1,555 research outputs found

    First observation of two hyperfine transitions in antiprotonic He-3

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    We report on the first experimental results for microwave spectroscopy of the hyperfine structure of antiprotonic He-3. Due to the helium nuclear spin, antiprotonic He-3 has a more complex hyperfine structure than antiprotonic He-4 which has already been studied before. Thus a comparison between theoretical calculations and the experimental results will provide a more stringent test of the three-body quantum electrodynamics (QED) theory. Two out of four super-super-hyperfine (SSHF) transition lines of the (n,L)=(36,34) state were observed. The measured frequencies of the individual transitions are 11.12559(14) GHz and 11.15839(18) GHz, less than 1 MHz higher than the current theoretical values, but still within their estimated errors. Although the experimental uncertainty for the difference of these frequencies is still very large as compared to that of theory, its measured value agrees with theoretical calculations. This difference is crucial to be determined because it is proportional to the magnetic moment of the antiproton.Comment: 8 pages, 6 figures, just published (online so far) in Physics Letters

    Systematic study of the decay rates of antiprotonic helium states

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    A systematic study of the decay rates of antiprotonic helium (\pbhef and \pbhet) at CERN AD (Antiproton Decelerator) has been made by a laser spectroscopic method. The decay rates of some of its short-lived states, namely those for which the Auger rates γA\gamma_{\mathrm{A}} are much larger than their radiative decay rates (γrad1\gamma_{\mathrm{rad}} \sim 1 μ\mus1^{-1}), were determined from the time distributions of the antiproton annihilation signals induced by laser beams, and the widths of the atomic resonance lines. The magnitude of the decay rates, especially their relation with the transition multipolarity, is discussed and compared with theoretical calculations.Comment: 6 pages, 5 figures, and 1 tabl

    Precise laser spectroscopy of the antiprotonic helium atom and CPT test on antiproton mass and charge

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    We have measured twelve transition frequencies of the antiprotonic helium atom (pbar-He+) with precisions of 0.1--0.2 ppm using a laser spectroscopic method. The agreement between the experiment and theories was so good that we can put a limit on the proton-antiproton mass (or charge) difference. The new limit is expected to be much smaller than the already published value, 60 ppb.Comment: proceeding of the conference, "PANIC02

    Hyperfine structure of antiprotonic helium revealed by a laser-microwave-laser resonance method

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    Using a newly developed laser-microwave-laser resonance method, we observed a pair of microwave transitions between hyperfine levels of the (n,L)=(37,35)(n,L)=(37,35) state of antiprotonic helium. This experiment confirms the quadruplet hyperfine structure due to the interaction of the antiproton orbital angular momentum, the electron spin and the antiproton spin as predicted by Bakalov and Korobov. The measured frequencies of νHF+=12.89596±0.00034\nu_{\text HF}^+ =12.89596 \pm 0.00034 GHz and νHF=12.92467±0.00029\nu_{\text HF}^- =12.92467 \pm 0.00029 GHz agree with recent theoretical calculations on a level of 6×105 6 \times10^{-5}.Comment: 4 pages, 4 figures, 1 tabl

    H2_2 Emission Nebulosity Associated with KH 15D

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    An H2_2 emission filament is found in close proximity to the unique object KH 15D using the adaptive optics system of the Subaru Telescope. The morphology of the filament, the presence of spectroscopic outflow signatures observed by Hamilton et al., and the detection of extended H2_2 emission from KH 15D by Deming, Charbonneau, & Harrington suggest that this filament arises from shocked H2_2 in an outflow. The filament extends about 15" to the north of KH 15D.Comment: 11 pages, 3 figures, 1 table. Astrophysical Journal Letters, in pres

    Efficacy of escitalopram in the treatment of social anxiety disorder: A meta-analysis versus placebo

