394 research outputs found
Stuckelberg Axions and the Effective Action of Anomalous Abelian Models 1. A unitarity analysis of the Higgs-axion mixing
We analyze the quantum consistency of anomalous abelian models and of their
effective field theories, rendered anomaly-free by a Wess-Zumino term, in the
case of multiple abelian symmetries. These models involve the combined
Higgs-Stuckelberg mechanism and predict a pseudoscalar axion-like field that
mixes with the goldstones of the ordinary Higgs sector. We focus our study on
the issue of unitarity of these models both before and after spontaneous
symmetry breaking and detail the set of Ward identities and the organization of
the loop expansion in the effective theory. The analysis is performed on simple
models where we show, in general, the emergence of new effective vertices
determined by certain anomalous interactions.Comment: 67 pages, 26 figures, replaced with revised final version, to appear
on JHE
The Incidence of Trilateral Retinoblastoma : A Systematic Review and Meta-Analysis
PURPOSE: To estimate the incidence of trilateral retinoblastoma in patients with retinoblastoma. " DESIGN: Systematic review and meta-analysis. METHODS: We searched Medline and Embase for scientific literature published between January 1966 and July 2015 that assessed trilateral retinoblastoma incidence. We used a random-effects model for the statistical analyses. " RESULTS: We included 23 retinoblastoma cohorts from 26 studies. For patients with bilateral retinoblastoma the unadjusted chance of developing trilateral retinoblastoma across all cohorts was 5.3% (95% confidence interval [CI]: 3.3%-7.7%); the chance of pineal trilateral retinoblastoma was 4.2% (95% CI: 2.6%-6.2%) and the chance of nonpineal trilateral retinoblastoma was 0.8% (95% CI: 0.4%-1.3%). In patients with hereditary retinoblastoma (all bilateral cases, and the unilateral cases with a family history or germline RB1 mutation) we found a trilateral retinoblastoma incidence of 4.1% (95% CI: 1.9%-7.1%) and a pineal trilateral retinoblastoma incidence of 3.7% (95% CI: 1.8%-6.2%). To reduce the risk of overestimation bias we restricted analysis to retinoblastoma cohorts with a minimum size of 100 patients, resulting in adjusted incidences of 3.8% (95% CI: 2.4%-5.4%), 2.9% (95% CI: 1.9%-4.2%), and 0.7% (95% CI: 0.3%-1.2%) for any, pineal, and nonpineal trilateral retinoblastoma, respectively, among patients with bilateral retinoblastoma. Among hereditary retinoblastoma we found an adjusted trilateral retinoblastoma incidence of 3.5% (95% CI: 1.2%-6.7%) and a pineal trilateral retinoblastoma incidence of 3.2% (95% CI: 1.4%-5.6%). CONCLUSION: The estimated incidence of trilateral retinoblastoma is lower than what is reported in previous literature, especially after exclusion of small cohorts that were subject to overestimation bias in this context. (C) 2015 by Elsevier Inc. All rights reserved.)Peer reviewe
D-term inflation in non-minimal supergravity
D-term inflation is one of the most interesting and versatile models of
inflation. It is possible to implement naturally D-term inflation within high
energy physics, as for example SUSY GUTs, SUGRA, or string theories. D-term
inflation avoids the -problem, while in its standard form it always ends
with the formation of cosmic strings. Given the recent three-year WMAP data on
the cosmic microwave background temperature anisotropies, we examine whether
D-term inflation can be successfully implemented in non-minimal supergravity
theories. We show that for all our choices of K\"ahler potential, there exists
a parameter space for which the predictions of D-term inflation are in
agreement with the measurements. The cosmic string contribution on the measured
temperature anisotropies is always dominant, unless the superpotential coupling
constant is fine tuned; a result already obtained for D-term inflation within
minimal supergravity. In conclusion, cosmic strings and their r\^ole in the
angular power spectrum cannot be easily hidden by just considering a non-flat
K\"ahler geometry.Comment: 29 pages, 9 figures; minor changes to match publihed versio
High Scale Physics Connection to LHC Data
The existing data appears to provide hints of an underlying high scale
theory. These arise from the gauge coupling unification, from the smallness of
the neutrino masses, and via a non-vanishing muon anomaly. An overview of high
scale models is given with a view to possible tests at the Large Hadron
Collider. Specifically we discuss here some generic approaches to deciphering
their signatures. We also consider an out of the box possibility of a four
generation model where the fourth generation is a mirror generation rather than
a sequential generation. Such a scenario can lead to some remarkably distinct
signatures at the LHC.Comment: 23 pages, no figures. Based on invited lectures at the 46th Course at
the International School of Subnuclear Physics- Erice -Sicily: 29 August -7
September, 200
Hunting long-lived gluinos at the Pierre Auger Observatory
Eventual signals of split sypersymmetry in cosmic ray physics are analyzed in
detail. The study focusses particularly on quasi-stable colorless R-hadrons
originating through confinement of long-lived gluinos (with quarks,
anti-quarks, and gluons) produced in pp collisions at astrophysical sources.
