9,708 research outputs found
Free Fields for Chiral 2D Dilaton Gravity
We give an explicit canonical transformation which transforms a generic
chiral 2D dilaton gravity model into a free field theory.Comment: LaTeX file, 4 pages, to appear in Phys. Rev.
Free fields via canonical transformations of matter-coupled 2D dilaton gravity models
It is shown that the 1+1-dimensional matter-coupled Jackiw-Teitelboim model
and the model with an exponential potential can be converted by means of
appropriate canonical transformations into a bosonic string theory propagating
on a flat target space with an indefinite signature. This makes it possible to
consistently quantize these models in the functional Schroedinger
representation thus generalizing recent results on CGHS theory.Comment: 15 pages, Late
Limits on excited tau leptons masses from leptonic tau decays
We study the effects induced by excited leptons on the leptonic tau decay at
one loop level. Using a general effective lagrangian approach to describe the
couplings of the excited leptons, we compute their contributions to the
leptonic decays and use the current experimental values of the branching ratios
to put limits on the mass of excited states and the substructure scale.Comment: 10 pages, 6 figures, to be published in Phys. Rev.
Kolmogorov analysis detecting radio and Fermi gamma-ray sources in cosmic microwave background maps
The Kolmogorov stochasticity parameter is shown to act as a tool to detect
point sources in the cosmic microwave background (CMB) radiation temperature
maps. Kolmogorov CMB map constructed for the WMAP's 7-year datasets reveals
tiny structures which in part coincide with point radio and Fermi/LAT gamma-ray
sources. In the first application of this method, we identified several sources
not present in the then available 0FGL Fermi catalog. Subsequently they were
confirmed in the more recent and more complete 1FGL catalog, thus strengthening
the evidence for the power of this methodology.Comment: 4 pages, 3 figs, 1 Table; to match the published versio
The actual Rees--Sciama effect from the Local Universe
Observations of the Cosmic Microwave Background (CMB) have revealed an
unexpected quadrupole-octopole alignment along a preferred axis pointing toward
the Virgo cluster. We here investigate whether this feature can be explained in
the framework of the concordance model by secondary anisotropies produced by
the non-linear evolution of the gravitational potential, the so-called
Rees-Sciama (RS) effect. We focus on the effect caused by the local
superclusters, which we calculate using a constrained high-resolution
hydrodynamical simulation, based on the IRAS 1.2-Jy all-sky galaxy redshift
survey, which reproduces the main structures of our Universe out to a distance
of 110 Mpc from our Galaxy. The resulting RS effect peaks at low multipoles and
has a minimum/maximum amplitude of -6.6\mu K 1.9\mu K. Even though its
quadrupole is well aligned with the one measured for the CMB, its amplitude is
not sufficient to explain the observed magnitude of the quadrupole/octopole
alignment. In addition, we analyze the WMAP-3 data with a linear matched filter
in an attempt to determine an upper limit for the RS signal amplitude on large
scales. We found that it is possible to infer a weak upper limit of 30\mu K for
its maximum amplitude.Comment: 7 pages, 4 figures, submitted to A&
Association of sociocultural stressors with bipolar disorder onset in Puerto Rican youth growing up as members of a minoritized ethnic group: results from the Boricua Youth Longitudinal Study
BACKGROUND: The development of bipolar disorder is currently explained by a complex interaction of genetic and environmental factors. Less is known regarding the influence of sociocultural factors. This study aims to evaluate the incidence and impact of sociocultural factors on bipolar disorder onset in two comparable samples of youth growing up in different social settings. METHODS: We leveraged data from two urban population-based cohorts representative of Puerto Rican children growing up in either San Juan (Puerto Rico) or the South Bronx (NYC) and followed up for 17 years. Bipolar disorder diagnoses were based on retrospective self-reports on the World Health Organization Composite International Diagnostic Interview. We used a causal inference approach to estimate associations of sociocultural factors with bipolar disorder onset after adjusting for potential confounders. FINDINGS: We found that South Bronx children, who grew up as a minoritized group, had twice the risk of bipolar disorder onset as young adults, with an incidence rate of 2.22 new cases per 1000 person-years compared to 1.08 new cases in San Juan (incidence rate difference, 1.13; 95% CI, 0.09-1.20). After adjusting for potential confounders, South Bronx children had the same lifetime hazard of bipolar disorder onset compared to San Juan children. However, our analysis demonstrated that caregivers' exposure to societal cultural stress partially explained the increased risk of bipolar disorder onset in the South Bronx, in addition to the potential contribution of genetics. INTERPRETATION: Our results provide evidence that societal cultural stress can increase the risk of lifetime bipolar disorder onset in youth growing up as a minoritized group. Addressing stress in minoritized groups might reduce the risk of bipolar disorder onset. FUNDING: The Boricua Youth Study has been supported by the National Institutes of HealthMH56401, MH098374, DA033172, and AA020191. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the article
