The 130 GeV Fingerprint of Right-Handed Neutrino Dark Matter

Recently, an interesting indication for a dark matter signal in the form of a narrow line, or maybe two lines and/or an internal bremsstrahlung feature, has been found in data from the Fermi-LAT satellite detector. As recent analyses have also shown that there is little sign of extra contributions to continuum photons, it is natural to investigate leptophilic interacting massive particle (LIMP) models. We show that a model of radiatively generated neutrino masses may have the properties needed to explain the Fermi-LAT structure around 130 GeV. This model was proposed some 10 years ago, and predicted a clearly observable $\gamma$-ray signal in the Fermi-LAT (then GLAST) detector. Here, we update and improve that analysis, and show as an example that a right-handed neutrino of mass 135 GeV should give rise to three conspicuous effects: a broad internal bremsstrahlung bump with maximum around 120 GeV, a 2$\gamma$ line around 135 GeV, and a $Z\gamma$ line at 119.6 GeV (neglected in the previous work). These features together give a good fit to the 130 GeV structure, given the present energy resolution of the Fermi-LAT data. An attractive feature of the model is that the particle physics properties are essentially fixed, when relic density and mass of the right-handed neutrino dark matter particle have been set. Puzzling features of the data at present are a slight displacement of the signal from the galactic center, and a needed boost factor of order 5-15. This presents a challenge for numerical simulations including both baryons and dark matter on scales of 100 pc, and perhaps a need to go beyond the simplest halo models. With upcoming data, the double-peak structure with the two lines and the internal bremsstrahlung feature should be seen, if this model is correct. With the satellite GAMMA-400, a striking fingerprint of this dark matter candidate should then appear.Comment: 7 pages, 3 figure

Cohomology of moduli spaces of curves of genus three via point counts

In this article we consider the moduli space of smooth $n$-pointed non-hyperelliptic curves of genus 3. In the pursuit of cohomological information about this space, we make $\mathbb{S}_n$-equivariant counts of its numbers of points defined over finite fields for $n \leq 7$. Combining this with results on the moduli spaces of smooth pointed curves of genus 0, 1 and 2, and the moduli space of smooth hyperelliptic curves of genus 3, we can determine the $\mathbb{S}_n$-equivariant Galois and Hodge structure of the ($\ell$-adic respectively Betti) cohomology of the moduli space of stable curves of genus 3 for $n \leq 5$ (to obtain $n \leq 7$ we would need counts of ``8-pointed curves of genus 2'').Comment: 25 pages, shortened versio

Bootstrap Methods and Applications in Econometrics - A Brief Survey

This paper provides a brief survey of the bootstrap and its use in econometrics. As an introduction, the paper gives a description of the basics of the method, with a special emphasis on boostrap testing. A fairly large amount of space is devoted to discuss why bootstrap tests provide refinements compared to equivalent asymptotic tests. A series of recent different applications in the econometrics literature is then surveyed, in order to give a picture of this rapidly evolving research field.Bootstrap; Sample Reuse Methods; Simulation Methods

United Nations Territorial Administration and the Development of the Charter

The competition in sports equipment and sports fashion today is fierce. And as e-commerce grows, the competing players has to remain accessible and usable regard-less of the device their customers visit the website on. Stadium is Swedens biggest player on the market and puts a lot of effort on their online activity. Something Stadium found interesting was the possibility of introducing elements that would increase the conversion rates directly into the product menu. This study explores the possibility to find a responsive solution for the product menu at Stadiums’ e-commerce website which could contribute to increased conversion rates. The study is built upon an experiment and the foundations of the experiment is based upon a market analysis of used design patterns for product navigation in the domain of sport resellers. Added to that, theories of usability and sales aspects, Stadiums own point of view, and known design patterns, have all contributed to the birth of a responsive product navigation concept. What started as sketches first evolved into three high fidelity design solutions (one for desktop devices, one for tablet devices, and one for smartphone devices) and then into working prototypes. The prototypes were tested by multiple users, following a set of tasks. The results was then compared with the same tasks conducted at Stadiums current website. The theories we have found clearly indicate that a good user experience greatly affects the potential for higher conversion rates and also increase the possibility of a higher customer loyalty towards the brand. Stadiums’ philosophy is focused on the product range and to show the products as the hero of the brand. The user testing conducted showed that the design solutions made by us didn’t meet the standard of the current Stadium product navigation. The statistics from the tests is spraw-ling and the lack of completness within the prototype shined through. Despite the sprawling results, the study concludes in a design solution that can act as a starting point for further investigations to find the best possible solution

On the cohomology of the Losev-Manin moduli space

We determine the cohomology of the Losev-Manin moduli space of pointed genus zero curves as a representation of the product of symmetric groups.Comment: 10 pages, no figure. To appear in Manuscripta Mathematic

Detectability of a subdominant density component of cold dark matter

Here we examine the detectability of collisionless dark matter candidates that may constitute not all but only a subdominant component of galactic cold dark matter. We show that current axion searches are not suited for a subdominant component, while direct WIMP searches would not be severely affected by the reduced density. In fact, the direct detection rates of neutralinos stay almost constant even if neutralinos constitute 1% of the halo dark matter. Only for lower densities do the rates decrease with density. Even neutralinos accounting for only $10^{-4}$ of the local dark halo density are within proposed future discovery limits. We comment also on indirect WIMP searches.Comment: 11 pages, 3 figures (references added, minor rewriting

On the cohomology of moduli spaces of (weighted) stable rational curves

We give a recursive algorithm for computing the character of the cohomology of the moduli space \Mmb_{0,n} of stable $n$-pointed genus zero curves as a representation of the symmetric group \Sg_n on $n$ letters. Using the algorithm we can show a formula for the maximum length of this character. Our main tool is connected to the moduli spaces of weighted stable curves introduced by Hassett.Comment: Version 2: Several small changes. Details added in the proof of Theorem 5.1. Accepted for publication in Mathematische Zeitschrift. 14 page