109 research outputs found
A precise characterisation of the top quark electro-weak vertices at the ILC
Top quark production in the process at a future linear
electron positron collider with polarised beams is a powerful tool to determine
indirectly the scale of new physics. The presented study, based on a detailed
simulation of the ILD detector concept, assumes a centre-of-mass energy of
GeV and a luminosity of
equally shared between the incoming beam polarisations of . Events are selected in which the top pair
decays semi-leptonically and the cross sections and the forward-backward
asymmetries are determined. Based on these results, the vector, axial vector
and tensorial conserving couplings are extracted separately for the photon
and the component. With the expected precision, a large number of models
in which the top quark acts as a messenger to new physics can be distinguished
with many standard deviations. This will dramatically improve expectations from
e.g. the LHC for electro-weak couplings of the top quark.Comment: This work is an update of arXiv:1307.8102, minor changes w.r.t. v1
(typos, wrong grammar, incomplete sentences etc.
Symmetry Algebras in Chern-Simons Theories with Boundary: Canonical Approach
I consider the classical Kac-Moody algebra and Virasoro algebra in
Chern-Simons theory with boundary within the Dirac's canonical method and
Noether procedure. It is shown that the usual (bulk) Gauss law constraint
becomes a second-class constraint because of the boundary effect. From this
fact, the Dirac bracket can be constructed explicitly without introducing
additional gauge conditions and the classical Kac-Moody and Virasoro algebras
are obtained within the usual Dirac method. The equivalence to the symplectic
reduction method is presented and the connection to the Ba\~nados's work is
clarified. It is also considered the generalization to the
Yang-Mills-Chern-Simons theory where the diffeomorphism symmetry is broken by
the (three-dimensional) Yang-Mills term. In this case, the same Kac-Moody
algebras are obtained although the two theories are sharply different in the
canonical structures. The both models realize the holography principle
explicitly and the pure CS theory reveals the correspondence of the
Chern-Simons theory with boundary/conformal field theory, which is more
fundamental and generalizes the conjectured anti-de Sitter/conformal field
theory correspondence.Comment: 27 pages, No figures. Notes and references added. to appear in Nucl.
Phys.
PARTOS - Passive and Active Ray TOmography Software: description and preliminary analysis using TOMO-ETNA experiment’s dataset.
In this manuscript we present the new friendly seismic tomography software based on joint inversion of active and passive seismic sources called PARTOS (Passive Active Ray TOmography Software). This code has been developed on the base of two well-known widely used tomographic algorithms (LOTOS and ATOM-3D), providing a robust set of algorithms. The dataset used to set and test the program has been provided by TOMO-ETNA experiment. TOMO-ETNA database is a large, highquality dataset that includes active and passive seismic sources recorded during a period of 4 months in 2014. We performed a series of synthetic tests in order to estimate the resolution and robustness of the solutions. Real data inversion has been carried out using 3 different subsets: (i) active data; (ii) passive data; and (iii) joint dataset. Active database is composed by a total of 16,950 air-gun shots during 1 month and passive database includes 452 local and regional earthquakes recorded during 4
months. This large dataset provides a high ray density within the study region. The combination of active and passive seismic data, together with the high quality of the database, permits to obtain a new tomographic approach of the region under study never done before. An additional user-guide of PARTOS software is provided in order to facilitate the implementation for new users.PublishedS04351V. Storia e struttura dei sistemi vulcaniciJCR Journalope
Spin-transfer in an open ferromagnetic layer: from negative damping to effective temperature
Spin-transfer is a typical spintronics effect that allows a ferromagnetic
layer to be switched by spin-injection. Most of the experimental results about
spin transfer are described on the basis of the Landau-Lifshitz-Gilbert
equation of the magnetization, in which additional current-dependent damping
factors are added, and can be positive or negative. The origin of the damping
can be investigated further by performing stochastic experiments, like one shot
relaxation experiments under spin-injection in the activation regime of the
magnetization. In this regime, the N\'eel-Brown activation law is observed
which leads to the introduction of a current-dependent effective temperature.
