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Cipollone A.,University of Surrey | Barbieri C.,University of Surrey | Navratil P.,TRIUMF Laboratory Particle and Nuclear Physics
Physical Review Letters | Year: 2013

We extend the formalism of self-consistent Green's function theory to include three-body interactions and apply it to isotopic chains around oxygen for the first time. The third-order algebraic diagrammatic construction equations for two-body Hamiltonians can be exploited upon defining system-dependent one- and two-body interactions coming from the three-body force, and, correspondingly, dropping interaction-reducible diagrams. The Koltun sum rule for the total binding energy acquires a correction due to the added three-body interaction. This formalism is then applied to study chiral two- and three-nucleon forces evolved to low momentum cutoffs. The binding energies of nitrogen, oxygen, and fluorine isotopes are reproduced with good accuracy and demonstrate the predictive power of this approach. Leading order three-nucleon forces consistently bring results close to the experiment for all neutron rich isotopes considered and reproduce the correct driplines for oxygen and nitrogen. The formalism introduced also allows us to calculate form factors for nucleon transfer on doubly magic systems. © 2013 American Physical Society. Source


Salas P.F.,University of British Columbia | Herrmann C.,University of British Columbia | Herrmann C.,TRIUMF Laboratory Particle and Nuclear Physics | Orvig C.,University of British Columbia
Chemical Reviews | Year: 2013

Malaria is a worldwide neglected infectious disease that, despite decades of research invested in its prevention and treatment, remains one of the main causes of mortality and morbidity in the world. As reported by the World Health Organization (WHO) in 2011, 3.3 billion people were at risk of malaria, mainly in the 106 malaria-endemic countries located in the tropical and subtropical zones of the globe. Malaria is preventable through methods of malaria vector control. The two most important vector control methods recommended by the WHO are long-lasting insecticide-treated mosquito nets (LLIN) and indoor residual spraying (IRS). Indoor residual spraying (IRS) with WHO-approved chemicals consists of application of residual insecticides to the inner surfaces of dwellings. Of all factors that have contributed to the recrudescence of malaria in the last 50 years, increasing antimalarial drug resistance is probably the major contributor. This phenomenon, which rapidly depleted the therapies available to fight malaria, has led to intensive research carried out for decades that produced a large pool of antimalarial drugs. Source


Navratil P.,TRIUMF Laboratory Particle and Nuclear Physics | Navratil P.,Lawrence Livermore National Laboratory | Quaglioni S.,Lawrence Livermore National Laboratory
Physical Review Letters | Year: 2012

We apply the ab initio no-core shell model combined with the resonating-group method approach to calculate the cross sections of the H3(d,n)He4 and He3(d,p)He4 fusion reactions. These are important reactions for the big bang nucleosynthesis and the future of energy generation on Earth. Starting from a selected similarity-transformed chiral nucleon-nucleon interaction that accurately describes two-nucleon data, we performed many-body calculations that predict the S factor of both reactions. Virtual three-body breakup effects are obtained by including excited pseudostates of the deuteron in the calculation. Our results are in satisfactory agreement with experimental data and pave the way for microscopic investigations of polarization and electron-screening effects, of the H3(d,γn)He4 bremsstrahlung and other reactions relevant to fusion research. © 2012 American Physical Society. Source


Kumar A.,TRIUMF Laboratory Particle and Nuclear Physics | Tulin S.,University of Michigan
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We propose a simple model where dark matter (DM) carries top flavor and couples to the Standard Model through the top quark within a framework of minimal flavor violation. Top-flavored DM can explain the anomalous top forward-backward asymmetry observed at the Tevatron, while remaining consistent with other top observables at colliders. By virtue of its large coupling to the top, DM acquires a sizable loop coupling to the Z boson, and the relic density is set by annihilation through the Z. We also discuss constraints from current direct detection searches, emphasizing the role of spin-dependent searches to probe this scenario. © 2013 American Physical Society. Source


Morris G.D.,TRIUMF Laboratory Particle and Nuclear Physics
Hyperfine Interactions | Year: 2014

The β-NMR facility at ISAC is constructed specifically for experiments in condensed matter physics with radioactive ion beams. Using co-linear optical pumping, a 8Li+ ion beam having a large nuclear spin polarisation and low energy (nominally 30 keV) can be generated. When implanted into materials these ions penetrate to shallow depths comparable to length scales of interest in the physics of surfaces and interfaces between materials. Such low-energy ions can be decelerated with simple electrostatic optics to enable depth-resolved studies of near-surface phenomena over the range of about 2-200 nm. Since the β-NMR signal is extracted from the asymmetry intrinsic to beta-decay and therefore monitors the polarisation of the radioactive probe nuclear magnetic moments, this technique is fundamentally a probe of local magnetism. More generally though, any phenomena which affects the polarisation of the implanted spins by, for example, a change in resonance frequency, line width or relaxation rate can be studied. The β-NMR program at ISAC currently supports a number of experiments in magnetism and superconductivity as well as novel ultra-thin heterostructures exhibiting properties that cannot occur in bulk materials. The general purpose zero/low field and high field spectrometers are configured to perform CW and pulsed RF nuclear magnetic resonance and spin relaxation experiments over a range of temperatures (3-300 K) and magnetic fields (0-9 T). © 2013 Springer Science+Business Media Dordrecht. Source

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