We show that a hybrid (nuclear+quark matter) star can have a mass-radius relationship very similar to that predicted for a star made of purely nucleonic matter. We show this for a generic parameterization of the quark matter equation of state and also for an MIT bag model, each including a phenomenological correction based on gluonic corrections to the equation of state. We obtain hybrid stars as heavy as 2 M for reasonable values of the bag model parameters. For nuclear matter, we use the equation of state calculated by Akmal and coworkers using many-body techniques. Both mixed and homogeneous phases of nuclear and quark matter are considered.

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A unified description of single-pion photoproduction data, together with pion-and etahadroproduction data, has been achieved in a Chew-Mandelstam parametrization which is consistent with unitarity at the two-body level. Energy-dependent and single-energy partial wave analyses of pion photoproduction data have been performed and compared to previous SAID fits and multipoles from the Mainz and Bonn-Gatchina groups.

We calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN) by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a multi-energy group Boltzmann neutrino energy transport scheme. The modular structure of our code provides the ability to dissect the relative contributions of each process responsible for evolving the dynamics of the early universe in the absence of neutrino flavor oscillations. Such an approach allows a detailed accounting of the evolution of the νe,νe, νµ,νµ, ντ ,ντ energy distribution functions alongside and self-consistently with the nuclear reactions and entropy/heat generation and flow between the neutrino and photon/electron/positron/baryon plasma components. This calculation reveals nonlinear feedback in the time evolution of neutrino distribution functions and plasma thermodynamic conditions (e.g., electron-positron pair densities), with implications for: the phasing between scale factor and plasma temperature; the neutron-to-proton ratio; light-element abundance histories; and the cosmological parameter N eff . We find that our approach of following the time development of neutrino spectral distortions and concomitant entropy production and extraction from the plasma results in changes in the computed value of the BBN deuterium yield. For example, for particular implementations of quantum corrections in plasma thermodynamics, our calculations show a 0.4% increase in deuterium. These changes are potentially significant in the context of anticipated improvements in obversational and nuclear physics uncertainties.PACS numbers: 95.85.Ry,14.60.Lm,26.35.+c,98.70.Vc

This article describes a cavity ring-down spectrometer (CaRDS) specifically designed and constructed for installation on the NOAA WP-3D Orion (P-3) aircraft for sensitive, rapid in situ measurement of NO3 and N2O5. While similar to our previously described CaRDS instrument, this instrument has significant improvements in the signal-to-noise ratio, the time resolution, and in overall size and weight. Additionally, the instrument utilizes a custom-built, automated filter changer that was designed and constructed to meet the requirement for removal of particulate matter in the airflow while allowing fully autonomous instrument operation. The CaRDS instrument has a laboratory detection sensitivity of 4×10−11cm−1 in absorbance or 0.1pptv (pptv denotes parts per trillion volume) of NO3 in a 1s average, although the typical detection sensitivities encountered in the field were 0.5pptv for NO3 and 1pptv for N2O5. The instrument accuracy is 25% for NO3 and 20%–40% for N2O5, limited mainly by the uncertainty in the inlet transmission. The instrument has been deployed on the P-3 aircraft as part of a major field campaign in the summer of 2004 and during several ground and tower deployments near Boulder, CO.