10,615 research outputs found

    Production rates for hadrons, pentaquarks Θ+\Theta ^+ and Θ++\Theta ^{*++}, and di-baryon (ΩΩ)0+(\Omega\Omega)_{0^{+}} in relativistic heavy ion collisions by a quark combination model

    Full text link
    The hadron production in relativistic heavy ion collisions is well described by the quark combination model. The mixed ratios for various hadrons and the transverse momentum spectra for long-life hadrons are predicted and agree with recent RHIC data. The production rates for the pentaquarks Θ+\Theta ^+, Θ++\Theta ^{*++} and the di-baryon (ΩΩ)0+(\Omega\Omega)_{0^{+}} are estimated, neglecting the effect from the transition amplitude for constituent quarks to form an exotic state.Comment: The difference between our model and other combination models is clarified. The scaled transverse momentum spectra for pions, kaons and protoms at both 130 AGeV and 200 AGeV are given, replacing the previous results in transverse momentum spectr

    X-ray Timing Observations of PSR J1930+1852 in the Crab-like SNR G54.1+0.3

    Get PDF
    We present new X-ray timing and spectral observations of PSR J1930+1852, the young energetic pulsar at the center of the non-thermal supernova remnant G54.1+0.3. Using data obtained with the Rossi X-ray Timing Explorer and Chandra X-ray observatories we have derived an updated timing ephemeris of the 136 ms pulsar spanning 6 years. During this interval, however, the period evolution shows significant variability from the best fit constant spin-down rate of P˙=7.5112(6)×1013\dot P = 7.5112(6) \times 10^{-13} s s1^{-1}, suggesting strong timing noise and/or glitch activity. The X-ray emission is highly pulsed (71±571\pm5% modulation) and is characterized by an asymmetric, broad profile (70\sim 70% duty cycle) which is nearly twice the radio width. The spectrum of the pulsed emission is well fitted with an absorbed power law of photon index Γ=1.2±0.2\Gamma = 1.2\pm0.2; this is marginally harder than that of the unpulsed component. The total 2-10 keV flux of the pulsar is 1.7×10121.7 \times 10^{-12} erg cm2^{-2} s1^{-1}. These results confirm PSR J1930+1852 as a typical Crab-like pulsar.Comment: 14 pages with 7 figures included, accepted to Ap

    Parallel processing of semantics and phonology in spoken production:Evidence from blocked cyclic picture naming and EEG

    Get PDF
    Spoken language production involves lexical-semantic access and phonological encoding. A theoretically important question concerns the relative time course of these two cognitive processes. The predominant view has been that semantic and phonological codes are accessed in successive stages. However, recent evidence seems difficult to reconcile with a sequential view but rather suggests that both types of codes are accessed in parallel. Here, we used ERPs combined with the "blocked cyclic naming paradigm" in which items overlapped either semantically or phonologically. Behaviorally, both semantic and phonological overlap caused interference relative to unrelated baseline conditions. Crucially, ERP data demonstrated that the semantic and phonological effects emerged at a similar latency (similar to 180 msec after picture onset) and within a similar time window (180-380 msec). These findings suggest that access to phonological information takes place at a relatively early stage during spoken planning, largely in parallel with semantic processing
    corecore