1,378 research outputs found
Central Speed of Sound, Trace Anomaly and Observables of Neutron Stars from Perturbative Analyses of Scaled TOV Equations
The central speed of sound (SS) measures the stiffness of the Equation of
State (EOS) of superdense neutron star (NS) matter. Its variations with density
and radial coordinate in NSs in conventional analyses often suffer from
uncertainties of the specific nuclear EOSs used. Using the central SS and NS
mass/radius scaling obtained from solving perturbatively the scaled
Tolman-Oppenheimer-Volkoff (TOV) equations, we study the variations of SS,
trace anomaly and several closely related properties of NSs in an EOS-model
independent manner. We find that the SS increases with the reduced central
pressure (scaled
by the central energy density ), and the conformal bound
for SS is violated for NSs with masses higher than about 1.9M. The
ratio is upper bounded as around
the centers of stable NSs. We demonstrate that it is an intrinsic property of
strong-field gravity and is more relevant than the perturbative QCD bound on
it. While a sharp phase transition at high densities characterized by a sudden
vanishing of SS in cores of massive NSs are basically excluded, the probability
for a continuous crossover signaled by a peaked radial profile of SS is found
to be enhanced as decreases, implying it likely happens
near the centers of massive NSs. Moreover, a new and more stringent causality
boundary as for
NS M-R curve is found to be excellently consistent with observational data on
NS masses and radii. Furthermore, new constraints on the ultimate energy
density and pressure allowed in NSs before collapsing into black holes are
obtained and compared with earlier predictions in the literature.Comment: 23 page
Morphology of the immature stages of Panorpa qinlingensis (Mecoptera: Panorpidae) with notes on its biology
The scorpionfly Panorpa qinlingensis Chou & Ran is described and illustrated in detail for its immature stages, including egg, larva, and pupa. The egg is oval with chorion decorated with irregular polygonal network. The larva is eruciform and peripneustic, bearing eight pairs of abdominal prolegs. A pair of prominent compound eyes are present on head. The first instar larva differs from later instars in possessing a prominent egg burster on frons and with clavate setae. The pupa is exarate and decticous, taking the shape of the adults. The scorpionfly is bivoltine, overwintering as prepupal stage in the soil. The durations of the egg, larval, and pupal stages are 5β9 d, 19β27 d, and 8β18 d respectively for the first generation. Adults emerge from mid May to early June and from late July to mid August in the Micang Mountain, central China
Study on the mechanism of open-flavor strong decays
The open-flavor strong decays are studied based on the interaction of
potential quark model. The decay process is related to the s-channel
contribution of the same scalar confinment and one-gluon-exchange(OGE)
interaction in the quark model. After we adopt the prescription of massive
gluons in time-like region from the lattice calculation, the approximation of
four-fermion interaction is applied. The numerical calculation is performed to
the meson decays in , , light flavor sector. The analysis of the
ratios of and show
that the scalar interaction should be dominant in the open-flavor decays
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