1,720 research outputs found
Measurement of the CR primary spectrum with ARGO-YBJ
The study of cosmic rays below 1015 eV is one of the main goals of the ARGO-YBJ experiment. In this paper we will report on the measurement of the primary light component spectrum
Early-childhood BMI trajectories: evidence from a prospective, nationally representative British cohort study
Background and Objectives: By age 5, 20% of British children are classed as overweight or obese, suggesting that early childhood is crucial for lifelong body mass index (BMI) trajectories. In this paper, we identify latent trajectories of early-childhood BMI from ages 3 to 11 years. Given the current context of growing socio-economic inequalities in childhood and adult overweight and obesity, we examine the socio-economic characteristics and mechanisms during pregnancy and infancy which underscore these trajectories.Subject and Methods: We use a nationally representative, prospective cohort study of 9699 children born in 2000–2002, living in the United Kingdom shortly after birth, with complete information on height and weight (measured by an interviewer) at ages 3, 5, 7 and 11. Trajectories of BMI are calculated using latent growth mixture models. Multinomial models characterize these trajectories by their socio-economic profiles and mechanisms during pregnancy and infancy.Results: Four trajectories were identified: two separate trajectories where BMI remains within a normal range (85% of the sample), an overweight trajectory (14.4%), and an obese trajectory (3.1%). No ‘declining BMI’ or late-onset groups were found. The obese group is already distinct from the other trajectories by age 3. The overweight group diverges from the normal groups around age 5. Strong socio-economic inequalities emerged; for the obese group, part of this disadvantage is mediated through early mechanisms such as pregnancy smoke and not initiating breastfeeding.Conclusions: This study provides strong evidence for the idea that childhood BMI trajectories develop early, especially for children who will follow an obese trajectory. Strong socio-economic patterns in these trajectories suggest that the observed trend in growing inequalities may be rooted in early life. Mediating mechanisms for the obese appear to be in the pregnancy and infant period, further research should explore mechanisms occurring around age 5 when the overweight trajectory diverges
Observation of Horizontal Air Showers with ARGO-YBJ
Abstract A preliminary analysis of Extensive Air Showers reconstructed by ARGO-YBJ with zenith angle greater than 80° is reported. The measurement of the size spectrum and of the azimuthal distribution is discussed. A description of the topology of these events is also provided
Weak Mixing Angle and Higgs Mass in Gauge-Higgs Unification Models with Brane Kinetic Terms
We show that the idea of Gauge-Higgs unification(GHU) can be rescued from the
constraint of weak mixing angle by introducing localized brane kinetic terms in
higher dimensional GHU models with bulk and simple gauge groups. We find that
those terms lead to a ratio between Higgs and W boson masses, which is a little
bit deviated from the one derived in the standard model. From numerical
analysis, we find that the current lower bound on the Higgs mass tends to
prefer to exceptional groups E(6), E(7), E(8) rather than other groups like
SU(3l), SO(2n+1), G(2), and F(4) in 6-dimensional(D) GHU models irrespective of
the compactification scales. For the compactification scale below 1 TeV, the
Higgs masses in 6D GHU models with SU(3l), SO(2n+1), G(2), and F(4) groups are
predicted to be less than the current lower bound unless a model parameter
responsible for re-scaling SU(2) gauge coupling is taken to be unnaturally
large enough. To see how the situation is changed in more higher dimensional
GHU model, we take 7D S^{3}/ Z_{2} and 8D T^{4}/ Z_{2} models. It turns out
from our numerical analysis that these higher dimensional GHU models with gauge
groups except for E(6) can lead to the Higgs boson whose masses are predicted
to be above the current lower bound only for the compatification scale above 1
TeV without taking unnaturally large value of the model parameter, whereas the
Higgs masses in the GHU models with E(6) are compatible with the current lower
bound even for the compatification scale below 1 TeV.Comment: 22 pages, 4 figure
On electroweak baryogenesis in the littlest Higgs model with T parity
We study electroweak baryogenesis within the framework of the littlest Higgs
model with T parity. This model has shown characteristics of a strong
first-order electroweak phase transition, which is conducive to baryogenesis in
the early Universe. In the T parity symmetric theory, there are two gauge
sectors, viz., the T-even and the T-odd ones. We observe that the effect of the
T-parity symmetric interactions between the T-odd and the T-even gauge bosons
on gauge-higgs energy functional is quite small, so that these two sectors can
be taken to be independent. The T-even gauge bosons behave like the Standard
