R Symmetry Breaking Versus Supersymmetry Breaking

We point out a connection between R symmetry and \susy\ breaking. We show that the existence of an R symmetry is a necessary condition for \susy\ breaking and a spontaneously broken R symmetry is a sufficient condition provided two conditions are satisfied. These conditions are: {\it genericity}, \ie\ the effective Lagrangian is a generic Lagrangian consistent with the symmetries of the theory (no fine tuning), and {\it calculability}, \ie\ the low energy theory can be described by a supersymmetric Wess-Zumino effective Lagrangian without gauge fields. All known models of dynamical supersymmetry breaking possess such a spontaneously broken R symmetry and therefore contain a potentially troublesome axion. However, we use the fact that genericity is {\it not} a feature of supersymmetric theories, even when nonperturbative renormalization is included, to show that the R symmetry can in many cases be explicitly broken without restoring supersymmetry and so the axion can be given an acceptably large mass.Comment: 20 pages, UCSD/PTH 93-27, RU-93-4

Comportamento inicial de cultivares de Coffea arabica L. com resistência à ferrugem cultivadas na Região de Muzambinho-MG.

O presente trabalho trás os resultados preliminares de um ensaio sobre competição entre cultivares de Coffea arabica L. resistentes à ferrugem, e tem como objetivo avaliar o crescimento, resistência à ferrugem e o potencial de produção de diferentes genótipos cultivados na região de Muzambinho, no sul do estado de Minas Gerais. Para tanto o experimento foi instalado e está sendo conduzido na área experimental da Escola Agrotécnica Federal de Muzambinho (EAFMuz) em Muzambinho ? MG, em parceria com a Fundação MAPA/PROCAFÉ, sediada no município de Varginha ? MG. O experimento consta de um delineamento em blocos ao acaso (DBC), com 4 blocos (4 repetições), com 5 plantas úteis por parcelas. Como tratamento, o experimento conta com 34 diferentes genótipos de Coffea arabica (L.). Os tratos culturais utilizados foram comuns a todos os tratamentos, sendo que não houve controle químico no combate à doença ferrugem. Os resultados preliminares mostram que nenhum genótipo testado apresentou sintomas típicos de ferrugem na folha. Os genótipos Catucaí vermelho 36/6 porte médio precoce cv 365 (3.12), Catucaiaçu Jaguarai e Catucaí amarelo 24/137 Jaguaraí mostraram serem superiores em relação aos demais genótipos, quando se avaliou o diâmetro da copa, diâmetro do caule (tomados a 10 cm do colo) e altura da planta

Modular Cosmology

An exploratory study of the cosmology of moduli in string theory. Moduli are argued to be natural inflaton fields and lead to a robust inflationary cosmology in which inflation takes place at the top of domain walls. The amplitude of microwave background fluctuations constrains the dynamics responsible for inflation to take place at a higher scale than supersymmetry breaking. Models explaining this difference in scales and also preventing the dilaton from running to infinity are proposed. The problem of dilaton domination of the energy density of the universe is not resolved.Comment: harvmac, 37 pages, 3 figures as a separate uuencoded tar fil

Blind test of density-functional-based methods on intermolecular interaction energies

In the past decade, a number of approaches have been developed to fix the failure of (semi) local density-functional theory (DFT) in describing intermolecular interactions. The performance of several such approaches with respect to highly accurate benchmarks is compared here on a set of separation-dependent interaction energies for ten dimers. Since the benchmarks were unknown before the DFT-based results were collected, this comparison constitutes a blind test of these methods