12,286 research outputs found
Scalegenesis and fermionic dark matters in the flatland scenario
We propose an extension of the standard model with Majorana-type fermionic
dark matters based on the flatland scenario where all scalar coupling
constants, including scalar mass terms, vanish at the Planck scale, i.e. the
scalar potential is flat above the Planck scale. This scenario could be
compatible with the asymptotic safety paradigm for quantum gravity. We search
the parameter space so that the model reproduces the observed values such as
the Higgs mass, the electroweak vacuum and the relic abundance of dark matter.
We also investigate the spin-independent elastic cross section for the Majorana
fermions and a nucleon. It is shown that the Majorana fermions as dark matter
candidates could be tested by dark matter direct detection experiments such as
XENON, LUX and PandaX-II. We demonstrate that within the minimal setup
compatible with the flatland scenario at the Planck scale or asymptotically
safe quantum gravity, the extended model could have a strong predictability.Comment: 23 pages, 9 figures, Version published in EPJ
Possible link of a structurally driven spin flip transition and the insulator-metal transition in the perovskite LaBaCoO
The complex nature of the magnetic ground state in LaACoO
(A = Ca, Sr, Ba) has been investigated via neutron scattering. It was
previously observed that ferromagnetic (FM) as well as antiferromagnetic (AFM)
correlations can coexist prior to the insulator-metal transition (IMT). We
focused on a unique region in the Ba phase diagram, from x = 0.17 - 0.22, in
which a commensurate AFM phase appears first with a propagation vector, k = (0,
-0.5, 0.5), and the Co moment in the (001) plane of the rhombohedral
lattice. With increasing x, the AFM component weakens while an FM order appears
with the FM Co moment directed along the (001) (=(111)) axis. By x
= 0.22, a spin flip to new FM component appears as the crystal fully transforms
to an orthorhombic (Pnma) structure, with the Co moments pointing along a new
direction, (001) (=(110)). It is the emergence of the magnetic Pnma
phase that leads to IMT.Comment: 5 page
Localization of Electronic States in Chain Model Based on Real DNA Sequence
We investigate the localization property of an electron in the disordered
two-chain system (ladder model) with long-range correlation as a simple model
for electronic property in DNA sequence. The chains are constructed by
repetition of the sugar-phosphate sites, and the inter-chain hopping at the
sugar sites come from nucleotide pairs, i.e., or pairs. It has been
found that some DNA sequences have long-range correlation. In this paper we use
some actual DNA sequences such as bacteriophages of escherichia coli, human
omosome 22 and histone protein as the correlated sequence for the interchain
hopping at the sugar sites. We will present some numerical results for the
Lyapunov exponent (inverse localization length) of the wave function in the
cases in comparison to the results for artificial sequence generated by an
asymmetric modified Bernoulli map. It is shown that the correlation and
asymmetry of the sequence affect on the localization in both the artificial and
real DNA sequences.Comment: 12 pages, 4 figure
- β¦