4,375 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
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
Olfactory neuroepithelium alterations and cognitive correlates in schizophrenia
BACKGROUND:
Few studies have investigated alterations of olfactory neuroepithelium (ONE) as a biomarker of schizophrenia, and none its association with cognitive functioning.
METHOD:
Fresh ONE cells from twelve patients with schizophrenia and thirteen healthy controls were collected by nasal brushing, cultured in proper media and passed twelve times. Markers of cell proliferation (BrdU incorporation, Cyclin-D1 and p21 protein level) were quantified.Cognitive function was measured using Brief Neuropsychological Examination-2.
PRIMARY OUTCOME:
proliferation of ONE cells from schizophrenic patients at passage 3. Secondary outcome: association between alteration of cell proliferation and cognitive function.
RESULTS:
Fresh ONE cells from patients showed a faster cell proliferation than those from healthy controls at passage 3. An opposite trend was observed at passage 9, ONE cells of patients with schizophrenia showing slower cell proliferation as compared to healthy controls. In schizophrenia, overall cognitive function (Spearman's rho -0.657, p\u202f<\u202f0.01), verbal memory - immediate recall, with interference at 10\u202fs and 30\u202fs (Spearman's rho from -0.676 to 0.697, all p\u202f<\u202f0.01) were inversely associated with cell proliferation at passage 3.
CONCLUSION:
Fresh ONE cells collected by nasal brushing might eventually represent a tool for diagnosing schizophrenia based upon markers of cell proliferation, which can be easily implemented as single-layer culture. Cell proliferation at passage 3 can be regarded as a promising proxy of cognitive functioning in schizophrenia. Future studies should replicate these findings, and may assess whether ONE alterations are there before onset of psychosis, serving as an early sign in patients with at risk mental state
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