21,677 research outputs found
Discovery Prospects of a Light Scalar in the NMSSM
We study a region in the NMSSM parameter space in which the mass of the
SM-like Higgs boson is uplifted by ~4-17 GeV, allowing for stop masses and
|A_t| <= 1 TeV alleviating the little fine tuning problem of the MSSM. An
uplift of the mass of the SM-like Higgs boson is possible in two distinct
regions in the NMSSM parameter space: Either for large lambda and small
tan(beta) or, through singlet-doublet mixing, for small lambda and large
tan(beta). For a mostly singlet-like Higgs state H_S with a mass below 125 GeV
we investigate possible direct or indirect search channels at the run II of the
LHC as function of the NMSSM-specific uplift of the mass of the SM-like Higgs
boson: Direct production of H_S in gluon fusion with H_S decaying into
diphotons, modified reduced couplings of the SM-like Higgs state, and the
possible production of H_S in ggF -> A -> Z + H_S. We find that the region
featuring singlet-doublet mixing can be tested if searches at the LHC at 13 TeV
for BSM Higgs bosons in the mass range 88 - 102 GeV decaying into diphotons
become sensitive to signal cross sections sigma(gg -> H_S -> diphotons) ~ 20
fb, or if measurements of the reduced coupling kappa_V(H_{SM}) of the SM Higgs
boson to electroweak gauge boson exclude (or confirm) the region
kappa_V(H_{SM}) <~ 0.93.Comment: 20 pages, 16 Figs., reference added, LPT Orsay 15-9
Simultaneous Search for Extra Light and Heavy Higgs Bosons via Cascade Decays
Models with extended Higgs sectors can contain several additional Higgs
states, heavier or lighter than the SM Higgs boson. The couplings of lighter
extra states to SM particles can be strongly reduced, leading to small cross
sections for their direct production. Heavier extra states can have larger
couplings to SM particles and, moreover, have large branching fractions into
lighter extra states, notably into a SM-like Higgs boson accompagnied by
another Higgs state which can be lighter or heavier than 125GeV.
Motivated by corresponding scenarios in the NMSSM we study the prospects for
the discovery or exclusion of cascade decays in the
, and final states
where either or can be SM-like. Significant regions of the NMSSM
parameter space can be tested by these searches. These are, however, not
confined to models of the NMSSM type.Comment: 34 pages, 64 figures, explanations, figures and reference added, to
appear in JHE
Human capital and other factors of the total productivity in Spanish Regions
The productivity evolution results a main factors indicators in order to explain the uneven growth of the different economic spaces and their different levels of welfare in a long run. Just, the crucial importance of productivity for economic growth can be derived from its relation to other indicators of economic performance. Among other factors, these include accumulation of physical and human capital, technological progress, resources allocation and efficiency, and competitiveness. For this reason, in this paper we elaborate in the first place an indicator of Total Factor Productivity for the Spain regions from of point of view of the theoretical justifications of the different methodological proposals. In the second place, and using the available statistics, we explain the unequal behaviour of the Total Factor Productivity (TFP) between these regions from a point of view that variables like public capital (infrastructure), human capital (qualification), technological capital (research and development), productive specialization, the different grades of resource's uses, the exploitation of scale economies ..., may justify the regional divergence in productivity terms.
Local quanta, unitary inequivalence, and vacuum entanglement
In this work we develop a formalism for describing localised quanta for a
real-valued Klein-Gordon field in a one-dimensional box . We quantise
the field using non-stationary local modes which, at some arbitrarily chosen
initial time, are completely localised within the left or the right side of the
box. In this concrete set-up we directly face the problems inherent to a notion
of local field excitations, usually thought of as elementary particles.
Specifically, by computing the Bogoliubov coefficients relating local and
standard (global) quantizations, we show that the local quantisation yields a
Fock space which is unitarily inequivalent to the standard one
. In spite of this, we find that the local creators and
annihilators remain well defined in the global Fock space , and
so do the local number operators associated to the left and right partitions of
the box. We end up with a useful mathematical toolbox to analyse and
characterise local features of quantum states in . Specifically,
an analysis of the global vacuum state in terms
of local number operators shows, as expected, the existence of entanglement
between the left and right regions of the box. The local vacuum
, on the contrary, has a very different character.
