15,392 research outputs found
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
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
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
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
A fractional porous medium equation
We develop a theory of existence, uniqueness and regularity for a porous
medium equation with fractional diffusion, in , with ,
and . An -contraction semigroup is
constructed and the continuous dependence on data and exponent is established.
Nonnegative solutions are proved to be continuous and strictly positive for all
,
Algunas fábulas de La Fontaine y algunas historias en forma de relato
Las fábulas de La Fontaine y analisis desde del géenro tras la traducción al español de las fábulas en verso.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Spatial Structures and Spatial Spillovers: A GME Approach
Spatial econometrics is a subdiscipline that have gained a huge popularity in the last twenty years, not only in theoretical econometrics but in empirical studies as well. Basically, spatial econometric methods measure spatial interaction and incorporate spatial structure into regression analysis. The specification of a matrix of spatial weights W plays a crucial role in the estimation of spatial models. The elements of this matrix measure the spatial relationships between two geographical locations i and j, and they are specified exogenously to the model. Several alternatives for W have been proposed in the literature, although binary matrices based on contiguity among locations or distance matrices are the most commons choices. One shortcoming of using this type of matrices for the spatial models is the impossibility of estimating “heterogeneous†spatial spillovers: the typical objective is the estimation of a parameter that measures the average spatial effect of the set of locations analysed. Roughly speaking, this is given by “ill-posed†econometric models where the number of (spatial) parameters to estimate is too large. In this paper, we explore the use of generalized maximum entropy econometrics (GME) to estimate spatial structures. This technique is very attractive in situations where one has to deal with estimation of “ill-posed†or “ill-conditioned†models. We compare by means of Monte Carlo simulations “classical†ML estimators with GME estimators in several situations with different availability of information.
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