Early texts on Hindu-Arabic calculation

This article describes how the decimal place value system was transmitted from India via the Arabs to the West up to the end of the fifteenth century. The arithmetical work of al-Khw¯arizm¯ı’s, ca. 825, is the oldest Arabic work on Indian arithmetic of which we have detailed knowledge. There is no known Arabic manuscript of this work; our knowledge of it is based on an early reworking of a Latin translation. Until some years ago, only one fragmentary manuscript of this twelfth-century reworking was known (Cambridge, UL, Ii.6.5). Another manuscript that transmits the complete text (New York, Hispanic Society of America, HC 397/726) has made possible a more exact study of al-Khw¯arizm¯ı’s work. This article gives an outline of this manuscript’s contents and discusses some characteristics of its presentation

Massive spin-2 theories

We give an introduction to massive spin-2 theories and the problem of their non-linear completion. We review the Boulware-Deser ghost problem and two ways to circumvent classic no-go theorems. In turn, massive spin-2 theories are not uniquely defined. In the case of truncated theories, we show that the Boulware-Deser ghost may only be avoided if the derivative structure of the theory is not tuned to be Einsteinian.Comment: 14 pages - Invited review for the Central European Journal of Physics, topical issue devoted to "Cosmology and Particle Physics beyond Standard Models". v2: References added, extended discussion on massive gravit

Axion Dark Matter and Planck favor non-minimal couplings to gravity

Constraints on inflationary scenarios and isocurvature perturbations have excluded the simplest and most generic models of dark matter based on QCD axions. Considering non-minimal kinetic couplings of scalar fields to gravity substantially changes this picture. The axion can account for the observed dark matter density avoiding the overproduction of isocurvature fluctuations. Finally, we show that assuming the same non-minimal kinetic coupling to the axion (dark matter) and to the standard model Higgs boson (inflaton) provides a minimal picture of early time cosmology.Comment: 7 pages, 1 figure, revtex, v3: explanations and references added, accepted for publication in Phys.Lett.

Research study on IPS digital controller design

The performance is investigated of the simplified continuous-data model of the Instrument Pointing System (IPS). Although the ultimate objective is to study the digital model of the system, knowledge on the performance of the continuous-data model is important in the sense that the characteristics of the digital system should approach those of the continuous-data system as the sampling period approaches zero