50,338 research outputs found

    The Incidence of Magnetic Fields in Massive Stars: An Overview of the MiMeS Survey Component

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    With only a handful of known magnetic massive stars, there is a troubling deficit in the scope of our knowledge of the influence of magnetic fields on stellar evolution, and almost no empirical basis for understanding how fields modify mass loss and rotation in massive stars. Most remarkably, there is still no solid consensus regarding the origin physics of these fields - whether they are fossil remnants, or produced by contemporaneous dynamos, or some combination of these mechanisms. This article will present an overview of the Survey Component of the MiMeS Large Programs, the primary goal of which is to search for Zeeman signatures in the circular polarimetry of massive stars (stars with spectral types B3 and hotter) that were previously unknown to host any magnetic field. To date, the MiMeS collaboration has collected more than 550 high-resolution spectropolarimetric observations with ESPaDOnS and Narval of nearly 170 different stars, from which we have discovered 14 new magnetic stars.Comment: 7 pages (+1 for questions), 3 figures, to appear in proceedings of Stellar polarimetry: From birth to deat

    New Measurements of the EMC Effect in Few-Body Nuclei

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    Measurements of the EMC effect show that the quark distributions in nuclei are not simply the sum of the quark distributions of the constituent nucleons. However, interpretation of the EMC effect is limited by the lack of a reliable baseline calculation of the effects of Fermi motion and nucleon binding. We present preliminary results from JLab experiment E03-103, a precise measurement of the EMC effect in few-body and heavy nuclei. These data emphasize the large-x region, where binding and Fermi motion effects dominate, and thus will provide much better constraints on the effects of binding. These data will also allow for comparisons to calculations for few-body nuclei, where the uncertainty in the nuclear structure is minimized.Comment: Proceedings from talk at the Topical Group on Hadron Physics meeting, Nashville Tennessee, October 22-24, 2006. 9 pages, 6 figure

    Overview on jet results from STAR

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    Full jet reconstruction allows access to the parton kinematics over a large energy domain and can be used to constrain the mechanisms of energy loss in heavy-ion collisions. Such measurements are challenging at RHIC, due to the high-multiplicity environments created in heavy-ion collisions. In these proceedings, we report an overview of the results on full jet reconstruction obtained by the STAR experiment. Jet measurements in 200 GeV p+p show that jets are calibrated pQCD probes and provide a baseline for jet measurements in Au+Au collisions. Inclusive differential jet production cross sections and ratios are reported for central 200 GeV Au+Au collisions and compared to p+p. We also present measurements of fully reconstructed di-jets at mid-rapidity, and compare spectra and fragmentation functions in p+p and central Au+Au collisions.Comment: Proceedings for the 26th WWND conferenc

    Jet-hadron correlations in STAR

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    Advancements in full jet reconstruction have made it possible to use jets as triggers in azimuthal angular correlations to study the modification of hard-scattered partons in the medium created in ultrarelativistic heavy-ion collisions. This increases the range of parton energies accessible in these analyses and improves the signal-to-background ratio compared to dihadron correlations. Results of a systematic study of jet-hadron correlations in central Au-Au collisions at sqrt(s_NN) = 200 GeV are indicative of a broadening and softening of jets which interact with the medium. Furthermore, jet-hadron correlations suggest that the suppression of the associated hadron yield at high-pT is balanced in large part by low-pT enhancement.Comment: 4 pages, 2 figures, proceedings for Quark Matter 201

    Present status and future prospects for a Higgs boson discovery at the Tevatron and LHC

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    Discovering the Higgs boson is one of the primary goals of both the Tevatron and the Large Hadron Collider (LHC). The present status of the Higgs search is reviewed and future prospects for discovery at the Tevatron and LHC are considered. This talk focuses primarily on the Higgs boson of the Standard Model and its minimal supersymmetric extension. Theoretical expectations for the Higgs boson and its phenomenological consequences are reviewed.Comment: 13 pages, 9 figures, 2 tables, jpconf documentclass file, invited talk at PASCOS 2010, the 16th International Symposium on Particles, Strings and Cosmology, Valencia, Spain, 19--23 July 201

    CoRoT's first seven planets: An overview

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    The up to 150 day uninterrupted high-precision photometry of about 100000 stars - provided so far by the exoplanet channel of the CoRoT space telescope - gave a new perspective on the planet population of our galactic neighbourhood. The seven planets with very accurate parameters widen the range of known planet properties in almost any respect. Giant planets have been detected at low metallicity, rapidly rotating and active, spotted stars. CoRoT-3 populated the brown dwarf desert and closed the gap of measured physical properties between standard giant planets and very low mass stars. CoRoT extended the known range of planet masses down to 5 Earth masses and up to 21 Jupiter masses, the radii to less than 2 Earth radii and up to the most inflated hot Jupiter found so far, and the periods of planets discovered by transits to 9 days. Two CoRoT planets have host stars with the lowest content of heavy elements known to show a transit hinting towards a different planet-host-star-metallicity relation then the one found by radial-velocity search programs. Finally the properties of the CoRoT-7b prove that terrestrial planets with a density close to Earth exist outside the Solar System. The detection of the secondary transit of CoRoT-1 at the 10−510^{-5}-level and the very clear detection of the 1.7 Earth radii of CoRoT-7b at 3.510−43.5 10^{-4} relative flux are promising evidence of CoRoT being able to detect even smaller, Earth sized planets.Comment: 8 pages, 19 figures and 3 table

    Targeted searches for gravitational waves from radio pulsars

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    An overview of the searches for gravitational waves from radio pulsars with LIGO and GEO is given. We give a brief description of the algorithm used in these targeted searches and provide end-to-end validation of the technique through hardware injections. We report on some aspects of the recent S3/S4 LIGO and GEO search for signals from several pulsars. The gaussianity of narrow frequency bands of S3/S4 LIGO data, where pulsar signals are expected, is assessed with Kolmogorov-Smirnov tests. Preliminary results from the S3 run with a network of four detectors are given for pulsar J1939+2134
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