2,713 research outputs found
A possible supersymmetric solution to the discrepancy between B -> \phi K_S and B -> \eta' K_S CP asymmetries
We present a possible supersymmetric solution to the discrepancy between the
observed mixing CP asymmetries in B -> \phi K_S and B -> \eta' K_S. We show
that due to the different parity in the final states of these processes, their
supersymmetric contributions from the R-sector have an opposite sign, which
naturally explain the large deviation between S_{\phi K_S} and S_{\eta' K_S}.
We also consider the proposed mechanisms to solve the puzzle of the observed
large branching ratio of B -> \eta' K and study their impact on S_{eta' K_S}.Comment: 4 pages, 2 figure
Collective Engagement in Creative Tasks: The Role of Evaluation in the Creative Process in Groups
Research on group creativity has concentrated on explaining how the group context influences idea generation and has conceptualized the evaluation of creative ideas as a process of convergent decision making that takes place after ideas are generated to improve the quality of the group’s creative output. We challenge this view by exploring the situated nature of evaluations that occur throughout the creative process. We present an inductive qualitative process analysis of four U.S. healthcare policy groups tasked with producing creative output in the form of policy recommendations to a federal agency. Results show four modes of group interaction, each with a distinct form of evaluation: brainstorming without evaluation, sequential interactions in which one idea was generated and evaluated, parallel interactions in which several ideas were generated and evaluated, and iterative interactions in which the group evaluated several ideas in reference to the group’s goals. Two of the groups in our study followed an evaluation-centered sequence that began with evaluating a small set of ideas. Surprisingly, doing so did not impede the groups’ creativity. To explain this, we develop an alternative conceptualization of evaluation as a generative process that shapes and guides collective creativity
Anomalous Spin Dynamics of Hubbard Model on Honeycomb Lattices
In this paper, the honeycomb Hubbard model in optical lattices is
investigated using O(3) non-linear sigma model. A possible quantum non-magnetic
insulator in a narrow parameter region is found near the metal-insulator
transition. We study the corresponding dynamics of magnetic properties, and
find that the narrow region could be widened by hole doping.Comment: 9 pages, 12 figure
A Review of Artificial Intelligence Based Research Results in Agriculture and Livestock Industry
In recent years, China's agricultural and animal husbandry industry has gradually developed
towards scale and intelligence, a process that cannot be achieved without the progress and
implementation of scientific research. This article takes the Grassland Animal Husbandry
Traceability Big Data Inner Mongolia Autonomous Region Engineering Laboratory of Inner
Mongolia University of Science and Technology as an example, and introduces four research
results related to agriculture and animal husbandry in this laboratory
Coexistence of Itinerant Electrons and Local Moments in Iron-Based Superconductors
In view of the recent experimental facts in the iron-pnictides, we make a
proposal that the itinerant electrons and local moments are simultaneously
present in such multiband materials. We study a minimal model composed of
coupled itinerant electrons and local moments to illustrate how a consistent
explanation of the experimental measurements can be obtained in the leading
order approximation. In this mean-field approach, the spin-density-wave (SDW)
order and superconducting pairing of the itinerant electrons are not directly
driven by the Fermi surface nesting, but are mainly induced by their coupling
to the local moments. The presence of the local moments as independent degrees
of freedom naturally provides strong pairing strength for superconductivity and
also explains the normal-state linear-temperature magnetic susceptibility above
the SDW transition temperature. We show that this simple model is supported by
various anomalous magnetic properties and isotope effect which are in
quantitative agreement with experiments.Comment: 7 pages, 4 figures; an expanded versio
semileptonic form factors from lattice QCD with M\"obius domain-wall quarks
We calculate the form factors for the decay in 2+1
flavor lattice QCD. For all quark flavors, we employ the M\"obius domain-wall
action, which preserves chiral symmetry to a good precision. Our gauge
ensembles are generated at three lattice cutoffs , 3.6 and 4.5
GeV with pion masses as low as MeV. The physical lattice size
satisfies the condition to control finite volume effects
(FVEs), while we simulate a smaller size at the smallest to directly
examine FVEs. The bottom quark masses are chosen in a range from the physical
charm quark mass to to control discretization effects. We
extrapolate the form factors to the continuum limit and physical quark masses
based on heavy meson chiral perturbation theory at next-to-leading order. Then
the recoil parameter dependence is parametrized using a model independent form
leading to our estimate of the decay rate ratio between the tau ()
and light lepton () channels in the Standard
Model. A simultaneous fit with recent data from the Belle experiment yields
, which is consistent with previous
exclusive determinations, and shows good consistency in the kinematical
distribution of the differential decay rate between the lattice and
experimental data.Comment: 37 pages, 13 figure
Study of pure annihilation type decays
In this work, we calculate the rare decays and in perturbative QCD approach with Sudakov resummation.
We give the branching ratio of for , which will
be tested soon in factories.
The decay has a very small branching ratio at
, due to the suppression from CKM matrix elements . It may be sensitive to new physics contributions.Comment: 14 pages, 1 figur
Mott physics, sign structure, ground state wavefunction, and high-Tc superconductivity
In this article I give a pedagogical illustration of why the essential
problem of high-Tc superconductivity in the cuprates is about how an
antiferromagnetically ordered state can be turned into a short-range state by
doping. I will start with half-filling where the antiferromagnetic ground state
is accurately described by the Liang-Doucot-Anderson (LDA) wavefunction. Here
the effect of the Fermi statistics becomes completely irrelevant due to the no
double occupancy constraint. Upon doping, the statistical signs reemerge,
albeit much reduced as compared to the original Fermi statistical signs. By
precisely incorporating this altered statistical sign structure at finite
doping, the LDA ground state can be recast into a short-range antiferromagnetic
state. Superconducting phase coherence arises after the spin correlations
become short-ranged, and the superconducting phase transition is controlled by
spin excitations. I will stress that the pseudogap phenomenon naturally emerges
as a crossover between the antiferromagnetic and superconducting phases. As a
characteristic of non Fermi liquid, the mutual statistical interaction between
the spin and charge degrees of freedom will reach a maximum in a
high-temperature "strange metal phase" of the doped Mott insulator.Comment: 12 pages, 12 figure
New Family of Robust 2D Topological Insulators in van der Waals Heterostructures
We predict a new family of robust two-dimensional (2D) topological insulators
in van der Waals heterostructures comprising graphene and chalcogenides BiTeX
(X=Cl, Br and I). The layered structures of both constituent materials produce
a naturally smooth interface that is conducive to proximity induced new
topological states. First principles calculations reveal intrinsic
topologically nontrivial bulk energy gaps as large as 70-80 meV, which can be
further enhanced up to 120 meV by compression. The strong spin-orbit coupling
in BiTeX has a significant influence on the graphene Dirac states, resulting in
the topologically nontrivial band structure, which is confirmed by calculated
nontrivial Z2 index and an explicit demonstration of metallic edge states. Such
heterostructures offer an unique Dirac transport system that combines the 2D
Dirac states from graphene and 1D Dirac edge states from the topological
insulator, and it offers new ideas for innovative device designs
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