Naturalness

Abstract: A properly called “naturalness” is imposed on gauge theories It is an order-of-magnitude restriction that must hold at all energy scales μ To construct models with complete naturalness for elementary particles one needs more types of confining gauge theories besides quantum chromodynamics We propose a search program for models with improved naturalness and concentrate on the possibility that presently elementary fermions can be considered as composite Chiral symmetry must then be responsible for the masslessness of these fermions Thus we search for QCD-like models where chiral symmetry is not or only partly broken spontaneously They are restricted by index relations that often cannot be satisfied by other than unphysical fractional indices This difficulty made the author’s own search unsuccessful so far As a by-product we find yet another reason why in ordinary QCD chiral symmetry must be broken spontaneously

Abstract: Phil O'Keefe, Ken Westgate and Ben Wisner argue the case that disasters are more a consequence of socio-economic than natural factors.

Abstract: Natural languages like English are rich, complex, and powerful. The highly creative and graceful use of languages like English and Tamil, by masters like Shakespeare and Avvaiyar, can certainly delight and inspire. But in practice, given cognitive constraints and the exigencies of daily life, most human utterances are far simpler and much more repetitive and predictable. In fact, these utterances can be very usefully modeled using modern statistical methods. This fact has led to the phenomenal success of statistical approaches to speech recognition, natural language translation, question-answering, and text mining and comprehension. We begin with the conjecture that most software is also natural, in the sense that it is created by humans at work, with all the attendant constraints and limitations — and thus, like natural language, it is also likely to be repetitive and predictable. We then proceed to ask whether a) code can be usefully modeled by statistical language models and b) such models can be leveraged to support software engineers. Using the widely adopted n-gram model, we provide empirical evidence supportive of a positive answer to both these questions. We show that code is also very repetitive, and in fact even more so than natural languages. As an example use of the model, we have developed a simple code completion engine for Java that, despite its simplicity, already improves Eclipse's built-in completion capability. We conclude the paper by laying out a vision for future research in this area.

Abstract: Constraints from precision electroweak measurements reveal no evidence for new physics up to 5–7 TeV, whereas naturalness requires new particles at around 1 TeV to address the stability of the electroweak scale. We show that this ``little hierarchy problem'' can be cured by introducing a symmetry for new particles at the TeV scale. As an example, we construct a little Higgs model with this new symmetry, dubbed T-parity, which naturally solves the little hierarchy problem and, at the same time, stabilize the electroweak scale up to 10 TeV. The model has many important phenomenological consequences, including consistency with the precision data without any fine-tuning, a stable weakly-interacting particle as the dark matter candidate, as well as collider signals completely different from existing little Higgs models, but rather similar to the supersymmetric theories with conserved R-parity.