies. Agents targeting glutamate neurotransmission, such as memantine, represent promising candidates. This proof-of-concept clinical study will allow pilot-testing of memantine for both clinical effectiveness and tolerability/safety. Memantine is an N-methyl-D-aspartate receptor antagonist, approved for the treatment of Alzheimer's dementia in a number of countries. METHODS/DESIGN: This 12-week study has an add-on, randomised, double-blind, placebo-controlled design of treatment with memantine, including an up-titration phase (forced flexible dose design, 5-15 mg/day), in patients aged 6-17 years and 9 months with obsessive-compulsive disorder or autism spectrum disorder. It is planned to include patients with obsessive-compulsive disorder (N = 50) or autism spectrum disorder (N = 50) across four centres in three European countries. Patients will be randomly assigned to memantine or placebo in a 1:1 ratio. Primary objectives are the investigation of the effectiveness of memantine in paediatric patients for improving symptoms of compulsivity (primary outcome measure: total score on the Children's Yale-Brown Obsessive-Compulsive Scale) and to explore its tolerability and safety. Secondary objectives are to explore the effects of memantine at the level of structure, function and biochemistry of the fronto-striatal circuits, and to collect blood for genetic analyses and biomarkers. Tertiary objectives are to explore the role of new candidate genes and pathways for compulsivity by linking genes to clinical phenotypes, response to treatment, neurocognitive test performance, and key structural and functional neuroimaging measures of the fronto-striatal circuits and to explore biomarkers/proteomics for compulsivity traits. DISCUSSION: This study is part of the large, translational project TACTICS ( http://www.tactics-project.eu/ ) that is funded by the European Union and investigates the neural, genetic and molecular factors involved in the pathogenesis of compulsivity. Its results will provide clinically relevant solid information on potential new mechanisms and medication treatment in obsessive-compulsive and autism spectrum disorders. TRIAL REGISTRATION: EudraCT Number: 2014-003080-38 , date of registration: 14 July 2014

Search for the lepton-family-number nonconserving decay \mu -> e + \gamma

The MEGA experiment, which searched for the muon- and electron-number violating decay \mu -> e + \gamma, is described. The spectrometer system, the calibrations, the data taking procedures, the data analysis, and the sensitivity of the experiment are discussed. The most stringent upper limit on the branching ratio of \mu -> e + \gamma) < 1.2 x 10^{-11} was obtained

Magnetic inflation and Stellar Mass. II. On the radii of wingle, rapidly rotating, fully convective M-dwarf stars

Main-sequence, fully convective M dwarfs in eclipsing binaries are observed to be larger than stellar evolutionary models predict by as much as 10%–15%. A proposed explanation for this discrepancy involves effects from strong magnetic fields, induced by rapid rotation via the dynamo process. Although, a handful of single, slowly rotating M dwarfs with radius measurements from interferometry also appear to be larger than models predict, suggesting that rotation or binarity specifically may not be the sole cause of the discrepancy. We test whether single, rapidly rotating, fully convective stars are also larger than expected by measuring their $R\sin i$ distribution. We combine photometric rotation periods from the literature with rotational broadening ($v\sin i$) measurements reported in this work for a sample of 88 rapidly rotating M dwarf stars. Using a Bayesian framework, we find that stellar evolutionary models underestimate the radii by 10 \% \mbox{--}15{ \% }_{-2.5}^{+3}, but that at higher masses (0.18 < M < 0.4 M Sun), the discrepancy is only about 6% and comparable to results from interferometry and eclipsing binaries. At the lowest masses (0.08 < M < 0.18 M Sun), we find that the discrepancy between observations and theory is 13%–18%, and we argue that the discrepancy is unlikely to be due to effects from age. Furthermore, we find no statistically significant radius discrepancy between our sample and the handful of M dwarfs with interferometric radii. We conclude that neither rotation nor binarity are responsible for the inflated radii of fully convective M dwarfs, and that all fully convective M dwarfs are larger than models predict.The authors would like to thank the referee for the thoughtful report, which greatly improved the manuscript. The authors would also like to thank Lisa Prato and Larissa Nofi for IGRINS training, and Heidi Larson, Jason Sanborn, and Andrew Hayslip for operating the DCT during our observations. We would also like to thank Jen Winters, Jonathan Irwin, Paul Dalba, Mark Veyette, Eunkyu Han, and Andrew Vanderburg for useful discussions and helpful comments on this work. Some of this work was supported by the NASA Exoplanet Research Program (XRP) under grant No. NNX15AG08G issued through the Science Mission Directorate.These results made use of the Lowell Observatory's Discovery Channel Telescope, supported by Discovery Communications, Inc., Boston University, the University of Maryland, the University of Toledo and Northern Arizona University; the Immersion Grating Infrared Spectrograph (IGRINS) that was developed under a collaboration between the University of Texas at Austin and the Korea Astronomy and Space Science Institute (KASI) with the financial support of the US National Science Foundation under grant AST-1229522, of the University of Texas at Austin, and of the Korean GMT Project of KASI; data taken at The McDonald Observatory of The University of Texas at Austin; and data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by NASA and the NSF. (NNX15AG08G - NASA Exoplanet Research Program (XRP); Discovery Communications, Inc.; Boston University; University of Maryland; University of Toledo; Northern Arizona University; AST-1229522 - US National Science Foundation; University of Texas at Austin; Korean GMT Project of KASI; NASA; NSF

Discovery and Precise Characterization by the MEarth Project of LP 661-13, an Eclipsing Binary Consisting of Two Fully Convective Low-mass Stars

We report the detection of stellar eclipses in the LP 661-13 system. We present the discovery and characterization of this system, including high resolution spectroscopic radial velocities and a photometric solution spanning two observing seasons. LP 661-13 is a low mass binary system with an orbital period of $4.7043512^{+0.0000013}_{-0.0000010}$ days at a distance of $24.9 \pm 1.3$ parsecs. LP 661-13A is a $0.30795 \pm 0.00084$ $M_\odot$ star while LP 661-13B is a $0.19400 \pm 0.00034$ $M_\odot$ star. The radius of each component is $0.3226 \pm 0.0033$ $R_\odot$ and $0.2174 \pm 0.0023$ $R_\odot$, respectively. We detect out of eclipse modulations at a period slightly shorter than the orbital period, implying that at least one of the components is not rotating synchronously. We find that each component is slightly inflated compared to stellar models, and that this cannot be reconciled through age or metallicity effects. As a nearby eclipsing binary system where both components are near or below the full-convection limit, LP 661-13 will be a valuable test of models for the structure of cool dwarf stars.Comment: 24 pages, 8 tables, 6 figures. Submitted to ApJ, comments welcom