2,322 research outputs found
Resolvable Mendelsohn designs and finite Frobenius groups
We prove the existence and give constructions of a -fold perfect
resolvable -Mendelsohn design for any integers with such that there exists a finite Frobenius group whose kernel
has order and whose complement contains an element of order ,
where is the least prime factor of . Such a design admits as a group of automorphisms and is perfect when is a
prime. As an application we prove that for any integer in prime factorization, and any prime dividing
for , there exists a resolvable perfect -Mendelsohn design that admits a Frobenius group as a group of
automorphisms. We also prove that, if is even and divides for
, then there are at least resolvable -Mendelsohn designs that admit a Frobenius group as a group of
automorphisms, where is Euler's totient function.Comment: Final versio
Dynamics of the quantum dimer model on the triangular lattice: Soft modes and local resonating valence-bond correlations
We report on an exhaustive investigation of the dynamical dimer-dimer
correlations in imaginary time for the quantum dimer model on the triangular
lattice using the Green's function Monte Carlo method. We show in particular
that soft modes develop upon reducing the dimer-dimer repulsion, indicating the
presence of a second-order phase transition into an ordered phase with broken
translational symmetry. We further investigate the nature of this ordered
phase, for which a 12-site unit cell has been previously proposed, with the
surprising result that significant Bragg peaks are only present at two of the
three high-symmetry points consistent with this unit cell. We attribute the
absence of a detectable peak to its small magnitude due to the nearly uniform
internal structure of the 12-site crystal cell.Comment: 6 pages, 8 figure
Diagrammatic Monte Carlo algorithm for the resonant Fermi gas
We provide a description of a diagrammatic Monte Carlo algorithm for the
resonant Fermi gas in the normal phase. Details are given on diagrammatic
framework, Monte Carlo moves, and incorporation of ultraviolet asymptotics.
Apart from the self-consistent bold scheme, we also describe a
non-self-consistent scheme, for which the ultraviolet treatment is more
involved.Comment: Revised and extended versio
Ground-state phase diagram of the three-band Hubbard model from density matrix embedding theory
We determine the ground-state phase diagram of the three-band Hubbard model across a range of model parameters using density matrix embedding theory. We study the atomic-scale nature of the antiferromagnetic (AFM) and superconducting (SC) orders, explicitly including the oxygen degrees of freedom. All parametrizations of the model display AFM and SC phases, but the decay of AFM order with doping is too slow compared to the experimental phase diagram, and further, coexistence of AFM and SC orders occurs in all parameter sets. The local magnetic moment localizes entirely at the copper sites. The magnetic phase diagram is particularly sensitive to Î_(pd) and t_(pp), and existing estimates of the charge transfer gap Î_(pd) appear too large in so-called minimal model parametrizations. The electron-doped side of the phase diagram is qualitatively distinct from the hole-doped side and we find an unusual two-peak structure in the SC in the full model parametrization. Examining the SC order at the atomic scale, within the larger scale d_(xÂČâyÂČ)-wave SC pairing order between Cu-Cu and O-O, we also observe a local p_(x(y)) [or d_(xz(yz))] symmetry modulation of the pair density on the Cu-O bonds. Our work highlights some of the features that arise in a three-band versus one-band picture, the role of the oxygen degrees of freedom in new kinds of atomic-scale SC orders, and the necessity of re-evaluating current parametrizations of the three-band Hubbard model
Football goal scoring detection system
The project objective is to simulate Goal Line Technology (GLT) in a football goal. For this, an electronic system is designed and built which is able to detect when the ball has crossed the goal line. This system also can differentiate if the object which has crossed the goal line is the ball or the goalkeeper or whatever it may be. Infrared technology is used in order to develop the GLT, specifically a kind of infrared light curtain. To carry out this technology is necessary to define the basic operation of this. IR-Leds and IR-Photodiodes are used as emitters and receivers, respectively. They make a kind of infrared light curtain because unlike a proper curtain, in this case, all of the emitters are not switched on at the same time, only a pair of emitter-receiver are switched on, then they are switched off and then the following pair of emitter-receiver are switched on, doing a scan along of the emitters-receivers pairs columns. Another requirement of GLT is using an alarm device; a red-led is switched on in the case of detecting that the ball has crossed the goal line. On the other hand, if another thing crosses the goal line, no notification is showed. This system is designed and built for a goal, a ball and a player in scale; it can be applicable in real life and also shows another way of how the âghost goalsâ can be solved. This system can help the referee to clarify controversial situations in football which means an improvement of this sport and a forward step in order to make this game fairer
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