Bounds for Lepton Flavor Violation and the Pseudoscalar Higgs in the General Two Higgs Doublet Model using muon factor
Current experimental data from the muon factor, seems to show the
necessity of physics beyond the Standard Model (SM), since the difference
between SM and experimental predictions is 2.6. In the framework of
the General Two Higgs Doublet Model (2HDM), we calculate the muon anomalous
magnetic moment to get lower and upper bounds for the Flavour Changing (FC)
Yukawa couplings in the leptonic sector. We also obtain lower bounds for the
mass of the pseudoscalar Higgs () as a function of the parameters of
the model.Comment: 12 pages, RevTex4, 5 figures. Improved presentation, updated
experimental data, amplified analysis, new figures added. Subbmited to Phys.
Rev.
Fine-to-Coarse Ranking in Ordinal and Imbalanced Domains: An Application to Liver Transplantation
Nowadays imbalanced learning represents one of the most vividly discussed challenges in machine learning. In these scenarios, one or some of the classes in the problem have a significantly lower a priori probability, usually leading to trivial or non-desirable classifiers. Because of this, imbalanced learning has been researched to a great extent by means of different approaches. Recently, the focus has switched from binary classification to other paradigms where imbalanced data also arise, such as ordinal classification. This paper tests the application of learning pairwise ranking with multiple granularity levels in an ordinal and imbalanced classification problem where the aim is to construct an accurate model for donor-recipient allocation in liver transplantation. Our experiments show that approaching the problem as ranking solves the imbalance issue and leads to a competitive performance
Black Hole Thermodynamics and Two-Dimensional Dilaton Gravity Theory
We relate various black hole solutions in the near-horizon region to black
hole solutions in two-dimensional dilaton gravity theories in order to argue
that thermodynamics of black holes in D>=4 can be effectively described by
thermodynamics of black holes in two-dimensional dilaton gravity theories. We
show that the Bekenstein-Hawking entropies of single-charged dilatonic black
holes and dilatonic p-branes with an arbitrary dilaton coupling parameter in
arbitrary spacetime dimensions are exactly reproduced by the Bekenstein-Hawking
entropy of the two-dimensional black hole in the associated two-dimensional
dilaton gravity model. We comment that thermodynamics of non-extreme stringy
four-dimensional black hole with four charges and five-dimensional black hole
with three charges may be effectively described by thermodynamics of the black
hole solutions with constant dilaton field in two-dimensional dilaton gravity
theories.Comment: 15 pages, LaTeX, added reference
Lepton Flavor Violation in the Two Higgs Doublet Model type III
We consider the Two Higgs Doublet Model (2HDM) of type III which leads to
Flavour Changing Neutral Currents (FCNC) at tree level in the leptonic sector.
In the framework of this model we can have, in principle, two situations: the
case (a) when both doublets acquire a vacuum expectation value different from
zero and the case (b) when only one of them is not zero. In addition, we show
that we can make two types of rotations for the flavor mixing matrices which
generates four types of lagrangians, with the rotation of type I we recover the
case (b) from the case (a) in the limit , and with the
rotation of type II we obtain the case (b) from (a) in the limit Moreover, two of the four possible lagrangians correspond to the models
of types I and II plus Flavor Changing (FC) interactions. The analitical
expressions of the partial lepton number violating widths and are derived for the cases (a) and (b) and both
types of rotations.In all cases these widths go asymptotically to zero in
the decoupling limit for all Higgses. We present from our analysis upper bounds
for the flavour changing transition and we show that such bounds
are sensitive to the VEV structure and the type of rotation utilized.Comment: 7 pages RevTeX4, 4 figures postscript, new section added and some new
reference
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