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 new physics interpretation of the IceCube data

IceCube has recently observed 37 events of TeV-PeV energies. The angular distribution, with a strong preference for downgoing directions, the spectrum, and the small muon to shower ratio in the data can not be accommodated assuming standard interactions of atmospheric neutrinos. We obtain an excellent fit, however, if a diffuse flux of ultrahigh energy (cosmogenic) neutrinos experiences collisions where only a small fraction of the energy is transferred to the target nucleon. We show that consistent models of TeV gravity or other non-Wilsonian completions of the standard model provide cross sections with these precise features. An increased statistics could clearly distinguish our scenario from the one assumed by IceCube (a diffuse flux of astrophysical neutrinos with a E^{-2} spectrum) and establish the need for new physics in the interpretation of the data.Comment: 13 pages, version to appear in Astroparticle Physic

Stabilizing strongly correlated photon fluids with non-Markovian reservoirs

We introduce a novel frequency-dependent incoherent pump scheme with a square-shaped spectrum as a way to study strongly correlated photons in arrays of coupled nonlinear resonators. This scheme can be implemented via a reservoir of population-inverted two-level emitters with a broad distribution of transition frequencies. Our proposal is predicted to stabilize a non-equilibrium steady state sharing important features with a zero-temperature equilibrium state with a tunable chemical potential. We confirm the efficiency of our proposal for the Bose-Hubbard model by computing numerically the steady state for finite system sizes: first, we predict the occurrence of a sequence of incompressible Mott-Insulator-like states with arbitrary integer densities presenting strong robustness against tunneling and losses. Secondly, for stronger tunneling amplitudes or non-integer densities, the system enters a coherent regime analogous to the superfluid state. In addition to an overall agreement with the zero-temperature equilibrium state, exotic non-equilibrium processes leading to a finite entropy generation are pointed out in specific regions of parameter space. The equilibrium ground state is shown to be recovered by adding frequency-dependent losses. The promise of this improved scheme in view of quantum simulation of the zero temperature many-body physics is highlighted

Phase diagram of incoherently driven strongly correlated photonic lattices

We explore theoretically the nonequilibrium photonic phases of an array of coupled cavities in presence of incoherent driving and dissipation. In particular, we consider a Hubbard model system where each site is a Kerr nonlinear resonator coupled to a two-level emitter, which is pumped incoherently. Within a Gutzwiller mean-field approach, we determine the steady-state phase diagram of such a system. We find that, at a critical value of the inter-cavity photon hopping rate, a second-order nonequilibrium phase transition associated with the spontaneous breaking of the $U(1)$ symmetry occurs. The transition from an incompressible Mott-like photon fluid to a coherent delocalized phase is driven by commensurability effects and not by the competition between photon hopping and optical nonlinearity. The essence of the mean-field predictions is corroborated by finite-size simulations obtained with matrix product operators and corner-space renormalization methods.Comment: 12 pages, 9 figure

Design of injection locked frequency divider in 65nm CMOS technology for mmW applications

In this paper, an Injection Locking Frequency Divider (ILFD) in 65 nm RF CMOS Technology for applications in millimeter-wave (mm-W) band is presented. The proposed circuit achieves 12.69% of locking range without any tuning mechanism and it can cover the entire mm-W band in presence of Process, Voltage and Temperature (PVT) variations by changing the Injection Locking Oscillator (ILO) voltage control. A design methodology flow is proposed for ILFD design and an overview regarding CMOS capabilities and opportunities for mm-W transceiver implementation is also exposed.Postprint (published version

An agent-based architecture for multifaceted online dispute resolution tools

The Twenty-fourth International Conference on Industrial, Engineering and Other Applications of Applied Intelligent Systems (IEA/AIE 2011), 2011Online Dispute Resolution (ODR) tools are being seen as a way to settle disputes out of courts, namely under virtual environments. However, the acceptance of these alternative methods is still relatively restricted, once existing tools are relatively undemanding and domain-centered. Indeed, there is the need for conceptual tools whose parts may be arranged for particular use, i.e., to operate in different domains. Following this line of attack, in this paper it will be presented a new agent-based approach to ODR. It comes in an abstract and formal form, in order to be independent of the legal domains, but specific enough to be applied to concrete ones. The main advantage is that functionality reuse is maximized, making architectures simpler to implement and to expandThe work described in this paper was developed under the TIARAC - Telematics and Artificial Intelligence in Alternative Conflict Resolution Project (PTDC/JUR/71354/2006), a research project supported by FCT (Science & Technology Foundation), Portugal

