3,784 research outputs found
Cosmological constraints on thermal relic axions and axion-like particles
Cosmological precision data can be used to set very strict constraints on
Axions and Axion-like particles (ALPs) produced thermally in the big bang. We
briefly review the known bounds and propose two new constraints for Axions and
ALPs decaying in the early universe, based upon the concomitant dilution of
baryon and neutrino densities, using WMAP7 and other cosmological data.Comment: 4 pages, 4 figures. To appear in the proceedings of 7th Patras
Workshop on Axions, WIMPs and WISPs, Mykonos, Greece, 26 June - 1 July 2011
and of TAUP 2011, Munich, Germany, 5 - 9 September 201
Cosmological bounds on pseudo Nambu-Goldstone bosons
We review the cosmological implications of a relic population of pseudo
Nambu-Goldstone bosons (pNGB) with an anomalous coupling to two photons, often
called axion-like particles (ALPs). We establish constraints on the pNGB mass
and two-photon coupling by considering big bang nucleosynthesis, the physics of
the cosmic microwave background, and the diffuse photon background. The bounds
from WMAP7 and other large-scale-structure data on the effective number of
neutrino species can be stronger than the traditional bounds from the
primordial helium abundance. These bounds, together with those from primordial
deuterium abundance, constitute the most stringent probes of early decays.Comment: 29 pages, 13 pictures. Enlarged discussions on BBN and recombination
constraints. One figure and several references added. Version accepted in
JCA
Relative Entropy of Coherent States on General CCR Algebras
For a subalgebra of a generic CCR algebra, we consider the relative entropy between a general (not necessarily pure) quasifree state and a coherent excitationthereof. We give a unified formula for this entropy in terms of single-particle modular data. Further, we investigate changes of the relative entropy along subalgebras arising from an increasing family of symplectic subspaces; here convexity of the entropy (as usually considered for the Quantum Null Energy Condition) is replaced with lower estimates for the second derivative, composed of âbulk termsâ and âboundary termsâ. Our main assumption is that the subspaces are in differential modular position, a regularity condition that generalizes the usual notion of half-sided modular inclusions. We illustrate our results in relevant examples, including thermal states for the conformal U(1)-current
An operator expansion for integrable quantum field theories
A large class of quantum field theories on 1+1 dimensional Minkowski space,
namely, certain integrable models, has recently been constructed rigorously by
Lechner. However, the construction is very abstract and the concrete form of
local observables in these models remains largely unknown. Aiming for more
insight into their structure, we establish a series expansion for observables,
similar but not identical to the well-known form factor expansion. This
expansion will be the basis for a characterization and explicit construction of
local observables, to be discussed elsewhere. Here, we establish the expansion
independent of the localization aspect, and analyze its behavior under
space-time symmetries. We also clarify relations with deformation methods in
quantum field theory, specifically, with the warped convolution in the sense of
Buchholz and Summers.Comment: minor corrections and clarifications, as published in J. Phys A; 24
page
Sport identification, moral perceptions and collective action: A study with young football players
We conducted a cross-sectional study investigating whether sport identification predicts different forms of collective action intentions aimed to redress the unfavourable condition faced by disadvantaged individuals. In doing so, moral perceptions (moral convictions, moral violation and moral obligation) were tested as mediators. Participants were young football players from the grassroots of a professional Italian club (N = 111). Results revealed that sport identification was indirectly associated with greater willingness to engage in both normative and non-normative solidarity-based collective action via stronger moral obligation perceptions; moral convictions mediated the relationship between sport identification and normative collective action, while no mediation effects emerged for moral violation. We discuss findings in relation to collective action and sport research
Cosmological bounds on sub-MeV mass axions
Axions with mass greater than 0.7 eV are excluded by cosmological precision
data because they provide too much hot dark matter. While for masses above 20
eV the axion lifetime drops below the age of the universe, we show that the
cosmological exclusion range can be extended from 0.7 eV till 300 keV,
primarily by the cosmic deuterium abundance: axion decays would strongly modify
the baryon-to-photon ratio at BBN relative to the one at CMB decoupling.
