The Scientific Life Of John Bahcall

This article follows the scientific life of John Norris Bahcall, including his tenacious pursuit of the solar neutrino problem, his contributions to our understanding of galaxies, quasars, and their emissions, and his leadership of and advocacy for astronomy and astrophysics.Comment: Prefactory for Annual Reviews of Nuclear and Particle Science; 23 pages, 6 figure

Dark Matter from Minimal Flavor Violation

We consider theories of flavored dark matter, in which the dark matter particle is part of a multiplet transforming nontrivially under the flavor group of the Standard Model in a manner consistent with the principle of Minimal Flavor Violation (MFV). MFV automatically leads to the stability of the lightest state for a large number of flavor multiplets. If neutral, this particle is an excellent dark matter candidate. Furthermore, MFV implies specific patterns of mass splittings among the flavors of dark matter and governs the structure of the couplings between dark matter and ordinary particles, leading to a rich and predictive cosmology and phenomenology. We present an illustrative phenomenological study of an effective theory of a flavor SU(3)_Q triplet, gauge singlet scalar.Comment: 10 pages, 2 figures; v2: references added, minor changes to collider analysis, conclusions unchange

Two-loop leading color corrections to heavy-quark pair production in the gluon fusion channel

We evaluate the two-loop QCD diagrams contributing to the leading color coefficient of the heavy-quark pair production cross section in the gluon fusion channel. We obtain an analytic expression, which is valid for any value of the Mandelstam invariants s and t and of the heavy-quark mass m. Our findings agree with previous analytic results in the small-mass limit and with recent results for the coefficients of the IR poles