Does participation in productive associations signal trust and creditworthiness ? evidence for Nicaragua

This article studies the extent to which participation in productive associations in Nicaragua contributes to increase individuals'access to social programs and credit services. By participating in productive associations, individuals give a good signal to firms and are rewarded with better transactions and more access to the services they provide, ceteris paribus. Estimates using 2005 data indicate that households that participate in productive associations display higher access to credit and to social programs that promote investment. Additionally, participation in productive associations is weakly associated to more favorable credit outcomes among those households that receive loans, such as lower interest rates and a lower probability of wanting more credit than what was accessible to them.Access to Finance,,Corporate Law,Labor Policies,Debt Markets

Decoherence induced by an interacting spin environment in the transition from integrability to chaos

We investigate the decoherence properties of a central system composed of two spins 1/2 in contact with a spin bath. The dynamical regime of the bath ranges from a fully integrable integrable limit to complete chaoticity. We show that the dynamical regime of the bath determines the efficiency of the decoherence process. For perturbative regimes, the integrable limit provides stronger decoherence, while in the strong coupling regime the chaotic limit becomes more efficient. We also show that the decoherence time behaves in a similar way. On the contrary, the rate of decay of magnitudes like linear entropy or fidelity does not depend on the dynamical regime of the bath. We interpret the latter results as due to a comparable complexity of the Hamiltonian for both the integrable and the fully chaotic limits.Comment: Submitted to Phys. Rev.

Vevacious: A Tool For Finding The Global Minima Of One-Loop Effective Potentials With Many Scalars

Several extensions of the Standard Model of particle physics contain additional scalars implying a more complex scalar potential compared to that of the Standard Model. In general these potentials allow for charge and/or color breaking minima besides the desired one with correctly broken SU(2)_L times U(1)_Y . Even if one assumes that a metastable local minimum is realized, one has to ensure that its lifetime exceeds that of our universe. We introduce a new program called Vevacious which takes a generic expression for a one-loop effective potential energy function and finds all the tree-level extrema, which are then used as the starting points for gradient-based minimization of the one-loop effective potential. The tunneling time from a given input vacuum to the deepest minimum, if different from the input vacuum, can be calculated. The parameter points are given as files in the SLHA format (though is not restricted to supersymmetric models), and new model files can be easily generated automatically by the Mathematica package SARAH. This code uses HOM4PS2 to find all the minima of the tree-level potential, PyMinuit to follow gradients to the minima of the one-loop potential, and CosmoTransitions to calculate tunneling times.Comment: 44 pages, 1 figure, manual for publicly available software, v2 corresponds to version accepted for publication in EPJC [clearer explanation of scale dependence and region of validity, explicit mention that SLHA files should have blocks matching those expected by model files, updated references