7 research outputs found
Hadronic Parity Violation: a New View through the Looking Glass
Studies of the strangeness changing hadronic weak interaction have produced a
number of puzzles that have so far evaded a complete explanation within the
Standard Model. Their origin may lie either in dynamics peculiar to weak
interactions involving strange quarks or in more general aspects of the
interplay between strong and weak interactions. In principle, studies of the
strangeness conserving hadronic weak interaction using parity violating
hadronic and nuclear observables provide a complementary window on this
question. However, progress in this direction has been hampered by the lack of
a suitable theoretical framework for interpreting hadronic parity violation
measurements in a model-independent way. Recent work involving effective field
theory ideas has led to the formulation of such a framework while motivating
the development of a number of new hadronic parity violation experiments in
few-body systems. In this article, we review these recent developments and
discuss the prospects and opportunities for further experimental and
theoretical progress.Comment: Manuscript submitted to Annual Reviews of Nuclear and Particle
Scienc
X-ray Reflectivity Studies of the Surface Structure of Liquid Metals
Extensive theoretical predictions of atomic layering at the surfaces of liquid metals have remained unconfirmed due to the limited range of wave vector transfer qz that has been previously measured. We report here on X-ray reflectivity studies from the surfaces of liquid mercury to qz greater-than or equivalent to 2.8 Å−1, and gallium to qz greater-than or equivalent to 3.0 Å−1, that show peaks which clearly demonstrate atomic layering with spacing on the order of the atomic diameter. The exponential decay of layer penetration into the bulk for Ga (6.5 Å) is larger than for Hg (3–3.5 Å). The prominent features of the layering remain unchanged under self-assembled monolayers of thiols. The Ga layering shows an unexpected strong temperature dependence. Differences between the reflectivity from Ga and Hg at small qz indicate fundamental differences in the surface structure for these two liquid metals.Engineering and Applied Science