4,657 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
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
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
Quantum backflow and scattering
Backflow is the phenomenon that the probability current of a quantum particle on the line can flow in the direction opposite to its momentum. In this article, previous investigations of backflow, pertaining to interaction-free dynamics or purely kinematical aspects, are extended to scattering situations in short-range potentials. It is shown that backflow is a universal quantum effect which exists in any such potential, and is always of bounded spatial extent in a specific sense. The effects of reflection and transmission processes on backflow are investigated, both analytically for general potentials, and numerically in various concrete examples
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
Hydrophobic cellulose-based and non-woven fabrics coated with mesoporous TiO2 and their virucidal properties under indoor light
Antiviral hydrophobic cellulose-based cotton or non-woven fabrics containing mesoporous TiO2 particles were developed for potential use in healthcare and in other contaminated environments. Hydrosols made with the sol-gel method using two different amounts of the Ti precursor were applied to cotton and non-woven fabrics and their virucidal effect on Murine Coronavirus (MHV-3) and Human Adenovirus (HAdV-5) was evaluated under indoor light irradiation. The results show 90% reduction of HAdV-5 and up to 99% of MHV-3 in non-woven fabric, and 90% reduction of MHV-3 and no reduction of HAdV-5 in cotton fabric. The antiviral activity was related to the properties of the TiO2 powders and coatings characterized by BET surface area, DRX, DLS, FTIR, DRS, SEM, TEM and water contact angle. The hydrophobic characteristic of the treated fabrics and the high surface area of the TiO2 particles favor interaction with the virus, especially MHV-3. These results demonstrate that non-woven fabric and cotton, coated with TiO2, can be highly effective in preventing contamination with MHV-3 and HAdV-5 viruses, particularly for applications in healthcare indoor environments
Care When It Counts: Establishing Trauma-Sensitive Care as a Preventative Approach for 0â3-Year-Old Children Suffering from Trauma and Chronic Stress
Adverse childhood experiences are an important societal concern. Children aged 0-3 are particularly vulnerable to unpredictable chronic stress due to the critical period for brain development and attachment. Trauma-sensitive care is a preventative approach to reduce the burden of stressful experiences by committing to positive relationships. Professional caregivers are ideally placed to offer trauma-sensitive care; however, earlier research reveals that the tools they need to consciously apply trauma-sensitive care principles are missing. The current study organized living labs (co-creative research method) to present trauma-sensitive care as a preventative approach aimed at children aged 0-3. Two living labs were organized in Belgium and Hungary, where professional caregivers collaborated to create a protocol that offers guidelines on how to implement trauma-sensitive care. The resulting protocol included a theoretical foundation on trauma as well as a translation of these guidelines into practical recommendations. The protocol was evaluated by incorporating it into a training intervention delivered to 100 professional caregivers from childcare organizations across four European countries. The protocol received positive feedback from participants, with results indicating a self-reported increase in knowledge, attitude and practice of trauma-sensitive care principles. We conclude that this trauma-sensitive care protocol is a promising answer to the needs of professional caregivers working with children aged 0-3
Resilience in children in the aftermath of disasters: a systematic review and a new perspective on individual, interpersonal, group, and intergroup level factors
Disasters can impact upon individuals, families, and communities in multiple ways. Research has mainly focused on risk and protective factors relating to the child (individual level) and the family (interpersonal level), not taking into account the processes at the level of social groups. The present review aims to (a) review psychological research on disasters determined by natural events in childhood, (b) distinguish individual, interpersonal, group, and intergroup levels, (c) emphasize the importance of considering resilience as a key outcome. We reviewed 294 studies (in addition to 28 reviewsâmetaâanalyses, and 29 naturalistic interventions), and identified factors at the individual (e.g., demographics, exposure, individual differences), interpersonal (e.g., parentâchild relationship, family and school environment), group (e.g., social identity, group membership), and intergroup (relations between different groups) levels. We argue that an integrated model of these factors and their interplay is needed to design interventions to enhance resilience in children and their communities. We extend previous theorizations by providing a wider conceptualization of distress and resilience, and by considering the interplay between factors at different levels. A multidimensional approach to the consequences of disasters in children is crucial to understand their development and wellâbeing, and to design effective interventions. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement
Run 2 Upgrades to the CMS Level-1 Calorimeter Trigger
The CMS Level-1 calorimeter trigger is being upgraded in two stages to
maintain performance as the LHC increases pile-up and instantaneous luminosity
in its second run. In the first stage, improved algorithms including
event-by-event pile-up corrections are used. New algorithms for heavy ion
running have also been developed. In the second stage, higher granularity
inputs and a time-multiplexed approach allow for improved position and energy
resolution. Data processing in both stages of the upgrade is performed with
new, Xilinx Virtex-7 based AMC cards.Comment: 10 pages, 7 figure
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