Model gauge bosons, whereas the T-odd ones are instrumental in stabilizing the
Higgs mass. For the T-odd gauge bosons in the symmetric and asymmetric phases
and for the T-even gauge bosons in the asymmetric phase, we obtain, using the
formalism of Arnold and McLerran, very small values of the ratio, (Baryon
number violation rate/Universe expansion rate). We observe that this result, in
conjunction with the scenario of inverse phase transition in the present work
and the value of the ratio obtained from the lattice result of sphaleron
transition rate in the symmetric phase, can provide us with a plausible
baryogenesis scenario.Comment: 13 pages, 2 figures, published version, references modifie
Bounding wide composite vector resonances at the LHC
In composite Higgs models (CHMs), electroweak precision data generically push
colourless composite vector resonances to a regime where they dominantly decay
into pairs of light top partners. This greatly attenuates their traces in
canonical collider searches, tailored for narrow resonances promptly decaying
into Standard Model final states. By reinterpreting the CMS same-sign dilepton
(SS2) analysis at the Large Hadron Collider (LHC), originally designed to
search for top partners with electric charge , we demonstrate its
significant coverage over this kinematical regime. We also show the reach of
the 13 TeV run of the LHC, with various integrated luminosity options, for a
possible upgrade of the SS2 search. The top sector of CHMs is found to be
more fine-tuned in the presence of colourless composite resonances in the few
TeV range.Comment: 9 pages, 5 figures. Minor corrections for publication in JHE
The Discrete Composite Higgs Model
We describe a concrete, predictive incarnation of the general paradigm of a
composite Higgs boson, which provides a valid alternative to the standard
holographic models in five space-time dimensions. Differently from the latter,
our model is four-dimensional and simple enough to be implemented in an event
generator for collider studies. The model is inspired by dimensional
deconstruction and hence it retains useful features of the five-dimensional
scenario, in particular, the Higgs potential is finite and calculable.
Therefore our setup, in spite of being simple, provides a complete description
of the composite Higgs physics. After constructing the model we present a first
analysis of its phenomenology, focusing on the structure of the Higgs
potential, on the constraints from the EWPT and on the spectrum of the new
particles.Comment: 42 pages, 10 figures; v2: minor changes and references added; v3:
version published in JHE
Discovery potential of top-partners in a realistic composite Higgs model with early LHC data
Composite Higgs models provide a natural, non-supersymmetric solution to the
hierarchy problem. In these models, one or more sets of heavy top-partners are
typically introduced. Some of these new quarks can be relatively light, with a
mass of a few hundred GeV, and could be observed with the early LHC collision
data expected to be collected during 2010. We analyse in detail the collider
signatures that these new quarks can produce. We show that final states with
two (same-sign) or three leptons are the most promising discovery channels.
They can yield a 5 sigma excess over the Standard Model expectation already
with the 2010 LHC collision data. Exotic quarks of charge 5/3 are a distinctive
feature of this model. We present a new method to reconstruct their masses from
their leptonic decay without relying on jets in the final state.Comment: 28 pages 11 Figures 7 Tables, minor changes, added references,
matches published versio
General Composite Higgs Models
We construct a general class of pseudo-Goldstone composite Higgs models,
within the minimal SO(5)/SO(4) coset structure, that are not necessarily of
moose-type. We characterize the main properties these models should have in
order to give rise to a Higgs mass around 125 GeV. We assume the existence of
relatively light and weakly coupled spin 1 and 1/2 resonances. In absence of a
symmetry principle, we introduce the Minimal Higgs Potential (MHP) hypothesis:
the Higgs potential is assumed to be one-loop dominated by the SM fields and
the above resonances, with a contribution that is made calculable by imposing
suitable generalizations of the first and second Weinberg sum rules. We show
that a 125 GeV Higgs requires light, often sub-TeV, fermion resonances. Their
presence can also be important for the models to successfully pass the
electroweak precision tests. Interestingly enough, the latter can also be
passed by models with a heavy Higgs around 320 GeV. The composite Higgs models
of the moose-type considered in the literature can be seen as particular limits
of our class of models.Comment: 51 pages, 12 figures, 5 appendices; v2: Corrected estimates of \delta
g_b in appendix B, references fixed, several minor improvements; v3: minor
improvements, to appear in JHE
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