Additional arguments include neutrino dilution relative to photons by axion
decays and spectral CMB distortions. Our new cosmological constraints
complement stellar-evolution limits and laboratory bounds.Comment: 19 pages, 10 figure
InfoFaunaFVG: a novel progressive web application for wildlife surveillance
The Department of Agricultural, Food, Environmental and Animal Sciences (DI4A) at the University of Udine, in collaboration with Friuli Venezia Giulia regional authorities, within northeastern Italy, set up a wildlife monitoring and surveillance regional network, named InfoFaunaFVG. Here we describe the development and application of this data repository system based on a novel progressive web application, and report the data gathered in the first two and a half years of its use. InfoFaunaFVG is made of a Web Database and an integrated WebGIS system. In particular, the following open source softwares are used: Apache HTTP Server, Oracle MySQL, Symfony, Apache Tomcat, GeoServer, OpenLayers. The web app can be accessed from any web browser or by installing the progressive web application in the desktop or mobile devices. In short, operating from November 2019, InfoFaunaFVG currently (April 2022) contains a total of 40,175 records, from 300 different users, from 16 institutions. Among all species recorded, mammals were 40% (16,018) of the total, whereas avian species represented 59% (23,741), and others (reptiles and amphibians) 1% (416), respectively. Two hundred twenty-six different species (175 avian and 51 mammals) were recorded. Details about causes of death and live animal rescue were reported. To date, InfoFaunaFVG has proven to be a successful wildlife data repository system providing high quality consistent, accurate and traceable data. These had a considerable impact on regional wildlife governance. In the authorsâ knowledge, InfoFaunaFVG is the first example described in literature of such a progressive web application, coordinated on an institutional level, and not based on voluntary-citizen observations. InfoFaunaFVG has the potential to become the largest wildlife monitoring and surveillance data repository system on a national level
Preliminary non-invasive study of Roman glasses from Jesolo (Venice), Italy
Archaeological excavations at âLe Mureâ site (Jesolo, VE, Italy) have followed each other since the sixties, when the first evidence of an Early Medieval church (6thâ7th century AD) was found under the ruins of a Medieval Cathedral (11thâ12th AD). The last few years of investigations by CaâFoscari University have led to the collection of large amounts of glass fragments, including many tesserae, dating between the 4th and the 12th centuries AD. A selection of glass fragments and mosaic tesserae taken from the excavations performed in 2013â14 at this site were studied by means of reflectance spectroscopy in order to identify their chromophore ions, in particular Cu0, Cu2+, Co2+, Fe2+ and Fe3+, which were detected in both transparent and opaque samples. In addition, the use of high resolution close-up images allowed for the attribution of surface characteristics to specific manufacturing techniques, while glass chemistry was studied in order to group them into known compositional classes. This study, carried out by non-invasive analytical techniques
that allowed for the acquisition of preliminary data, will prove useful in driving further methodologies involving other non-invasive and micro-invasive analysis in order to obtain archaeometric information that can be related to concurrent archaeological results
Risalire il fiume. Cuoldi Ciastiel ad Andrazza e la tarda romanitĂ nell'alta valle del Tagliamento
L'articolo discute due contesti archeologici indagati dall'UniversitĂ Ca' Foscari: un castrum tardo romano e una necropoli di epoca altomedievale (VII secolo), ubicati nell'alta valle del Tagliamento (UD). Gli scavi sono stati eseguiti nel quadro di un progetto generale sulla transizione antichitĂ -medioevo in una vallata alpina. I risultati consentono di ricostruire, a grandi linee, le dinamiche del popolamento in un momento cruciale per la storia della valle e indicano nel VI secolo un momento di forte cesura
Asymmetric Dark Matter and Dark Radiation
Asymmetric Dark Matter (ADM) models invoke a particle-antiparticle asymmetry,
similar to the one observed in the Baryon sector, to account for the Dark
Matter (DM) abundance. Both asymmetries are usually generated by the same
mechanism and generally related, thus predicting DM masses around 5 GeV in
order to obtain the correct density. The main challenge for successful models
is to ensure efficient annihilation of the thermally produced symmetric
component of such a light DM candidate without violating constraints from
collider or direct searches. A common way to overcome this involves a light
mediator, into which DM can efficiently annihilate and which subsequently
decays into Standard Model particles. Here we explore the scenario where the
light mediator decays instead into lighter degrees of freedom in the dark
sector that act as radiation in the early Universe. While this assumption makes
indirect DM searches challenging, it leads to signals of extra radiation at BBN
and CMB. Under certain conditions, precise measurements of the number of
relativistic species, such as those expected from the Planck satellite, can
provide information on the structure of the dark sector. We also discuss the
constraints of the interactions between DM and Dark Radiation from their
imprint in the matter power spectrum.Comment: 22 pages, 5 figures, to be published in JCAP, minor changes to match
version to be publishe
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