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

Market versus policy Europeanisation: has an imbalance grown over time? Bruegel Policy Contribution Issue #1 January 2020

This Policy Contribution tests the hypothesis that an imbalance has grown in Europe over the last few decades because markets have integrated to a greater extent than Europeanlevel policymaking, potentially creating difficulties for the democratic process in managing the economy. This hypothesis has been put forward by several authors but not so far tested empirically. To evaluate the process of European market integration – or market Europeanisation – over the last few decades, we assess intra-European trade and intra-European capital flows. Any estimate of policy integration, or Europeanisation, meanwhile, is fraught with difficulties and only proxies can be measured. Our preferred proxy is the number of employees of the European institutions and agencies relative to the aggregate number of public employees in national administrations in the European Union. The assumption is that European public employees generate, implement and oversee European policies and thus their relative number is a proxy for the development of European policies. An alternative indicator of policy Europeanisation is the relative frequency of European Union news in major national media outlets, as a proxy for the relevance to the public of European policies. Our results show that, measured by our proxies, policy Europeanisation has developed more rapidly than market Europeanisation, measured on the basis of both trade and capital flows. It is however also noted that the relative number of public employees has outpaced the relative frequency of European Union news in the media, possibly indicating a technocratic slant in policy Europeanisation. Further research could test the robustness of our results, in particular by using other measures of policy Europeanisation, such as the impact of European legislation on national laws and regulations

Hidden Photons from the Sun

A brief account of the phenomenon of photon oscillations into sub-eV mass hidden photons is given and used to estimate the flux and properties of these hypothetical particles from the Sun. A new generation of dedicated helioscopes, the Solar Hidden Photon Search (SHIPS) in the Hamburg Observatory amongst them, will cover a vast region of parameter space.Comment: 4 pages, contribution to 6th Patras Workshop on Axions, WIMPs and WISPs, Zurich University, Switzerland, 5-9 July 201

Characterization of local observables in integrable quantum field theories

Integrable quantum field theories in 1+1 dimensions have recently become amenable to a rigorous construction, but many questions about the structure of their local observables remain open. Our goal is to characterize these local observables in terms of their expansion coefficients in a series expansion by interacting annihilators and creators, similar to form factors. We establish a rigorous one-to-one characterization, where locality of an observable is reflected in analyticity properties of its expansion coefficients; this includes detailed information about the high-energy behaviour of the observable and the growth properties of the analytic functions. Our results hold for generic observables, not only smeared pointlike fields, and the characterizing conditions depend only on the localization region - we consider wedges and double cones - and on the permissible high energy behaviour.Comment: minor changes, as to appear in Commun. Math. Phys.; 39 pages, 4 figures, 1 vide

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

Feeling like a group after a natural disaster: Common ingroup identity and relations with outgroup victims among majority and minority young children

We conducted a field study to test whether the common ingroup identity model (Gaertner & Dovidio, 2000, reducing intergroup bias: The common ingroup identity model. Philadelphia, PA: Psychology Press) could be a useful tool to improve intergroup relations in the aftermath of a natural disaster. Participants were majority (Italian) and minority (immigrant) elementary school children (N = 517) living in the area struck by powerful earthquakes in May 2012. Results revealed that, among majority children, the perceived external threat represented by the earthquake was associated with greater perceptions of belonging to a common ingroup including both ingroup and outgroup. In turn, heightened one-group perceptions were associated with greater willingness to meet and help outgroup victims, both directly and indirectly via more positive outgroup attitudes. Among immigrant children, perceived disaster threat was not associated with any of the dependent variables; one-group perceptions were positively associated with outgroup attitudes, helping and contact intentions towards outgroup victims. Thus, onegroup perceptions after a natural disaster may promote more positive and supporting relations between the majority and the minority group. We discuss the theoretical and practical implications of the findings

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