Because of parton density requirements, the gluino has a momentum which is
considerable smaller than the energy of the primary proton, and so production
of heavy (mass ~ 500 GeV) R-hadrons requires powerful cosmic ray engines able
to accelerate particles up to extreme energies, somewhat above 10^{13.6} GeV.
Using a realistic Monte Carlo simulation with the AIRES engine, we study the
main characteristics of the air showers triggered when one of these exotic
hadrons impinges on a stationary nucleon of the Earth atmosphere. We show that
R-hadron air showers present clear differences with respect to those initiated
by standard particles. We use this shower characteristics to construct
observables which may be used to distinguish long-lived gluinos at the Pierre
Auger Observatory.Comment: 13 pages revtex, 9 eps figures. A ps version with high resolution
figures is available at
http://www.hep.physics.neu.edu/staff/doqui/rhadron_highres.p
Observing Brane Inflation
Linking the slow-roll scenario and the Dirac-Born-Infeld scenario of
ultra-relativistic roll (where, thanks to the warp factor, the inflaton moves
slowly even with an ultra-relativistic Lorentz factor), we find that the KKLMMT
D3/anti-D3 brane inflation is robust, that is, enough e-folds of inflation is
quite generic in the parameter space of the model. We show that the
intermediate regime of relativistic roll can be quite interesting
observationally. Introducing appropriate inflationary parameters, we explore
the parameter space and give the constraints and predictions for the
cosmological observables in this scenario. Among other properties, this
scenario allows the saturation of the present observational bound of either the
tensor/scalar ratio r (in the intermediate regime) or the non-Gaussianity f_NL
(in the ultra-relativistic regime), but not both.Comment: 31 pages, 12 figures; typo correcte
Screening for pineal trilateral retinoblastoma revisited: a meta-analysis
Topic To determine until what age children are at risk for pineal trilateral retinoblastoma (TRb), whether its onset is linked to the age at which intraocular retinoblastomas develop, and the lead time from a detectable pineal TRb to symptoms. Clinical relevance About 45% of patients with retinoblastoma – those with a germline RB1 pathogenic variant – are at risk for pineal TRb. Early detection and treatment is essential for survival. Current evidence is unclear on the usefulness of screening for pineal TRb and, if useful, until what age screening should be continued. Methods We conducted a study according to the MOOSE guideline for reporting meta-analyses of observational studies. We searched PubMed and Embase between January 1, 1966, and February 27, 2019, for published literature. We considered articles reporting patients with TRb with survival and follow-up data. Inclusion of articles was performed separately and independently by two authors, and two authors also independently extracted the relevant data. They resolved discrepancies by consensus. Results One hundred thirty-eight patients with pineal TRb were included. Of 22 asymptomatic patients, 21 (95%) were diagnosed before the age of 40 months (median 16, interquartile range 9–29). Age at diagnosis of pineal TRb in patients diagnosed with retinoblastoma at ≤6 months versus >6 months of age were comparable (P=0.44), suggesting independency between the ages at diagnosis of intraocular retinoblastoma and pineal TRb. The laterality of intraocular retinoblastoma and its treatment were unassociated with the age when the pineal TRb was diagnosed. The lead time from an asymptomatic to a symptomatic pineal TRb was approximately 1 year. By performing a screening magnetic resonance imaging scan every 6 months after the diagnosis of heritable retinoblastoma (median age 6 months) until the age of 36 months, at least 311 and 776 scans would be required to detect one asymptomatic pineal TRb and to save one life, respectively. Conclusion Patients with retinoblastoma are at risk for pineal trilateral retinoblastoma for a shorter period than previously assumed and the age at diagnosis of pineal trilateral retinoblastoma is independent of the age at diagnosis of retinoblastoma. The GRADE level of evidence for these conclusions remains low.Peer reviewe
