16,200 research outputs found
Dynamical Supersymmetry Breaking at Low Energies
Conventional approaches to supersymmetric model building suffer from several
naturalness problems: they do not explain the large hierarchy between the weak
scale and the Planck mass, and they require fine tuning to avoid large flavor
changing neutral currents and particle electric dipole moments. The existence
of models with dynamical supersymmetry breaking, which can explain the
hierarchy, has been known for some time, but efforts to build such models have
suffered from unwanted axions and difficulties with asymptotic freedom. In this
paper, we describe an approach to model building with supersymmetry broken at
comparatively low energies which solves these problems, and give a realistic
example.Comment: (23 pages), phyzzx, 8 figures not included, SCIPP 93/03, UCSD/PTH
93-05. Several references have been adde
Using an interactive whiteboard and a computer-programming tool to support the development of the key competencies in the New Zealand curriculum
Does childrenâs use of the software Scratch provide potential for the enhancement of key competencies as they work in pairs at the interactive whiteboard (IWB)? This article looks at how children using Scratch collaborated and managed their projects as they set about designing, constructing, testing and evaluating a game for others to play, a task that provided a sustained challenge over six weeks and beyond.
The findings showed that the key competencies of participating, contributing, and relating to others were enhanced by the collaborative use of Scratch at the IWB, and that creative and conceptual thinking processes were sustained. Children became increasingly adept at using Scratch, and some children, previously thought to have poor social skills, began to articulate their understandings to others. While a guiding and scaffolding role was evident in teachersâ actions, close monitoring of group progress and direct input from teachers is required to keep the challenge high but achievable, and to extend childrenâs knowledge and thinking as they use Scratch at the IWB
Social and emotional aspects of learning (SEAL) programme in secondary schools : national evaluation
Constraints on Theories With Large Extra Dimensions
Recently, a number of authors have challenged the conventional assumption
that the string scale, Planck mass, and unification scale are roughly
comparable. It has been suggested that the string scale could be as low as a
TeV. In this note, we explore constraints on these scenarios. We argue that the
most plausible cases have a fundamental scale of at least 10 TeV and five
dimensions of inverse size 10 MeV. We show that a radial dilaton mass in the
range of proposed millimeter scale gravitational arises naturally in these
scenarios. Most other scenarios require huge values of flux and may not be
realizable in M Theory. Existing precision experiments put a conservative lower
bound of 6-10 TeV on the fundamental energy scale. We note that large
dimensions with bulk supersymmetry might be a natural framework for
quintessence, and make some other tentative remarks about cosmology.Comment: 31 pp. latex. Minor changes, ref. problems fixe
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