69 research outputs found
Leptogenesis in SO(10) models with a left-right symmetric seesaw mechanism
We study leptogenesis in supersymmetric SO(10) models with a left-right
symmetric seesaw mechanism, including flavour effects and the contribution of
the next-to-lightest right-handed neutrino. Assuming M_D = M_u and hierarchical
light neutrino masses, we find that successful leptogenesis is possible for 4
out of the 8 right-handed neutrino mass spectra that are compatible with the
observed neutrino data. An accurate description of charged fermion masses
appears to be an important ingredient in the analysis.Comment: Submitted for the SUSY07 proceedings, 4 pages, 9 figure
A bi-objective model for the single-machine scheduling problem with rejection cost and total tardiness minimization
We study the problem of scheduling jobs on a single machine with a rejection possibility, concurrently minimizing the total tardiness of the scheduled jobs and the total cost of the rejected ones. The model we consider is fully bi-objective, i.e. its aim is to enumerate the Pareto front. We tackle the problem both with and without the presence of hard deadlines. For the case without deadlines, we provide a pseudo-polynomial time algorithm, based on the dynamic program of Steiner and Zhang (2011), thereby proving that the problem is weakly NP-hard. For the case with deadlines, we propose a branch-and-bound algorithm and prove its efficiency by comparing it to an \u3b5-constrained approach on benchmark instances based on those proposed in the literature on similar problems
Polynomial and pseudo-polynomial time algorithms for different classes of the Distance Critical Node Problem
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