7,191 research outputs found

    Hadronic physics at KLOE

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    New KLOE results on scalar mesons, γγ\gamma\gamma physics and η\eta physics are presented.Comment: 4 pages, 5 postscript figures, contributed to the Proceedings of CIPANP 2009: 10th Conference on the Intersections of Particle and Nuclear Physics, San Diego, USA, 26-31 May, 200

    Dark Matter and IMF normalization in Virgo dwarf early-type galaxies

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    In this work we analyze the dark matter (DM) fraction, fDMf_{DM}, and mass-to-light ratio mismatch parameter, δIMF\delta_{IMF} (computed with respect to a Milky-Way-like IMF), for a sample of 39 dwarf early-type galaxies (dEs) in the Virgo cluster. Both fDMf_{DM} and δIMF\delta_{IMF} are estimated within the central (one effective radius) galaxy regions, with a Jeans dynamical analysis that relies on galaxy velocity dispersions, structural parameters, and stellar M/L ratios from the SMAKCED survey. In this first attempt to constrain, simultaneously, the IMF normalization and the DM content, we explore the impact of different assumptions on the DM model profile. On average, for a NFW profile, the δIMF\delta_{IMF} is consistent with a Chabrier-like normalization (δIMF1\delta_{IMF} \sim 1), with fDM0.35f_{DM} \sim 0.35. One of the main results of the present work is that for at least a few systems the δIMF\delta_{IMF} is heavier than the MW-like value (i.e. either top- or bottom-heavy). When introducing tangential anisotropy, larger δIMF\delta_{IMF} and smaller fDMf_{DM} are derived. Adopting a steeper concentration-mass relation than that from simulations, we find lower δIMF\delta_{IMF} (<1< 1) and larger fDMf_{DM}. A constant M/L profile with null fDMf_{DM} gives the heaviest δIMF\delta_{IMF} (2\sim 2). In the MONDian framework, we find consistent results to those for our reference NFW model. If confirmed, the large scatter of δIMF\delta_{IMF} for dEs would provide (further) evidence for a non-universal IMF in early-type systems. On average, our reference fDMf_{DM} estimates are consistent with those found for low-σe\sigma_{e} (100kms1\rm \sim 100 \, \rm km s^{-1}) early-type galaxies (ETGs). Furthermore, we find fDMf_{DM} consistent with values from the SMAKCED survey, and find a double-value behavior of fDMf_{DM} with stellar mass, which mirrors the trend of dynamical M/L and global star formation efficiency with mass.Comment: 11 pages, 3 figures, 1 table, published on MNRAS. Figure 1 has been updated with respect to version 1, including the range of values found if the S\'ersic index, n, is varied from 0.5 to 2 (dark-green curves

    A precise new KLOE measurement of Fπ2|F_\pi|^2 with ISR events and determination of ππ\pi\pi contribution to aμa_\mu for 0.592<Mππ<0.9750.592 < M_{\pi\pi} < 0.975 GeV

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    The KLOE experiment at the DAΦ\PhiNE ϕ\phi-factory has performed a new precise measurement of the pion form factor using Initial State Radiation events, with photons emitted at small polar angle. Results based on an integrated luminosity of 240 pb1^{-1} and extraction of the ππ\pi\pi contribution to aμa_\mu in the mass range 0.35<Mππ2<0.950.35< M^2_{\pi\pi}<0.95 GeV2^2 are presented. The new value of aμππa^{\pi\pi}_\mu has smaller (30%) statistical and systematic error and is consistent with the KLOE published value (confirming the current disagreement between the standard model prediction for aμa_\mu and the measured value).Comment: 5 pages, proceedings for the CIPANP 2009 conferenc

    Protecting the SWAP\sqrt{SWAP} operation from general and residual errors by continuous dynamical decoupling

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    We study the occurrence of errors in a continuously decoupled two-qubit state during a SWAP\sqrt{SWAP} quantum operation under decoherence. We consider a realization of this quantum gate based on the Heisenberg exchange interaction, which alone suffices for achieving universal quantum computation. Furthermore, we introduce a continuous-dynamical-decoupling scheme that commutes with the Heisenberg Hamiltonian to protect it from the amplitude damping and dephasing errors caused by the system-environment interaction. We consider two error-protection settings. One protects the qubits from both amplitude damping and dephasing errors. The other features the amplitude damping as a residual error and protects the qubits from dephasing errors only. In both settings, we investigate the interaction of qubits with common and independent environments separately. We study how errors affect the entanglement and fidelity for different environmental spectral densities.Comment: Extended version of arXiv:1005.1666. To appear in PR

    Unifying static analysis of gravitational structures with a scale-dependent scalar field gravity as an alternative to dark matter

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    Aims. We investigated the gravitational effects of a scalar field within scalar-tensor gravity as an alternative to dark matter. Motivated by chameleon, symmetron and f(R)-gravity models, we studied a phenomenological scenario where the scalar field has both a mass (i.e. interaction length) and a coupling constant to the ordinary matter which scale with the local properties of the considered astrophysical system. Methods. We analysed the feasibility of this scenario using the modified gravitational potential obtained in its context and applied it to the galactic and hot gas/stellar dynamics in galaxy clusters and elliptical/spiral galaxies respectively. This is intended to be a first step in assessing the viability of this new approach in the context of "alternative gravity" models. Results. The main results are: 1. the velocity dispersion of elliptical galaxies can be fitted remarkably well by the suggested scalar field, with model significance similar to a classical Navarro-Frenk-White dark halo profile; 2. the analysis of the stellar dynamics and the gas equilibrium in elliptical galaxies has shown that the scalar field can couple with ordinary matter with different strengths (different coupling constants) producing and/or depending on the different clustering state of matter components; 3. elliptical and spiral galaxies, combined with clusters of galaxies, show evident correlations among theory parameters which suggest the general validity of our results at all scales and a way toward a possible unification of the theory for all types of gravitational systems we considered. All these results demonstrate that the proposed scalar field scenario can work fairly well as an alternative to dark matter.Comment: 23 pages, 15 figures, 5 tables, accepted for publication on Astronomy & Astrophysic

