7,241 research outputs found
Hunting for heavy composite Majorana neutrinos at the LHC
We investigate the search for heavy Majorana neutrinos stemming from a
composite model scenario at the upcoming LHC Run II at a center of mass energy
of 13 TeV. While previous studies of the composite Majorana neutrino were
focussed on gauge interactions via magnetic type transition coupling between
ordinary and heavy fermions (with mass ) here we complement the composite
model with contact interactions at the energy scale and we find that
the production cross sections are dominated by such contact interactions by
roughly two/three orders of magnitude. This mechanism provides therefore very
interesting rates at the prospected luminosities. We study the same sign
di-lepton and di-jet signature () and perform a fast
detector simulation based on Delphes. We compute 3 and 5
contour plots of the statistical significance in the parameter space
(). We find that the potentially excluded regions at TeV are quite larger than those excluded so far at Run I considering
searches with other signatures.Comment: 14 pages, 9 figures, Minor comments and few references added. Version
accepted by the European Physical Journal C (EPJC
Low energy phases of bilayer Bi predicted by structure search in two dimensions
We employ an ab-initio structure search algorithm to explore the
configurational space of Bi in quasi two dimensions. A confinement potential
restricts the movement of atoms within a pre-defined thickness during structure
search calculations within the minima hopping method to find the stable and
metastable forms of bilayer Bi. In addition to recovering the two known
low-energy structures (puckered monoclinic and buckled hexagonal), our
calculations predict three new structures of bilayer Bi. We call these
structures the , , and phases of bilayer Bi, which are,
respectively, 63, 72, and 83 meV/atom higher in energy than that of the
monoclinic ground state, and thus potentially synthesizable using appropriate
substrates. We also compare the structural, electronic, and vibrational
properties of the different phases. The puckered monoclinic, buckled hexagonal,
and phases exhibit a semiconducting energy gap, whereas and
phases are metallic. We notice an unusual Mexican-hat type band
dispersion leading to a van Hove singularity in the buckled hexagonal bilayer
Bi. Notably, we find symmetry-protected topological Dirac points in the
electronic spectrum of the phase. The new structures suggest that
bilayer Bi provides a novel playground to study distortion-mediated
metal-insulator phase transitions
Variations in the lectin-binding on the zona pellucida during oocyte growth in some wild ungulates
The aim of the present study was to examine the glycoconjugate modifications occurring in the zona pellucida during oocyte growth in fallow, red and roe deer using a battery of lectins combined with sialidase digestion and chemical treatments. This histochemical approach allowed us to sequence the oligosaccharidic side chains of the zona pellucida glycoproteins in these wild ungulates. The most effective lectins in the zona pellucida of these species were SBA, PNA, RCA-I GSA-IB4, and WGA, indicating the presence of beta-D-N-Acetylgalactosamine, beta-D-Galactose, alpha-D-Galactose and N-Acetylglucosamine residues. Additionally, sialic acid moieties were demonstrated. We also observed differences in the glycosidic residue content and in their spatial distribution, depending on the species and stage of follicle development
Compact, low power and low threshold electrically pumped micro disc lasers for 20Gb/s non return to zero all optical wavelength conversion
\u3cp\u3eUsing a 7.5μm wide InP Micro-Disc-Laser, with a very low ∼100μA threshold current, heterogeneously integrated on top of Silicon on Insulator substrate, all optical NRZ wavelength conversion at speeds up to 20Gb/s is demonstrated.\u3c/p\u3
Density Enhancement Streams in The Solar Wind
This letter describes a new phenomenon on the Parker Solar Probe of recurring
plasma density enhancements that have n/n ~10% and that occur at a
repetition rate of ~5 Hz. They were observed sporadically for about five hours
between 14 and 15 solar radii on Parker Solar Probe orbit 12 and they were also
seen in the same radial range on both the inbound and outbound orbits 11. Their
apparently steady-state existence suggests that their pressure gradient was
balanced by the electric field. The EX electric field component produced from
this requirement is in good agreement with that measured. This provides strong
evidence for the measurement accuracy of the density fluctuations and the X-
and Y-components of the electric field (the Z-component was not measured). The
electrostatic density waves were accompanied by an electromagnetic low
frequency wave which occurred with the electrostatic harmonics. The amplitudes
of these electrostatic and electromagnetic waves at 1 Hz were greater
than the amplitude of the Alfvenic turbulence in their vicinity so they can be
important for the heating, scattering, and acceleration of the plasma. The
existence of this pair of waves is consistent with the observed plasma
distributions and is explained by a magneto-acoustic wave theory that produces
a low frequency electromagnetic wave and electrostatic harmonics.Comment: 9 pages including 5 figure
The effects of industrial wastes from Charmin Paper Products Company on fish of the Cheboygan river drainage system
This study investigated effects of industrial wastes of a paper mill on fish. Chemical analyses were made of the effluent and of the river water before it entered the mill and at the effluent entry point. Static bioassay techniques were used to determine tolerances to the effluent of ten fish species which were abundant in the paper mill area. Fish were collected from the effluent entry point into the river. An abundant fish fauna was found. Charmin Paper Products Company, Cheboygan, Michigan, treats its waste products thoroughly and is an example of what an industry can do to reduce water pollution. The common shiner, Notropis cornutus, was found to be intolerant to even low concentrations of the effluent. Thus, its presence in an area would indicate a very low level of pollution of this type.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33355/1/0000753.pd
Stress-energy tensor for a quantised bulk scalar field in the Randall-Sundrum brane model
We calculate the vacuum expectation value of the stress-energy tensor for a
quantised bulk scalar field in the Randall-Sundrum model, and discuss the
consequences of its local behaviour for the self-consistency of the model. We
find that, in general, the stress-energy tensor diverges in the vicinity of the
branes. Our main conclusion is that the stress-energy tensor is sufficiently
complicated that it has implications for the effective potential, or radion
stabilisation, methods that have so far been used.Comment: 16 pages, 3 figures. Minor changes made and references added. To
appear in Phys. Rev.
Vacuum destabilization from Kaluza-Klein modes in an inflating brane
We discuss the effects from the Kaluza-Klein modes in the brane world
scenario when an interaction between bulk and brane fields is included. We
focus on the bulk inflaton model, where a bulk field drives inflation in
an almost bulk bounded by an inflating brane. We couple to a
brane scalar field representing matter on the brane. The bulk field
is assumed to have a light mode, whose mass depends on the expectation
value of . To estimate the effects from the KK modes, we compute the
1-loop effective potential V_\eff(\phi). With no tuning of the parameters of
the model, the vacuum becomes (meta)stable -- V_\eff(\phi) develops a true
vacuum at a nonzero . In the true vacuum, the light mode of
becomes heavy, degenerates with the KK modes and decays. We comment on some
implications for the bulk inflaton model. Also, we clarify some aspects of the
renormalization procedure in the thin wall approximation, and show that the
fluctuations in the bulk and on the brane are closely related.Comment: 15 pages, 2 eps figures. Notation improved, references adde
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