Unresolved Unidentified Source Contribution to the Gamma-ray Background

The large majority of EGRET point sources remain without an identified low-energy counterpart, and a large fraction of these sources are most likely extragalactic. Whatever the nature of the extragalactic EGRET unidentified sources, faint unresolved objects of the same class must have a contribution to the diffuse extragalactic gamma-ray background (EGRB). Understanding this component of the EGRB, along with other guaranteed contributions from known sources, is essential if we are to use this emission to constrain exotic high-energy physics. Here, we follow an empirical approach to estimate whether a potential contribution of unidentified sources to the EGRB is likely to be important, and we find that it is. Additionally, we show how upcoming GLAST observations of EGRET unidentified sources, as well as of their fainter counterparts, can be combined with GLAST observations of the Galactic and extragalactic diffuse backgrounds to shed light on the nature of the EGRET unidentified sources even without any positional association of such sources with low-energy counterparts.Comment: 11 pages, 5 figures, submitted to Ap

Large Scale Anisotropy of Cosmic Rays and Directional Neutrino Signals from Galactic Sources

We investigate the neutrino - cosmic ray connection for sources in the Galaxy in terms of two observables: the shape of the energy spectrum and the distribution of arrival directions. We also study the associated gamma ray emission from these sources.Comment: Proceedings of the 2nd Cosmic Ray Anisotropy Workshop, 26-28 September 2013, Madison, Wisconsin. To appear in IOP Conference Serie

Physics with Cosmic Neutrinos, PeV to ZeV

We begin with a brief overview of highest-energy cosmic ray data, and the experiments which will perform neutrino astronomy. We then discuss two particle physics aspects of neutrinos. They are possible long-lifetime decay of the neutrino, and a measurement of the neutrino-nucleon cross-section at a CMS energy orders of magnitude beyond what can be achieved with terrestrial accelerators. Measurement of an anomalously large neutrino cross-section would indicate new physics (e.g. low string-scale, extra dimensions, precocious unification), while a smaller than expected cross-section would reveal an aspect of QCD evolution. We then discuss aspects of neutrino-primary models for the extreme-energy (EE) cosmic ray data. Primary neutrinos in extant data are motivated by the directional clustering at EE reported by the AGASA experiment. We discuss the impact of the strongly-interacting neutrino hypothesis on lower-energy physics via dispersion relations, the statistical significance of AGASA directional clustering, and the possible relevance of the Z-burst mechanism for existing EE cosmic ray data.Comment: 19 pages including 6 figures, Proc. YITP "Neutrinos" Oct. 200

Curvature energy effects on strange quark matter nucleation at finite density

We consider the effects of the curvature energy term on thermal strange quark matter nucleation in dense neutron matter. Lower bounds on the temperature at which this process can take place are given and compared to those without the curvature term.Comment: PlainTex, 6 pp., IAG-USP Rep.5

Equation of State for Helium-4 from Microphysics

We compute the free energy of helium-4 near the lambda transition based on an exact renormalization-group equation. An approximate solution permits the determination of universal and nonuniversal thermodynamic properties starting from the microphysics of the two-particle interactions. The method does not suffer from infrared divergences. The critical chemical potential agrees with experiment. This supports a specific formulation of the functional integral that we have proposed recently. Our results for the equation of state reproduce the observed qualitative behavior. Despite certain quantitative shortcomings of our approximation, this demonstrates that ab initio calculations for collective phenomena become possible by modern renormalization-group methods.Comment: 9 pages, 6 figures, revtex updated version, journal referenc

Nucleation of quark matter bubbles in neutron stars

The thermal nucleation of quark matter bubbles inside neutron stars is examined for various temperatures which the star may realistically encounter during its lifetime. It is found that for a bag constant less than a critical value, a very large part of the star will be converted into the quark phase within a fraction of a second. Depending on the equation of state for neutron star matter and strange quark matter, all or some of the outer parts of the star may subsequently be converted by a slower burning or a detonation.Comment: 13 pages, REVTeX, Phys.Rev.D (in press), IFA 93-32. 5 figures (not included) available upon request from [email protected]