2,443 research outputs found
The Muon Anomalous Magnetic Moment in the Reduced Minimal 3-3-1 Model
We study the muon anomalous magnetic moment in the context of
the reduced minimal 3-3-1 model recently proposed in the literature. In
particular, its spectrum contains a doubly charged scalar () and
gauge boson (), new singly charged vectors () and a
boson, each of which might give a sizeable contribution to the
. We compute the 1-loop contributions from all these new particles
to the . We conclude that the doubly charged vector boson provides
the dominant contribution, and by comparing our results with the experimental
constraints we derive an expected value for the scale of symmetry breaking TeV. We also note that, if the
discrepancy in the anomalous moment is resolved in the future without this
model then the constraints will tighten to requiring TeV with
current precision, and will entirely rule out the model if the expected
precision is achieved by the future experiment at Fermilab.Comment: 19 pages, 4 figure
Quantum noise induced entanglement and chaos in the dissipative quantum model of brain
We discuss some features of the dissipative quantum model of brain in the
frame of the formalism of quantum dissipation. Such a formalism is based on the
doubling of the system degrees of freedom. We show that the doubled modes
account for the quantum noise in the fluctuating random force in the
system-environment coupling. Remarkably, such a noise manifests itself through
the coherent structure of the system ground state. The entanglement of the
system modes with the doubled modes is shown to be permanent in the infinite
volume limit. In such a limit the trajectories in the memory space are
classical chaotic trajectories.Comment: 14 page
A 331 WIMPy Dark Radiation Model
Recent observations suggest that the number of relativistic degrees of
freedom in the early universe might exceed what is predicted in the standard
cosmological model. If even a small, percent-level fraction of dark matter
particles are produced relativistically, they could mimic the effect of an
extra realistic species at matter-radiation equality while obeying BBN, CMB and
Structure Formation bounds. We show that this scenario is quite naturally
realized with a weak-scale dark matter particle and a high-scale ``mother''
particle within a well motivated 3-3-1 gauge model, which is particularly
interesting for being consistent with electroweak precision measurements, with
recent LHC results, and for offering a convincing explanation for the number of
generations in the Standard Model.Comment: 10 pages,7 figures. Matches Published EPJC versio
The impact of baryons on the direct detection of dark matter
The spatial and velocity distributions of dark matter particles in the Milky
Way Halo affect the signals expected to be observed in searches for dark
matter. Results from direct detection experiments are often analyzed assuming a
simple isothermal distribution of dark matter, the Standard Halo Model (SHM).
Yet there has been skepticism regarding the validity of this simple model due
to the complicated gravitational collapse and merger history of actual
galaxies. In this paper we compare the SHM to the results of cosmological
hydrodynamical simulations of galaxy formation to investigate whether or not
the SHM is a good representation of the true WIMP distribution in the analysis
of direct detection data. We examine two Milky Way-like galaxies from the
MaGICC cosmological simulations (a) with dark matter only and (b) with baryonic
physics included. The inclusion of baryons drives the shape of the DM halo to
become more spherical and makes the velocity distribution of dark matter
particles less anisotropic especially at large heliocentric velocities, thereby
making the SHM a better fit. We also note that we do not find a significant
disk-like rotating dark matter component in either of the two galaxy halos with
baryons that we examine, suggesting that dark disks are not a generic
prediction of cosmological hydrodynamical simulations. We conclude that in the
Solar neighborhood, the SHM is in fact a good approximation to the true dark
matter distribution in these cosmological simulations (with baryons) which are
reasonable representations of the Milky Way, and hence can also be used for the
purpose of dark matter direct detection calculations.Comment: Minor changes to match JCAP version. 21 pages, 9 figure
Multistability and metastability: understanding dynamic coordination in the brain
Multistable coordination dynamics exists at many levels, from multifunctional neural circuits in vertebrates and invertebrates to large-scale neural circuitry in humans. Moreover, multistability spans (at least) the domains of action and perception, and has been found to place constraints upon, even dictating the nature of, intentional change and the skill-learning process. This paper reviews some of the key evidence for multistability in the aforementioned areas, and illustrates how it has been measured, modelled and theoretically understood. It then suggests how multistability—when combined with essential aspects of coordination dynamics such as instability, transitions and (especially) metastability—provides a platform for understanding coupling and the creative dynamics of complex goal-directed systems, including the brain and the brain–behaviour relation
Preliminaries of a Space Situational Awareness Ontology
Space situational awareness (SSA) is vital for international safety and security, and for the future of space travel. The sharing of SSA data and information should improve the state of global SSA for planetary defense and spaceflight safety. I take steps toward a Space Situational Awareness (SSA) Ontology, and outline some central objectives, requirements and desiderata in the ontology development process for this domain. The purpose of this ontological system is to explore the potential for the ontology research topic to (i) represent SSA general knowledge, data, and entities/objects, (ii) clearly express the meaning of SSA data, and (iii) foster SSA data-sharing. The overall goal and motivation is to (iv) improve our capacity for planetary defense, e.g., from near- or deep-space objects and phenomena, and (v) facilitate safer and peaceful space access, navigation and travel, by improving global SSA. This research is thereby intended only for peaceful space-domain applications and uses, with particular interests in orbital debris. There is little application of ontology to the space domain as compared with other disciplines and little if any ontological development of SSA and related domains. In this respect, this paper offers novel concepts
The evolutionary history of human spindle genes includes back-and-forth gene flow with Neandertals
Proteins associated with the spindle apparatus, a cytoskeletal structure that ensures the proper segregation of chromosomes during cell division, experienced an unusual number of amino acid substitutions in modern humans after the split from the ancestors of Neandertals and Denisovans. Here, we analyze the history of these substitutions and show that some of the genes in which they occur may have been targets of positive selection. We also find that the two changes in the kinetochore scaffold 1 (KNL1) protein, previously believed to be specific to modern humans, were present in some Neandertals. We show that the KNL1 gene of these Neandertals shared a common ancestor with present-day Africans about 200,000 years ago due to gene flow from the ancestors (or relatives) of modern humans into Neandertals. Subsequently, some non-Africans inherited this modern human-like gene variant from Neandertals, but none inherited the ancestral gene variants. These results add to the growing evidence of early contacts between modern humans and archaic groups in Eurasia and illustrate the intricate relationships among these groups
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