Robust collider limits on heavy-mediator Dark Matter

We discuss how to consistently use Effective Field Theories (EFTs) to set universal bounds on heavy-mediator Dark Matter at colliders, without prejudice on the model underlying a given effective interaction. We illustrate the method for a Majorana fermion, universally coupled to the Standard Model quarks via a dimension-6 axial-axial four-fermion operator. We recast the ATLAS mono-jet analysis and show that a considerable fraction of the parameter space, seemingly excluded by a na\"ive EFT interpretation, is actually still unexplored. Consistently set EFT limits can be reinterpreted in any specific underlying model. We provide two explicit examples for the chosen operator and compare the reach of our model-independent method with that obtainable by dedicated analyses.Comment: 30 pages, 8 figures; v2: improved fig. 3, minor rephrasing, references added; v3: published versio

Scanning of the Supersymmetry Breaking Scale and the Gravitino Mass in Supergravity

We consider the minimal three-form ${\cal N}=1$ supergravity coupled to nilpotent three-form chiral superfields. The supersymmetry breaking is sourced by the three-forms of the chiral multiplets, while the value of the gravitino mass is controlled by the three-form of the supergravity multiplet. The three-forms can nucleate membranes which scan both the supersymmetry breaking scale and the gravitino mass. The peculiar supergravity feature that the cosmological constant is the sum of a positive contribution from the supersymmetry breaking scale and a negative contribution from the gravitino mass makes the cosmological constant jump. This can lead to a phenomenologically allowed small value of the cosmological constant even though the supersymmetry breaking scale and the gravitino mass are dynamically large.Comment: 18 pages, 2 figures, JHEP version, citations adde

Primordial Black Holes from Higgs Vacuum Instability: Avoiding Fine-tuning through an Ultraviolet Safe Mechanism

We have recently proposed the idea that dark matter in our universe is formed by primordial black holes generated by Standard Model Higgs fluctuations during inflation and thanks to the fact that the Standard Model Higgs potential develops an instability at a scale of the order of $10^{11}$ GeV. In this sense, dark matter does not need any physics beyond the Standard Model, although the mechanism needs fine-tuning to avoid the overshooting of the Higgs into the dangerous AdS vacuum. We show how such fine-tuning can be naturally avoided by coupling the Higgs to a very heavy scalar with mass $\gg 10^{11}$ GeV that stabilises the potential in the deep ultraviolet, but preserving the basic feature of the mechanism which is built within the Standard Model.Comment: 5 pages, 4 figure

A Cosmological Signature of the Standard Model Higgs Vacuum Instability: Primordial Black Holes as Dark Matter

For the current central values of the Higgs and top masses, the Standard Model Higgs potential develops an instability at a scale of the order of $10^{11}$ GeV. We show that a cosmological signature of such instability could be dark matter in the form of primordial black holes seeded by Higgs fluctuations during inflation. The existence of dark matter might not require physics beyond the Standard Model.Comment: 6+1 pages, 3 figures; v2: updated to the published PRL version, and added an Appendix about Non-Gaussian effect

On the publication and pagination of Ameghino's (1894) taxonomy of Santacrucian mammals

DURING the course of our research on the paleobiology and systematics ofmammalian remains of the Santa Cruz Formation of Argentine Patagonia,we becameaware of differences in the early literature dealing with Santacrucian (late Early Miocene) mammals. Although literature errors are not uncommon, they are often only an inconvenience. However, in this case it involves an article in which numerous taxa were erected, so that particular attention must be paid to the circumstances of its publication. The article in question is Florentino Ameghino?s (1894a, b) Énumération synoptique des espèces de mammifères fossiles des formations éocènes de Patagonie. This article was published formally in 1893 in the Boletín de la Academia Nacional de Ciencias en Córdoba and also in 1894, with identical title and text but different pagination, as an offprint.Fil: De Iuliis, Gerardo. University of Toronto; Canadá. Royal Ontario Museum; CanadáFil: Fernicola, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Racco, Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentin

The 750 GeV Diphoton excess, Dark Matter and Constraints from the IceCube experiment

Recent LHC data show hints of a new resonance in the diphoton distribution at an invariant mass of 750 GeV. Interestingly, this new particle might be both CP odd and play the role of a portal into the dark matter sector. Under these assumptions and motivated by the fact that the requirement of $SU(2)_L$ invariance automatically implies the coupling of this alleged new resonance to $ZZ$ and $Z\gamma$, we investigate the current and future constraints coming from the indirect searches performed through the neutrino telescope IceCube. We show that these constraints can be stronger than the ones from direct detection experiments if the dark matter mass is larger than a few hundred GeV. Furthermore, in the scenario in which the dark matter is a scalar particle, the IceCube data limit the cross section between the DM and the proton to values close to the predicted ones for natural values of the parameters.Comment: 20 pages, 6 figures; v2: added references; v3: published version, with some minor edits and including the exclusion bounds from searches of gamma ray

How Armenian Syrian Millennial Refugees use Social Media to Facilitate Integration into Canadian Society

Using a conceptual framework that builds on the constructs of community of practice (Homles & Meyerhoff, 1990; Lave & Wenger 1998; Wenger 1998) and superdiversity (Blommaert, 2013; Blommaert & Rampton, 2012; Jørgensen, Karrebæk, Madsen, & Møller, 2011; Vertovec, 2007), this study reports on the ways Armenian Syrian millennial refugees access information via social media. Findings are based on data collected through participant observations, interviews and survey protocols. The study showed the use of semiotic resources as social media allowed respondents to extend the social implicatures of language beyond their verbal proficiency levels