    Preface of minisymposium "Fifth Symposium on mathematical modelling of hydrological sciences"

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    The challenges that poses the hydrological sciences require a lot of efforts, especially in the development and improvement of mathematical models. The need to understand deeply the phenomena puts us in the condition of create models that are more accurate, but at the same time increase their simplicity and reliability. It is therefore important to be provided with high-quality data, whether observed or simulated samples through appropriate software. Statistical models are a constant in all the works of this symposium, which are needed to verify the reliability of empirical literature expression, to predict floods, rainfalls and important economic quantities and to identify the main influencing factors of pluviometric regimes. In this Minisymposium all these problems are faced with original solutions, to contribute the development of hydrology on science pathway. Predicting precipitation is the main focus of Latini et al. [1], who use probabilistic statistical models to estimate the monthly precipitation in the Midwest U.S. area using forecasts of temperature at the resolution of ~30km. The main aim of Bertini et al. [2] is to define the optimal location of rain gauges within a measuring network in Mignone River basin, using a multi-objective optimization approach based on hydrological models. The authors in Moccia and Mineo [3] investigate the influence of time series length in estimating the intensity-duration-frequency curves using observations of annual maxima rainfall in Lazio region. Mineo et al. [4] provide monthly erosivity maps for the Lazio region using the density approach introduced in Revised Unviersal Soil Loss Equation

    The qualitative assessment of responsiveness to environmental challenge in horses and ponies.

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    The responsiveness of 10 horses and 10 ponies to environmental challenge (represented by an open field test) was assessed using a qualitative approach based on free choice profiling methodology (FCP), which gives observers complete freedom to choose their own descriptive terms. Data were analysed with generalised Procrustes analysis (GPA), a multivariate statistical technique associated with FCP. A cross-validation of the outcomes of this approach to data recorded through quantitative behaviour analysis, and through a questionnaire given to the animals’ owner/riding instructor, was also performed using principal component analysis (PCA). Twelve undergraduate students generated their own descriptive vocabularies, by watching 20 horse/pony video clips lasting 2.5 min each. GPA showed that the consensus profile explained a high percentage of variation among the 12 observers, and differed significantly from the mean randomised profile ( p < 0.001). Two main dimensions of the consensus profile were identified, explaining 60% and 5.2% of the variation between animals, respectively. The 12 observer word charts interpreting these dimensions were semantically consistent, as they all converged towards the same meaning, albeit using different terms. The most used term to describe the positive end of axis 1 was ‘‘quiet’’, whereas ‘‘attentive’’ was the best positive descriptor of axis 2. The most frequently used descriptors for the negative ends of axes 1 and 2 were ‘‘nervous’’ and ‘‘bored’’, respectively. Thus, axis 1 was labelled as ‘‘quiet/nervous’’ and axis 2 was named as ‘‘attentive/bored’’. A marked effect of animal category was observed on the scores of the animals on the first dimension ( p < 0.001). Horses received significantly higher scores, and were thus assessed as more quiet and calm, than ponies. Conversely, ponies tended to receive lower scores on the second dimension ( p < 0.12), therefore they appeared less curious and attentive. The results of the PCA showed that the variables from different types of measurement clearly had meaningful relationships. For instance, the variables with the highest loading on the positive end of axis 1 were all indicative of tractable and docile animals, whereas axis 2 showed high loadings on the positive end for variables indicating attentive animals. Qualitative behaviour assessment proved to be an appropriate methodology for the study of horse behavioural responsiveness, in that it provided a multifaceted characterisation of horse behavioural expression that was in agreement with other quantitative and subjective assessments of the animals’ behaviour

    Influence of space allowance on the welfare of weaned buffalo (Bubalus Bubalis) calves

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    Twenty weaned female buffalo calves were used to evaluate the effect of space allowance in relation to their body surface area on a range of behavioural and physiological parameters. Body surface area in m2 was calculated as 0.12 body weight0.60. Ten calves received 50% of body surface as space allocation (Group 50), 10 others received 90% of body surface area (Group 90). Animals in Group 50 lay with a lower number of outstretched legs than calves in Group 90. Buffaloes from Group 50 were observed standing more frequently than animals from Group 90 ( P < 0.001). The proportions of idling ( P < 0.01) and lying idle observations ( P < 0.001) were higher for Group 90 than for Group 50. Group 90 performed a higher number of non-agonistic interactions than Group 50 ( P < 0.01), whereas the opposite was observed for the number of agonistic interactions ( P < 0.01). When exposed to open field testing, Group 50 animals displayed an increased duration of movement, number of galloping events and more vocalisation. Neither immune responses to phytohemagglutinin and ovalbumin nor the cortisol response to exogenous ACTH were affected by treatment. It was concluded that 50% of body surface area may be an inadequate space allowance for weaned calves
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