Incorporating stress estimation into user-centred agent-based platforms

Current virtual environments for communication, cooperation and problem solving lack the rich context information that is present in face-to-face interactions. People rely on this context information, that includes body language or level of stress just to name a few, to take decisions. In this paper we present an approach whose objective is to be able to acquire context information about the users of such technological tools, making that information available for the tool and eventually to other people. We present a prototype being developed in the context of an agent-based conflict resolution platform. As a result, we achieve communication and problem solving virtual environments that are richer and closer to traditional environments, allowing people and software agents to take better and more rational decisions

Using genetic algorithms to create solutions for conflict resolution

The process of devising solutions for conflict resolution generally configures a challenging task. There exist different approaches to address the problem, namely the use of case-based models or even relying on the parties themselves to perform the task. From a computational point of view, these problems generally represent a NP-complete problem. In order to surpass this shortcoming, in this paper it is presented a biologically inspired method to deal with the problem in which genetic algorithms are used to create possible solutions for a given dispute. The approach presented is able to generate a broad number of diverse solutions that cover virtually the whole search space for a given problem. This approach provides better results than a case-based approach since: (1) it is independent of the legal domain and (2) it does not depend on the number and quality of cases present in a database. The results of this work are being applied in a negotiation tool that is part of the UMCourt conflict resolution platform.The work described here was developed under the TIARAC-Telematics and Artificial Intelligence in Alternative Conflict Resolution research project (PTDC/JUR/71354/2006), a research project supported by FCT (Science & Technology Foundation), Portugal. The work of Davide Carneiro was supported by a doctoral grant, also by FCT (SFRH/BD/64890/2009)

Towards domain-independent conflict resolution tools

Given the current state of the legal systems, Online Dispute Resolution tools are being regarded as an alternative way to solve conflicts out of courts, namely under virtual environments. However, the use of these tools is still relatively restricted as they are still few in number and very domain-cantered. Indeed, abstract and conceptual tools whose building blocks could be adapted for particular use would foster the development of ODR systems. In this paper we present this novel line of attack, in which an agent-based architecture is used with the support of an ontology to build an abstract and formal ODR system, independent of the legal domains, but specific enough to be applied to concrete ones. Functionality reuse is maximized, making architectures simpler to implement and to expand.The work described in this paper was developed under the TIARAC - Telematics and Artificial Intelligence in Alternative Conflict Resolution Project (PTDC/JUR/71354/2006), a research project supported by FCT (Science & Technology Foundation), Portugal

CUTBUF: Buffer Management and Router Design for Traffic Mixing in VNET-Based NoCs

"© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works[EN] Router's buffer design and management strongly influence energy, area and performance of on-chip networks, hence it is crucial to encompass all of these aspects in the design process. At the same time, the NoC design cannot disregard preventing network-level and protocol-level deadlocks by devoting ad-hoc buffer resources to that purpose. In chip multiprocessor systems the coherence protocol usually requires different virtual networks (VNETs) to avoid deadlocks. Moreover, VNETutilization is highly unbalanced and there is no way to share buffers between them due to the need to isolate different traffic types. This paper proposes CUTBUF, a novel NoC router architecture to dynamically assign virtual channels (VCs) to VNETs depending on the actual VNETs load to significantly reduce the number of physical buffers in routers, thus saving area and power without decreasing NoC performance. Moreover, CUTBUF allows to reuse the same buffer for different traffic types while ensuring that the optimized NoC is deadlock-free both at network and protocol level. In this perspective, all the VCs are considered spare queues not statically assigned to a specific VNETand the coherence protocol only imposes a minimum number of queues to be implemented. Synthetic applications as well as real benchmarks have been used to validate CUTBUF, considering architectures ranging from 16 up to 48 cores. Moreover, a complete RTL router has been designed to explore area and power overheads. Results highlight how CUTBUF can reduce router buffers up to 33 percent with 2 percent of performance degradation, a 5 percent of operating frequency decrease and area and power saving up to 30.6 and 30.7 percent, respectively. Conversely, the flexibility of the proposed architecture improves by 23.8 percent the performance of the baseline NoC router when the same number of buffers is used.Zoni, D.; Flich Cardo, J.; Fornaciari, W. (2016). CUTBUF: Buffer Management and Router Design for Traffic Mixing in VNET-Based NoCs. IEEE Transactions on Parallel and Distributed Systems. 27(6):1603-1616. doi:10.1109/TPDS.2015.2468716S1603161627