Orientifolds, RG Flows, and Closed String Tachyons
We discuss the fate of certain tachyonic closed string theories from two
perspectives. In both cases our approach involves studying directly
configurations with finite negative tree-level cosmological constant. Closed
string analogues of orientifolds, which carry negative tension, are argued to
represent the minima of the tachyon potential in some cases. In other cases, we
make use of the fact, noted in the early string theory literature, that strings
can propagate on spaces of subcritical dimension at the expense of introducing
a tree-level cosmological constant. The form of the tachyon vertex operator in
these cases makes it clear that a subcritical-dimension theory results from
tachyon condensation. Using results of Kutasov, we argue that in some
Scherk-Schwarz models, for finely-tuned tachyon condensates, a minimal model
CFT times a subcritical dimension theory results. In some instances, these two
sets of ideas may be related by duality.Comment: 15 pages, 2 figures, uses harvmac; v2: references adde
Electrocardiographic parameters and the risk of new-onset atrial fibrillation in the general population:the Rotterdam Study
Aims We aimed to assess the (shape of the) association and sex differences in the link between electrocardiographic parameters and new-onset atrial fibrillation (AF). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methods A total of 12 212 participants free of AF at baseline from the population-based Rotterdam Study were included. Up to five and results repeated measurements of electrocardiographic parameters including PR, QRS, QT, QT corrected for heart rate (QTc), JT, RR interval, and heart rate were assessed at baseline and follow-up examinations. Cox proportional hazards- and joint models, adjusted for cardiovascular risk factors, were used to determine the (shape of the) association between baseline and longitudinal electrocardiographic parameters with new-onset AF. Additionally, we evaluated potential sex differences. During a median follow-up of 9.3 years, 1282 incident AF cases occurred among 12 212 participants (mean age 64.9 years, 58.2% women). Penalized cubic splines revealed that associations between baseline electrocardiographic measures and risk of new-onset AF were generally U- and N-shaped. Sex differences in terms of the shape of the various associations were most apparent for baseline PR, QT, QTc, RR interval, and heart rate in relation to new-onset AF. Longitudinal measures of higher PR interval [fully adjusted hazard ratio (HR), 95% confidence interval (CI), 1.43, 1.02–2.04, P = 0.0393] and higher QTc interval (fully adjusted HR, 95% CI, 5.23, 2.18–12.45, P = 0.0002) were significantly associated with new-onset AF, in particular in men . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusion Associations of baseline electrocardiographic measures and risk of new-onset AF were mostly U- and N-shaped. Longitudinal electrocardiographic measures of PR and QTc interval were significantly associated with new-onset AF, in particular among men.</p
How large could the R-parity violating couplings be?
We investigate in detail the predictions coming from the d=4 operators for
proton decay. We find the most general constraints for the R-parity violating
couplings coming from proton decay, taking into account all fermion mixing and
in different supersymmetric scenarios.Comment: 8 pages, several corrections, to appear in J.Phys.G (2005
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