1,499 research outputs found
Anomalous magnetic and weak magnetic dipole moments of the lepton in the simplest little Higgs model
We obtain analytical expressions, both in terms of parametric integrals and
Passarino-Veltman scalar functions, for the one-loop contributions to the
anomalous weak magnetic dipole moment (AWMDM) of a charged lepton in the
framework of the simplest little Higgs model (SLHM). Our results are general
and can be useful to compute the weak properties of a charged lepton in other
extensions of the standard model (SM). As a by-product we obtain generic
contributions to the anomalous magnetic dipole moment (AMDM), which agree with
previous results. We then study numerically the potential contributions from
this model to the lepton AMDM and AWMDM for values of the parameter
space consistent with current experimental data. It is found that they depend
mainly on the energy scale at which the global symmetry is broken and the
parameter, whereas there is little sensitivity to a mild change in
the values of other parameters of the model. While the AMDM is of the
order of , the real (imaginary) part of its AWMDM is of the order of
(). These values seem to be out of the reach of the
expected experimental sensitivity of future experiments.Comment: 23 pages, 11 figures, new analysis and References adde
Self-organized patterns of coexistence out of a predator-prey cellular automaton
We present a stochastic approach to modeling the dynamics of coexistence of
prey and predator populations. It is assumed that the space of coexistence is
explicitly subdivided in a grid of cells. Each cell can be occupied by only one
individual of each species or can be empty. The system evolves in time
according to a probabilistic cellular automaton composed by a set of local
rules which describe interactions between species individuals and mimic the
process of birth, death and predation. By performing computational simulations,
we found that, depending on the values of the parameters of the model, the
following states can be reached: a prey absorbing state and active states of
two types. In one of them both species coexist in a stationary regime with
population densities constant in time. The other kind of active state is
characterized by local coupled time oscillations of prey and predator
populations. We focus on the self-organized structures arising from
spatio-temporal dynamics of the coexistence. We identify distinct spatial
patterns of prey and predators and verify that they are intimally connected to
the time coexistence behavior of the species. The occurrence of a prey
percolating cluster on the spatial patterns of the active states is also
examined.Comment: 19 pages, 11 figure
Has a Higgs-flavon with a GeV mass been detected at the LHC13?
Higgs-flavon fields appear as a part of the Froggatt-Nielsen (FN) mechanism,
which attempts to explain the hierarchy of Yukawa couplings. We explore the
possibility that the 750 GeV diphoton resonance recently reported at the LHC13,
could be identified with a low-scale Higgs-flavon field and find the
region of the parameter space consistent with CMS and ATLAS data. It is found
that the extra vector-like fermions of the ultraviolet completion of the FN
mechanism are necessary in order to reproduce the observed signal. We consider
a standard model (SM) extension that contains two Higgs doublets (a standard
one and an inert one) and one complex FN singlet. The inert doublet includes a
stable neutral boson, which provides a viable dark matter candidate, while the
mixing of the standard doublet and the FN singlet induces flavor violation in
the Higgs sector at the tree-level. Constraints on the parameters of the model
are derived from the LHC Higgs data, which include the search for the lepton
flavor violating decay of the SM Higgs boson . It is also
found that in some region of the parameter space the model may give rise to a
large branching ratio for the decay, of the order of 0.1, which
could be searched for at the LHC.Comment: 18 pages, 7 Figures, includes updated files to match published
versio
SIRS dynamics on random networks: simulations and analytical models
The standard pair approximation equations (PA) for the
Susceptible-Infective-Recovered-Susceptible (SIRS) model of infection spread on
a network of homogeneous degree predict a thin phase of sustained
oscillations for parameter values that correspond to diseases that confer long
lasting immunity. Here we present a study of the dependence of this oscillatory
phase on the parameter and of its relevance to understand the behaviour of
simulations on networks. For , we compare the phase diagram of the PA
model with the results of simulations on regular random graphs (RRG) of the
same degree. We show that for parameter values in the oscillatory phase, and
even for large system sizes, the simulations either die out or exhibit damped
oscillations, depending on the initial conditions. This failure of the standard
PA model to capture the qualitative behaviour of the simulations on large RRGs
