2,163 research outputs found
Gamma ray tests of Minimal Dark Matter
We reconsider the model of Minimal Dark Matter (a fermionic, hypercharge-less
quintuplet of the EW interactions) and compute its gamma ray signatures. We
compare them with a number of gamma ray probes: the galactic halo diffuse
measurements, the galactic center line searches and recent dwarf galaxies
observations. We find that the original minimal model, whose mass is fixed at
9.4 TeV by the relic abundance requirement, is constrained by the line searches
from the Galactic Center: it is ruled out if the Milky Way possesses a cuspy
profile such as NFW but it is still allowed if it has a cored one. Observations
of dwarf spheroidal galaxies are also relevant (in particular searches for
lines), and ongoing astrophysical progresses on these systems have the
potential to eventually rule out the model. We also explore a wider mass range,
which applies to the case in which the relic abundance requirement is relaxed.
Most of our results can be safely extended to the larger class of multi-TeV
WIMP DM annihilating into massive gauge bosons.Comment: 25 pages, 8 figures. v2: a few comments and references added, matches
version published on JCA
Be vicarious: the challenge for project management in the service economy
Purpose. The paper aims to answer to the following questions: which are the critical dynamic capabilities to survive in the rubber landscape of service economy? Does it exist in service economy a dynamic capabilities provider?
Methodology. The paper combines the literature review on dynamic capability perspective and that on vicariance to the Project Management professional services. Findings. Firstly, the paper identifies vicariance as an intriguing dynamic capability, crucial to survive in the rubber landscape of service economy. Secondly, the paper sheds light on Project Management (PM) as a vicarious that provides vicariance.
Practical implications. For each critical organizational dimension, the paper identifies the links among the service economy challenges and the vicariance typology required to the project manager to face those challenge.
Originality/value.The approach to conceive the PM as a vicarious that provides vicariance is original and leads to new insights on the professional services management. In fact, on one hand, dynamic capabilities cannot easily be bought through a market transaction; on the other hand, they must be built. This building can be achieved internally, by the organization itself (i.e. hierarchy), or through a partnership (i.e. hybrid form among hierarchy and market). PM professional services enrich organizations with additional information variety according to a hybrid (i.e. non- market) coordination model
The PMBOK standard evolution: leading the rising complexity
The aim of this work is to enlighten how the Standard for Project Management (part II of PMBOK® Guide) has evolved over the last 30 years as it has introjected the perspective of complexity. The several contexts (private firms, public institutions etc.) in which Project Management is applied become more and more complex (i.e. uncertain and characterized by unpredictable feedbacks among their own variables and their environments). This needs an enrichment (and perhaps a new conceptualization) of the endowment of information variety provided by the Standard for Project Management with respect to the specific requisite variety asked at a local level (i.e. the specific organizational contexts), to lead a project with efficiency, effectiveness and sustainability.
The traditional Standard for Project Management can no longer be considered as a “comfort zone” (i.e. a set of established and “familiar” frameworks, rules and tools aiming to ensure certain and predictable results). On the contrary, the Standard for Project Management should shift towards an open standard, that is able to consistently co-evolve with the increasingly complex contexts that even more ask for new tools, creative solutions and original combinations between exploitative and explorative knowledge
Homeopathic Dark Matter, or how diluted heavy substances produce high energy cosmic rays
We point out that current and planned telescopes have the potential of
probing annihilating Dark Matter (DM) with a mass of O(100) TeV and beyond. As
a target for such searches, we propose models where DM annihilates into lighter
mediators, themselves decaying into Standard Model (SM) particles. These models
allow to reliably compute the energy spectra of the SM final states, and to
naturally evade the unitarity bound on the DM mass. Indeed, long-lived
mediators may cause an early matter-dominated phase in the evolution of the
Universe and, upon decaying, dilute the density of preexisting relics thus
allowing for very large DM masses. We compute this dilution in detail and
provide results in a ready-to-use form. Considering for concreteness a model of
dark U(1) DM, we then study both dilution and the signals at various high
energy telescopes observing gamma rays, neutrinos and charged cosmic rays. This
study enriches the physics case of these experiments, and opens a new
observational window on heavy new physics sectors.Comment: 39 pages, 11 figures. v2: reference added, fixed technical issue
causing 2 figures not to show properly. v3: BBN constraints amended,
conclusions unchanged. Matches published versio
Asymmetric dark matter: residual annihilations and self-interactions
Dark matter (DM) coupled to light mediators has been invoked to resolve the
putative discrepancies between collisionless cold DM and galactic structure
observations. However, -ray searches and the CMB strongly constrain
such scenarios. To ease the tension, we consider asymmetric DM. We show that,
contrary to the common lore, detectable annihilations occur even for large
asymmetries, and derive bounds from the CMB, -ray, neutrino and
antiproton searches. We then identify the viable space for self-interacting DM.
Direct detection does not exclude this scenario, but provides a way to test it.Comment: 20 pages, 4 figure
Study of Cassini and New Horizons trajectories using JPL SPICE library
The obtaining of scientific data in interplanetary missions is based on a series of complex algorithms that serve to plan and develop the experiments.At different stages of the mission, due to the fact that the conditions planned to do each observation can end up not being the ones that actually happen, the best timing to carry out each observation must be recalculated.Therefore, the objective of this project is to understand and implement a subset of the algorithms used to obtain scientific data, using Matlab and SPICE, a library created by JPL, which is a software tool that contains a series of functions that are helpful when designing observations.In this project, a series of SPICE-based algorithms have been developed to calculate occultations, transit and the illumination of celestial bodies. Specifically,in this project are studied the flybys that were made by the probes: Cassini,Voyager and New Horizons, on the different planets for which they passed by. Forthe case of when Cassini flies over Jupiter, observations have been designed in two different ways; one considering whether the camera was pointing to the planet andthe other without taking it into account.The results obtained from the algorithms have been compared with the real trajectories already made, obtaining satisfactory results. It has also been proven from navigated images that the algorithms work correctly. Another algorithm has also been created to calculate the time interval during which the transit of a celestial body can be seen in front of another, from anyplanet. In particular, it has been tested with the transit that Mercury is going to make on November 11, 2019, achieving the expected result
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