In order to justify the introduction of these counterintuitive parameters
(effective temperature and negative damping), a detailed thermokinetic analysis
of the different sub-systems involved is performed. We propose a thermokinetic
description of the different forms of energy exchanged between the electric and
the ferromagnetic sub-systems at a Normal/Ferromagnetic junction. The
corresponding Fokker Planck equations, including relaxations, are derived. The
damping coefficients are studied in terms of Onsager-Casimir transport
coefficients, with the help of the reciprocity relations. The effective
temperature is deduced in the activation regime.Comment: 65 pages, 10 figure
Observational constraints on cosmic strings: Bayesian analysis in a three dimensional parameter space
Current data exclude cosmic strings as the primary source of primordial
density fluctuations. However, in a wide class of inflationary models, strings
can form at later stages of inflation and have potentially detectable
observational signatures. We study the constraints from WMAP and SDSS data on
the fraction of primordial fluctuations sourced by local cosmic strings. The
Bayesian analysis presented in this brief report is restricted to the minimal
number of parameters. Yet it is useful for two reasons. It confirms the results
of Pogosian et al (2003) using an alternative statistical method. Secondly, it
justifies the more costly multi-parameter analysis. Already, varying only three
parameters -- the spectral index and the amplitudes of the adiabatic and string
contributions -- we find that the upper bound on the cosmic string contribution
is of order 10%. We expect that the full multi-parameter study, currently
underway, will likely loosen this bound.Comment: v3: 4 pages, 5 figures, slight modifications to match published
versio
Microbiological and chemical monitoring of Marsala base wine obtained by spontaneous fermentation during large-scale production
The present work was undertaken to evaluate the effect of the natural winemaking on
the microbial and chemical composition of Marsala base wine. To this purpose, a
large-scale vinification process of Grillo grape cultivar was monitored from harvesting
to the final product. Total yeasts (TY) showed a rapid increase after must pressing and
reached values almost superimposable to those registered during the conventional
winemakings. Lactic acid bacteria (LAB) were registered at the highest levels
simultaneously to yeast growth at the beginning of the process. Saccharomyces
cerevisiae was the species found at the highest concentrations in all samples
analysed. Several strains (n= 16) was registered at high levels during the alcoholic
fermentation and/or aging of wine; only two of them were detected on the grape
surface. Lactobacillus plantarum was the LAB species most frequently isolated during
the entire vinification process. Ethanol content was approximately 14% (v/v) at the end
of vinification. The value of pH did not greatly vary during the process and the volatile
acidity (VA) was detected at low concentrations during the entire transformation. The
concentration of malic acid rapidly decreased during the AF; on the other hand, lactic
acid showed an irregular trend during the entire process. trans-caffeil tartaric acid was
the most abundant hydroxycinnamoyl tartaric acid and volatile organic compounds
(VOC) were mainly represented by isoamylic alcohol and isobutanol
Discovery of X-ray polarization angle rotation in active galaxy Mrk 421
The magnetic field conditions in astrophysical relativistic jets can be
probed by multiwavelength polarimetry, which has been recently extended to
X-rays. For example, one can track how the magnetic field changes in the flow
of the radiating particles by observing rotations of the electric vector
position angle . Here we report the discovery of a
rotation in the X-ray band in the blazar Mrk 421 at an average flux state.
Across the 5 days of Imaging X-ray Polarimetry Explorer (IXPE) observations of
4-6 and 7-9 June 2022, rotated in total by .
Over the two respective date ranges, we find constant, within uncertainties,
rotation rates ( and ) and polarization
degrees (). Simulations of a random walk of the
polarization vector indicate that it is unlikely that such rotation(s) are
produced by a stochastic process. The X-ray emitting site does not completely
overlap the radio/infrared/optical emission sites, as no similar rotation of
was observed in quasi-simultaneous data at longer wavelengths. We
propose that the observed rotation was caused by a helical magnetic structure
in the jet, illuminated in the X-rays by a localized shock propagating along
this helix. The optically emitting region likely lies in a sheath surrounding
an inner spine where the X-ray radiation is released
Evaluation of a real-time virtual intervention to empower persons living with HIV to use therapy self-management: study protocol for an online randomized controlled trial
Background: Living with HIV makes considerable demands on a person in terms of self-management, especially as regards adherence to treatment and coping with adverse side-effects. The online HIV Treatment, Virtual Nursing Assistance and Education (Virus de I'immunodeficience Humaine-Traitement Assistance Virtuelle Infirmiere et Enseignement; VIH-TAVIE (TM)) intervention was developed to provide persons living with HIV (PLHIV) with personalized follow-up and real-time support in managing their medication intake on a daily basis. An online randomized controlled trial (RCT) will be conducted to evaluate the efficacy of this intervention primarily in optimizing adherence to combination anti-retroviral therapy (ART) among PLHIV.Methods/design: A convenience sample of 232 PLHIV will be split evenly and randomly between an experimental group that will use the web application, and a control group that will be handed a list of websites of interest. Participants must be aged 18 years or older, have been on ART for at least 6 months, and have internet access. The intervention is composed of four interactive computer sessions of 20 to 30 minutes hosted by a virtual nurse who engages the PLHIV in a skills-learning process aimed at improving self-management of medication intake. Adherence constitutes the principal outcome, and is defined as the intake of at least 95% of the prescribed tablets. The following intermediary measures will be assessed: self-efficacy and attitude towards antiretroviral medication, symptom-related discomfort, and emotional support. There will be three measurement times: baseline (T0), after 3 months (T3) and 6 months (T6) of baseline measurement. The principal analyses will focus on comparing the two groups in terms of treatment adherence at the end of follow-up at T6. An intention-to-treat (ITT) analysis will be carried out to evaluate the true value of the intervention in a real context.Discussion: Carrying out this online RCT poses various challenges in terms of recruitment, ethics, and data collection, including participant follow-up over an extended period. Collaboration between researchers from clinical disciplines (nursing, medicine), and experts in behavioral sciences information technology and media will be crucial to the development of innovative solutions to supplying and delivering health services
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