It is neither cyclic nor separating and displays no entanglement. Further
analysis shows that the global vacuum also exhibits a distribution of local
excitations reminiscent, in some respects, of a thermal bath. We discuss how
the mathematical tools developed herein may open new ways for the analysis of
fundamental problems in local quantum field theory.Comment: 28 pages, 8 figure
The planetary nebula nature and properties of IRAS18197-1118
IRAS18197-1118 is a stellar-like object that has been classified as a
planetary nebula from its radio continuum emission and high [SIII]9532 to
Paschen9 line intensity ratio, as derived from direct images. We present
intermediate- and high-resolution, optical spectroscopy, VLA 8.46 GHz radio
continuum data, and narrow-band optical images of IRAS18197-1118 aimed at
confirming its planetary nebula nature, and analyzing its properties. The
optical spectrum shows that IRAS18197-1118 is a medium-excitation planetary
nebula suffering a high extinction (c(H_beta) ~3.37). The optical images do not
resolve the object but the 8.46 GHz image reveals an elliptical shell of
~2.7x1.6 arcsec^2 in size, a compact central nebular region, and possible
bipolar jet-like features, indicating several ejection events. The existence of
a compact central nebula makes IRAS18197-1118 singular because this kind of
structure is observed in a few PNe only. An expansion velocity ~20 km/s and a
systemic velocity (LSR) ~+95 km/s are obtained for the object. An electron
density of ~3.4x10^4 cm-3 and an ionized mass of ~2.1x10^-2 M_sun are deduced
from the 8.46 GHz radio continuum data for an estimated statistical distance of
6 kpc. Helium abundance is high but nitrogen is not enriched, which is not
consistently reproduced by evolutionary models, suggesting different abundances
in the elliptical shell and central region. The properties of IRAS18197-1118
indicate a relatively young planetary nebula, favor a distance of >~6 kpc, and
strongly suggest that it is an inner-disc planetary nebula.Comment: Accepted by MNRAS. 8 pages, 5 figures, 4 table
Programmable active pixel sensor to investigate neural interactions within the retina
Detection of the visual scene by the eye and the resultant neural interactions of the retina-brain system give us our perception of sight. We have developed an Active Pixel Sensor (APS) to be used as a tool for both furthering understanding of these interactions via experimentation with the retina and to make developments towards a realisable retinal prosthesis. The sensor consists of 469 pixels in a hexagonal array. The pixels are interconnected by a programmable neural network to mimic lateral interactions between retinal cells. Outputs from the sensor are in the form of biphasic current pulse trains suitable to stimulate retinal cells via a biocompatible array. The APS will be described with initial characterisation and test results
Three-dimensional electrode array for brain slice culture
Multielektroder arrays (MEA) er rækker af elektroder mest i mikrometer størrelse, som er blevet brugt i stor omfang til at stimulere og måle elektrisk aktivitet fra neuronale netværker. Brug af disse for at analysere hjerne slices (hjerneskiver) kan give indsigt i interaktioner mellem neuroner, eftersom dyrkninger af hjerneskiver in vitro beholder funktionaliteten af netværkerne i den levende hjerne. Elektroder var designet og fabrikeret med det formal at optimere MEA præstationen ved stimulering af og måling fra hjerneskiver in vitro. Meget af arbejdet beskrevet her beskæftiger sig med studiet af silicium mikrofabrikations teknikker for at opnå 3D elektroder med en høj dimensionsforhold, som er de mest egnede til at interagere med hjerneskiver. Elektroderne blev karakteriseret bade elektrisk og mekanisk for at demonstrere deres bedre egenskaber ved elektriske malinger og væv indtrægningsevne. Ved et andet sæt eksperimenter, det fabrikeret MEA system blev forsøgt integreret med et dyrkningsplatform som skal gøre længerevarende målinger mulige. Baseret på eksisterende litteratur mange forskellige platformer blev udviklet og tested med hjerneskiver. Selvom dyrkningen af væv ikke var mulig i disse systemer, eksperimenterne viser at de mikrofluidiske dele af systemet var funktionelle og det var muligt at integrere MEA systemet med ved at modificere den og lave den del af gennemstrømningsmekanismen. Til sidst en mekanisme som var I stand til at flytte elektroderne ind og ud af hjerneskiveren blev udviklet, simuleret og testet. Systemet var i stand til at flytte MEA chippen. Selvom mindre modifikationer vil være ønskelige for at forbedre bevægelsespræcisionen, integrering af denne mekanisme med MEA chippen var mulig og funktionaliteten af systemet blev påvist
The Arecibo Galaxy Environment Survey VII : A Dense Filament With Extremely Long HI Streams
We present completed observations of the NGC 7448 galaxy group and background
volume as part of the blind neutral hydrogen Arecibo Galaxy Environment Survey
(AGES). Our observations cover a region spanning 5x4 degrees, over a redshift
range of approximately -2,000 < cz < 20,000 km/s. A total of 334 objects are
detected, mostly in three overdensities at cz 7,500, cz 9,600 and
cz 11,400 km/s. The galaxy density is extremely high (15 per square
degree) and many (24%) show signs of extended HI emission, including some
features as much as 800 kpc in projected length. We describe the overall
characteristics of this environment : kinematics, typical galaxy colours and
mass to light ratios, and substructure. To aid in the cataloguing of this data
set, we present a new FITS viewer (FRELLED : Fits Realtime Explorer of Low
Latency in Every Dimension). This incorporates interactive source cataloguing
tools which increase our source extraction speed by approximately a factor of
50.Comment: 15 pages, 13 figures, accepted for publication in MNRA
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