1,721,399 research outputs found
Stability and Efficiency of Directed Communication Networks
No full textThis paper analyzes the formation of directed networks where selfinterested individuals choose with whom they communicate. The focus of the paper is on whether the incentives of individuals to add or sever links will lead them to form networks that are efficient from a societal viewpoint. It is shown that for some contexts, to reconcile efficiency with individual incentives, benefits must either be redistributed in ways depending on “outsiders” who do not contribute to the productive value of the network, or in ways that violate equity (i.e., anonymity). It is also shown that there are interesting contexts for which it is possible to ensure that efficient networks are individually stable via (re)distributions that are balanced across components of the network, anonymous, and independent of the connections of non-contributing outsiders
On the Formation of Networks and Groups
No full textWe provide an introduction to and overview of the volume on Models of the Strategic Formation of Networks and Groups
Light higgsino dark matter from non-thermal cosmology
Full text linkWe study the scenario of higgsino dark matter in the context of a non-standard cosmology with a period of matter domination prior to Big Bang nucleosynthesis. Matter domination changes the dark matter relic abundance if it ends via reheating to a temperature below the higgsino thermal freeze-out temperature. We perform a model independent analysis of the higgsino dark matter production in such scenario. We show that light higgsino-type dark matter is possible for reheating temperatures close to 1 GeV. We study the impact of dark matter indirect detection and collider physics in this context. We show that Fermi-LAT data rule out non-thermal higgsinos with masses below 300 GeV. Future indirect dark matter searches from Fermi-LAT and CTA will be able to cover essentially the full parameter space. Contrary to the thermal case, collider signals from a 100 TeV collider could fully test the non-thermal higgsino scenario. In the second part of the paper we discuss the motivation of such non-thermal cosmology from the perspective of string theory with late-time decaying moduli for both KKLT and LVS moduli stabilisation mechanisms. We finally describe the impact of embedding higgsino dark matter in these scenarios
Enhancing the sensitivity to seesaw mechanism predictions in gauged <math display="inline"><mi>B</mi><mo>-</mo><mi>L</mi></math> scenarios
Full text linkNew gauge bosons coupled to heavy neutral leptons (HNLs) are simple and well-motivated extensions of the Standard Model. In searches for HNLs in proton fixed-target experiments, we find that a large population of gauge bosons (Z′) produced by proton bremsstrahlung may decay to HNLs, leading to a significant improvement in existing bounds on the (mHNL,Uα), where Uα represent the mixing between HNL and the active neutrinos with flavor α. We study this possibility in fixed target experiments with the 8 GeV proton beams, including SBND, MicroBooNE, and ICARUS, as well as DUNE and DarkQuest at 120 GeV. We find the projected sensitivities to additional Z′-mediated HNL production can bring the seesaw mechanism of the neutrino masses within a broadened experimental reach.New gauge bosons coupled to heavy neutral leptons (HNLs) are simple and well-motivated extensions of the Standard Model. In searches for HNLs in proton fixed-target experiments, we find that a large population of gauge bosons () produced by proton bremsstrahlung may decay to HNLs, leading to a significant improvement in existing bounds on the (), where represent the mixing between HNL and the active neutrinos with flavor . We study this possibility in fixed target experiments with the 8 GeV proton beams, including SBND, MicroBooNE, and ICARUS, as well as DUNE and DarkQuest at 120 GeV. We find the projected sensitivities to additional -mediated HNL production can bring the seesaw mechanism of the neutrino masses within a broadened experimental reach
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Power Suppression in D-Brane Inflation
Full text linkCosmological inflation is the period of rapid, accelerated expansion that occurred in the fraction of a second between the creation of spacetime and the Big Bang. Its proposal 35 years ago singlehandedly solved the three greatest issues of the Big Bang model . Now, researchers have found that certain inflation models may solve one more puzzle: the anomalous power-suppression at large angles in the cosmic microwave background (CMB). Despite consensus to the contrary, we argue that D-brane inflation is one such model. We show that there are initial conditions for which inflation deviates from ���slow-roll inflation��� dramatically enough to show adequate power-suppression in the CMB
A Study of Quintessential Inflation
Full text linkI present an analysis of a class of Dark Energy models called Quintessential Inflation Models. Such models are motivated by the common mathematical formalism describing the early expansion of the universe, i.e. inflation, and the late time accelerated expansion of space, i.e. quintessence. In particular, I examine the feasibility of such models and the ability of a subset of the proposed models in the literature to withstand the increasingly stringent conditions imposed by observational tests such as the Wilkinson Microwave Anisotropy Prove (WMAP) and the Supernova Legacy Survey
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