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    Escitalopram is the most selective of the serotonin reuptake inhibitor (SSRI) antidepressants. We conducted a meta-analysis of placebo-controlled studies where escitalopram was used to treat patients with social anxiety disorder (SAD). Data from all randomised, double-blind placebo-controlled studies in SAD with escitalopram from both specialist settings and general practice were used. Patients met the DSM-IV criteria for SAD, ?18 years old, Liebowitz Social Anxiety Scale (LSAS) ?60. The primary outcome measure was the estimated treatment difference in LSAS total score at Week 12. Secondary outcome measures included the estimated treatment difference in the Clinical Global Impression-Severity (CGI-S) score at Week 12. A total of 1598 patients from 3 randomised controlled trials were included in the analyses. Escitalopram (n=1,061) was superior to placebo (n=537), with an estimated treatment difference on the LSAS of ?9.2 points (95%CI: [?14.4; ?4.0], p<0.01) (escitalopram 5 mg/day), ?4.6 points (95%CI: [?8.1; ?1.0], p<0.01) (escitalopram 10 mg/day), ?10.1 points (95%CI: [?13.7; ?6.5], p<0.01) (escitalopram 20 mg/day) and ?7.3 points (95%CI: [?12.3; ?2.2], p<0.01) (escitalopram 10-20 mg/day). For the CGI-S, the corresponding values were ?0.55 points (95%CI: [?0.79; ?0.31], p<0.01) (escitalopram 5 mg/day), ?0.26 points (95%CI: [?0.42; ?0.10], p<0.01) (escitalopram 10 mg/day), ?0.48 points (95%CI: [?0.64; ?0.31], p<0.01) (escitalopram 20 mg/day) and ?0.29 points (95%CI: [?0.51; ?0.07], p<0.05) (escitalopram 10-20 mg/day). The withdrawal rate due to adverse events was 7.2% for escitalopram, compared with 4.3% for placebo (p<0.05). In this meta-analysis, all doses of escitalopram showed significant superiority in efficacy versus placebo in the treatment of patients with SAD

    Plans for Hadronic Structure Studies at J-PARC

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    Hadron-physics projects at J-PARC are explained. The J-PARC is the most-intense hadron-beam facility in the multi-GeV high-energy region. By using secondary beams of kaons, pions, and others as well as the primary-beam proton, various hadron projects are planned. First, some of approved experiments are introduced on strangeness hadron physics and hadron-mass modifications in nuclear medium. Second, future possibilities are discussed on hadron-structure physics, including structure functions of hadrons, spin physics, and high-energy hadron reactions in nuclear medium. The second part is discussed in more details because this is an article in the hadron-structure session.Comment: 10 pages, LaTeX, 20 eps files, to be published in Journal of Physics: Conference Series (JPCS), Proceedings of the 24th International Nuclear Physics Conference (INPC 2010), Vancouver, Canada, July 4 - 9, 201

    Near-Infrared Adaptive Optics Spectroscopy of Binary Brown Dwarf HD 130948B and C

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    We present near-infrared spectroscopy of low-mass companions in a nearby triple system HD 130948 (Gliese 564, HR 5534). Adaptive optics on the Subaru Telescope allowed spectroscopy of the individual components of the 0".13 binary system. Based on a direct comparison with a series of template spectra, we determined the spectral types of HD 130948B and C to be L4 +- 1. If we take the young age of the primary star into account (0.3-0.8 Gyr), HD 130948B and C most likely are a binary brown dwarf system.Comment: 6 pages, 3 figures, accepted for publication in ApJ Letter

    Selected topics on Hadrons in Nuclei

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    In this talk we report on selected topics on hadrons in nuclei. The first topic is the renormalization of the width of the Λ(1520)\Lambda(1520) in a nuclear medium. This is followed by a short update of the situation of the ω\omega in the medium. The investigation of the properties of Kˉ\bar{K} in the nuclear medium from the study of the (Kflight,p)(K_{flight},p) reaction is also addressed, as well as properties of X,Y,Z charmed and hidden charm resonances in a nuclear medium. Finally we address the novel issue of multimeson states.Comment: Talk at the International Nuclear Physics Conference, Vancouver, July 201

    Preliminary Results from Recent Measurements of the Antiprotonic Helium Hyperfine Structure

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    We report on preliminary results from a systematic study of the hyperfine (HF) structure of antiprotonic helium. This precise measurement which was commenced in 2006, has now been completed. Our initial analysis shows no apparent density or power dependence and therefore the results can be averaged. The statistical error of the observable M1 transitions is a factor of 60 smaller than that of three body quantum electrodynamic (QED) calculations, while their difference has been resolved to a precision comparable to theory (a factor of 10 better than our first measurement). This difference is sensitive to the antiproton magnetic moment and agreement between theory and experiment would lead to an increased precision of this parameter, thus providing a test of CPT invariance.Comment: 6 pages, 4 figure
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