1,437 research outputs found
Constraints on a possible dineutron state from pionless EFT
We investigate the sensitivity of the three-nucleon system to changes in the
neutron-neutron scattering length to next-to-leading order in the pionless
effective field theory, focusing on the the triton-3He binding energy
difference and neutron-deuteron elastic scattering. Due to the appearance of an
electromagnetic three-body counterterm at this order, the triton-3He binding
energy difference remains consistent with the experimental value even for large
positive neutron-neutron scattering lengths while the elastic neutron-deuteron
scattering phase shifts are insensitive. We conclude that a bound dineutron
cannot be excluded to next-to-leading order in pionless EFT.Comment: 11 pages, 5 figure
Low-energy p-d scattering and He-3 in pionless EFT
We calculate low-energy proton--deuteron scattering in the framework of
pionless effective field theory. In the quartet channel, we calculate the
elastic scattering phase shift up to next-to-next-to-leading order in the power
counting. In the doublet channel, we perform a next-to-leading order
calculation. We obtain good agreement with the available phase shift analyses
down to the scattering threshold. The phase shifts in the region of
non-perturbative Coulomb interactions are calculated by using an optimised
integration mesh. Moreover, the Coulomb contribution to the 3He-3H binding
energy difference is evaluated in first order perturbation theory. We comment
on the implications of our results for the power counting of subleading
three-body forces.Comment: 27 pages, 13 figures, typos corrected in Sec. V.A (trinucleon wave
functions
Linear Programming for a Cutting Problem in the Wood Processing Industry – A Case Study
In this paper the authors present a case study from the wood-processing industry. It focuses on a cutting process in which material from stock is cut down in order to provide the items required by the customers in the desired qualities, sizes, and quantities. In particular, two aspects make this cutting process special. Firstly, the cutting process is strongly interdependent with a preceding handling process, which, consequently, cannot be planned independently. Secondly, if the trim loss is of a certain minimum size, it can be returned into stock and used as input to subsequent cutting processes. In order to reduce the cost of the cutting process, a decision support tool has been developed which incorporates a linear programming model as a central feature. The model is described in detail, and experience from the application of the tool is reported.one-dimensional cutting, linear programming, wood-processing industry
Conditional Transition Systems with Upgrades
We introduce a variant of transition systems, where activation of transitions
depends on conditions of the environment and upgrades during runtime
potentially create additional transitions. Using a cornerstone result in
lattice theory, we show that such transition systems can be modelled in two
ways: as conditional transition systems (CTS) with a partial order on
conditions, or as lattice transition systems (LaTS), where transitions are
labelled with the elements from a distributive lattice. We define equivalent
notions of bisimilarity for both variants and characterise them via a
bisimulation game.
We explain how conditional transition systems are related to featured
transition systems for the modelling of software product lines. Furthermore, we
show how to compute bisimilarity symbolically via BDDs by defining an operation
on BDDs that approximates an element of a Boolean algebra into a lattice. We
have implemented our procedure and provide runtime results
Volume Dependence of Bound States with Angular Momentum
We derive general results for the mass shift of bound states with angular
momentum l >= 1 in a finite periodic volume. Our results have direct
applications to lattice simulations of hadronic molecules as well as atomic
nuclei. While the binding of S-wave bound states increases at finite volume, we
show that the binding of P-wave bound states decreases. The mass shift for
D-wave bound states as well as higher partial waves depends on the
representation of the cubic rotation group. Nevertheless, the
multiplet-averaged mass shift for any angular momentum l can be expressed in a
simple form, and the sign of the shift alternates for even and odd l. We verify
our analytical results with explicit numerical calculations. We also show
numerically that similar volume corrections appear in three-body bound states.Comment: 4 pages, 3 figures, final versio
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