is currently being investigated.Comment: 6 pages, 3 figures, WIPP to be published in Conference proceedings
Complex'2009 February 23-25, Shanghai, Chin
The effects of language dominance switch in bilinguals: Galician new speakers' speech production and perception
It has long been debated whether speech production and perception remain flexible in adulthood. The current study investigates the effects of language dominance switch in Galician new speakers (neofalantes) who are raised with Spanish as a primary language and learn Galician at an early age in a bilingual environment, but in adolescence, decide to switch to using Galician almost exclusively, for ideological reasons. Results showed that neofalantes pattern with Spanish-dominants in their perception and production of mid-vowel and fricative contrasts, but with Galician-dominants in their realisation of unstressed word-final vowels, a highly salient feature of Galician. These results are taken to suggest that despite early exposure to Galician, high motivation and almost exclusive Galician language use post-switch, there are limitations to what neofalantes can learn in both production and perception, but that the hybrid categories they appear to develop may function as opportunities to mark identity within a particular community
Linear Invariant Systems Theory for Signal Enhancement
This paper discusses a linear time invariant (LTI) systems approach to signal enhancement via projective subspace techniques. It provides closed form expressions for the frequency response of data adaptive finite impulse response eigenfilters. An illustrative example using speech enhancement is also presented.Este artigo apresenta a aplicação da teoria de sistemas lineares invariantes no tempo (LTI) na anĂĄlise de tĂ©cnicas de sub-espaço. A resposta em frequĂȘncia dos filtros resultantes da decomposição em valores singulares Ă© obtida aplicando as propriedades dos sistemas LTI
cLFV processes and suppression of non-unitary mixing effects in low scale seesaw models
We examine the parameter space region of the inverse seesaw model that is
consistent with neutrino oscillation data. We focus on the correlation between
the current limits from the search of the lepton flavour
violating decay and the non-standard effects associated with the presence of
new heavy neutrino states. Unlike what we would expect from an inverse seesaw
model, we have found a parametrization for the mass matrices in which the rates
of charged lepton flavour-violating processes are negligible. Additionally, we
provide a model where the inverse seesaw is obtained naturally, and the mass
matrices get this structure with negligible violation of the lepton flavour.Comment: 20 pages, 3 figures and 3 table
IMUNOTERAPIA COM VENENO DE HIMENĂPTEROS: A EXPERIĂNCIA DE UMA CONSULTA
Resumo: Na Europa a prevalĂȘncia de alergia ao veneno de himenĂłpteros estima-se em 20%. As reacçÔes sistĂ©micas graves sĂŁo indicação para imunoterapia especĂfica com veneno de himenĂłpteros apĂłs confirmação de atopia. Esta Ă© eficaz em 91-100% dos casos de alergia ao veneno de vespa e 77-80% dos casos de alergia ao veneno de abelha. Apresentamos quatro casos clĂnicos de doentes com reacçÔes sistĂ©micas ao veneno de himenĂłpteros que efectuaram imunoterapia. TrĂȘs crianças apresentavam alergia ao veneno de abelha e uma ao veneno de vespa. Tinham IgE especĂfica para o veneno de himenĂłpteros, classes IV a VI. A duração da imunoterapia variou entre quatro e sete anos, com diminuição da classe de IgE especĂfica em todos os doentes no final do tratamento. TrĂȘs crianças tiveram contacto com o alergĂ©nio, durante ou apĂłs terminarem a imunoterapia, e nenhuma delas desencadeou uma reacção sistĂ©mica. A duração da imunoterapia continua a ser controversa. A ausĂȘncia de reacção apĂłs contacto com o alergĂ©nio Ă© sugestiva de sucesso do tratamento
Ï parameter and H 0 â â i â j in models with TeV sterile neutrinos
The presence of massive sterile neutrinos
N
mixed with the active ones induces flavor violating processes in the charged lepton sector at the loop level. In particular, the amplitude of
H
0
â
ÂŻ
â
i
â
j
is expected to be proportional to the product of heavy-light Yukawa couplings
y
i
y
j
=
2
s
Μ
i
s
Μ
j
m
2
N
/
v
2
, where
s
Μ
i
,
j
express the heavy-light neutrino mixings. Here, we revisit these Higgs decays in the most generic extension of the neutrino sector, focusing on large values of
y
i
. We show that decoupling effects and a cancellation between the two dominant contributions to these processes makes the amplitude about 100 times smaller than anticipated. We find that perturbative values of
y
i
giving an acceptable contribution to the
Ï
parameter imply
B
(
H
0
â
ÂŻ
â
i
â
j
)
<
10
â
8
for any lepton flavors, a rate that is not accessible at current colliders.Spanish Ministry of Science, Innovation and Universities
FPA2016-78220-C3
PID2019-107844GB-C21/AEI/10.13039/501100011033Junta de Andalucia
FQM 101
SOMM17/6104/UGR
P18-FR-1962
P18-FR-5057Consejo Nacional de Ciencia y Tecnologia (CONACyT
- âŠ