6,672 research outputs found
Semileptonic decays of the standard Higgs boson
The Higgs boson decay into a pair of real or virtual W bosons, with one of
them decaying leptonically, is predicted within the Standard Model to have the
largest branching fraction of all Higgs decays that involve an isolated
electron or muon, for M_h > 120 GeV. We compute analytically the
fully-differential width for this h -> l \nu jj decay at tree level, and then
explore some multi-dimensional cuts that preserve the region of large signal.
Future searches for semileptonic decays at the Tevatron and LHC, employing
fully-differential information as outlined here, may be essential for ruling
out or in the Higgs boson and for characterizing a Higgs signal.Comment: 17 pages, 5 .eps figure
Thermoelectric spin voltage in graphene
In recent years, new spin-dependent thermal effects have been discovered in
ferromagnets, stimulating a growing interest in spin caloritronics, a field
that exploits the interaction between spin and heat currents. Amongst the most
intriguing phenomena is the spin Seebeck effect, in which a thermal gradient
gives rise to spin currents that are detected through the inverse spin Hall
effect. Non-magnetic materials such as graphene are also relevant for spin
caloritronics, thanks to efficient spin transport, energy-dependent carrier
mobility and unique density of states. Here, we propose and demonstrate that a
carrier thermal gradient in a graphene lateral spin valve can lead to a large
increase of the spin voltage near to the graphene charge neutrality point. Such
an increase results from a thermoelectric spin voltage, which is analogous to
the voltage in a thermocouple and that can be enhanced by the presence of hot
carriers generated by an applied current. These results could prove crucial to
drive graphene spintronic devices and, in particular, to sustain pure spin
signals with thermal gradients and to tune the remote spin accumulation by
varying the spin-injection bias
Stable ultrahigh-density magneto-optical recordings using introduced linear defects
The stability of data bits in magnetic recording media at ultrahigh densities
is compromised by thermal `flips' -- magnetic spin reversals -- of nano-sized
spin domains, which erase the stored information. Media that are magnetized
perpendicular to the plane of the film, such as ultrathin cobalt films or
multilayered structures, are more stable against thermal self-erasure than
conventional memory devices. In this context, magneto-optical memories seem
particularly promising for ultrahigh-density recording on portable disks, and
bit densities of 100 Gbit inch have been demonstrated using recent
advances in the bit writing and reading techniques. But the roughness and
mobility of the magnetic domain walls prevents closer packing of the magnetic
bits, and therefore presents a challenge to reaching even higher bit densities.
Here we report that the strain imposed by a linear defect in a magnetic thin
film can smooth rough domain walls over regions hundreds of micrometers in
size, and halt their motion. A scaling analysis of this process, based on the
generic physics of disorder-controlled elastic lines, points to a simple way by
which magnetic media might be prepared that can store data at densities in
excess of 1 Tbit inch.Comment: 5 pages, 4 figures, see also an article in TRN News at
http://www.trnmag.com/Stories/041801/Defects_boost_disc_capacity_041801.htm
A Novel Frequency Analysis Method for Assessing Kir2.1 and Nav1.5 Currents
Voltage clamping is an important tool for measuring individual currents from an electrically active cell. However, it is difficult to isolate individual currents without pharmacological or voltage inhibition. Herein, we present a technique that involves inserting a noise function into a standard voltage step protocol, which allows one to characterize the unique frequency response of an ion channel at different step potentials. Specifically, we compute the fast Fourier transform for a family of current traces at different step potentials for the inward rectifying potassium channel, Kir2.1, and the channel encoding the cardiac fast sodium current, Nav1.5. Each individual frequency magnitude, as a function of voltage step, is correlated to the peak current produced by each channel. The correlation coefficient vs. frequency relationship reveals that these two channels are associated with some unique frequencies with high absolute correlation. The individual IV relationship can then be recreated using only the unique frequencies with magnitudes of high absolute correlation. Thus, this study demonstrates that ion channels may exhibit unique frequency responses
Pure-glue hidden valleys through the Higgs portal
We consider the possibility that the Higgs boson can act as a link to a
hidden sector in the context of pure-glue hidden valley models. In these models
the standard model is weakly coupled, through loops of heavy messengers fields,
to a hidden sector whose low energy dynamics is described by a pure-Yang-Mills
theory. Such a hidden sector contains several metastable hidden glueballs. In
this work we shall extend earlier results on hidden valleys to include
couplings of the messengers to the standard model Higgs sector. The effective
interactions at one-loop couple the hidden gluons to the standard model
particles through the Higgs sector. These couplings in turn induce hidden
glueball decays to fermion pairs, or cascade decays with multiple Higgs
emission. The presence of effective operators of different mass dimensions,
often competing with each other, together with a great diversity of states,
leads to a great variability in the lifetimes and decay modes of the hidden
glueballs. We find that most of the operators considered in this paper are not
heavily constrained by precision electroweak physics, therefore leaving plenty
of room in the parameter space to be explored by the future experiments at the
LHC.Comment: 44 pages, 16 figures. Major revision for JHEP, corrected an error in
Eq. 5.1, comments adde
How the other half lives: CRISPR-Cas's influence on bacteriophages
CRISPR-Cas is a genetic adaptive immune system unique to prokaryotic cells
used to combat phage and plasmid threats. The host cell adapts by incorporating
DNA sequences from invading phages or plasmids into its CRISPR locus as
spacers. These spacers are expressed as mobile surveillance RNAs that direct
CRISPR-associated (Cas) proteins to protect against subsequent attack by the
same phages or plasmids. The threat from mobile genetic elements inevitably
shapes the CRISPR loci of archaea and bacteria, and simultaneously the
CRISPR-Cas immune system drives evolution of these invaders. Here we highlight
our recent work, as well as that of others, that seeks to understand phage
mechanisms of CRISPR-Cas evasion and conditions for population coexistence of
phages with CRISPR-protected prokaryotes.Comment: 24 pages, 8 figure
Real-Time Big Data Analytics in Smart Cities from LoRa-Based IoT Networks
The currently burst of the Internet of Things (IoT) tech-nologies
implies the emergence of new lines of investigation regarding not only to hardware
and protocols but also to new methods of pro-duced data analysis satisfying the
IoT environment constraints: a real-time and a big data approach. The Real-time
restriction is about the continuous generation of data provided by the endpoints
connected to an IoT network; due to the connection and scaling capabilities of an IoT
network, the amount of data to process is so high that Big data tech-niques
become essential. In this article, we present a system consisting of two main
modules. In one hand, the infrastructure, a complete LoRa based network designed,
tested and deployment in the Pablo de Olavide University and, on the other side, the
analytics, a big data streaming sys-tem that processes the inputs produced by the
network to obtain useful, valid and hidden information.Ministerio de Economía y Competitividad TIN2017-88209-C2-1-
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