Higgs couplings and new signals from Flavon-Higgs mixing effects within multi-scalar models

Testing the properties of the Higgs particle discovered at the LHC and searching for new physics signals, are some of the most important tasks of Particle Physics today. Current measurements of the Higgs couplings to fermions and gauge bosons, seem consistent with the Standard Model, and when taken as a function of the particle mass, should lay on a single line. However, in models with an extended Higgs sector the diagonal Higgs couplings to up-quarks, down-quarks and charged leptons, could lay on different lines, while non-diagonal flavor-violating Higgs couplings could appear too. We describe these possibilities within the context of multi-Higgs doublet models that employ the Froggatt-Nielsen (FN) mechanism to generate the Yukawa hierarchies. Furthermore, one of the doublets can be chosen to be of the inert type, which provides a viable dark matter candidate. The mixing of the Higgs doublets with the flavon field, can provide plenty of interesting signals, including: i) small corrections to the couplings of the SM-like Higgs, ii) exotic signals from the flavon fields, iii) new signatures from the heavy Higgs bosons. These aspects are studied within a specific model with 3+1 Higgs doublets and a singlet FN field. Constraints on the model are derived from the study of K and D mixing and the Higgs search at the LHC. For last, the implications from the latter aforementioned constraints to the FCNC top decay $t\to ch$ are presented too.Comment: 10 pages, 3 figures and 2 tables; v2: author added, text improved; v3: Title and Abstract slightly changed, 19 pages, references, tables and images added, additional clarifications; matches version published by Nucl. Phys.

Texture zeros and hierarchical masses from flavour (mis)alignment

We introduce an unconventional interpretation of the fermion mass matrix elements. As the full rotational freedom of the gauge-kinetic terms renders a set of infinite bases called weak bases, basis-dependent structures as mass matrices are unphysical. Matrix invariants, on the other hand, provide a set of basis-independent objects which are of more relevance. We employ one of these invariants to give a new parametrization of the mass matrices. By virtue of it, one gains control over its implicit implications on several mass matrix structures. The key element is the trace invariant which resembles the equation of a hypersphere with a radius equal to the Frobenius norm of the mass matrix. With the concepts of alignment or misalignment we can identify texture zeros with certain alignments whereas Froggatt-Nielsen structures in the matrix elements are governed by misalignment. This method allows further insights of traditional approaches to the underlying flavour geometry.Comment: 27 pages; v2 matches version accepted by NPB, discussion on Dirac CP phase for neutrinos adde

On the effectiveness of an optimization method for the traffic of TCP-based multiplayer online games

This paper studies the feasibility of using an optimization method, based on multiplexing and header compression, for the traffic of Massively Multiplayer Online Role Playing Games (MMORPGs) using TCP at the Transport Layer. Different scenarios where a number of flows share a common network path are identified. The adaptation of the multiplexing method is explained, and a formula of the savings is devised. The header compression ratio is obtained using real traces of a popular game and a statistical model of its traffic is used to obtain the bandwidth saving as a function of the number of players and the multiplexing period. The obtained savings can be up to 60 % for IPv4 and 70 % for IPv6. A Mean Opinion Score model from the literature is employed to calculate the limits of the multiplexing period that can be used without harming the user experience. The interactions between multiplexed and non-multiplexed flows, sharing a bottleneck with different kinds of background traffic, are studied through simulations. As a result of the tests, some limits for the multiplexing period are recommended: the unfairness between players can be low if the value of the multiplexing period is kept under 10 or 20 ms. TCP background flows using SACK (Selective Acknowledgment) and Reno yield better results, in terms of fairness, than Tahoe and New Reno. When UDP is used for background traffic, high values of the multiplexing period may stress the unfairness between flows if network congestion is severe

Tribological properties of plunging-type textured surfaces produced by modulation-assisted machining

Surface texturing technology has started to gain attention in the tribology community as a method for improving friction and lubrication ability of various mechanical components. Micro-sized depressions (e.g., grooves or dimples) on frictional surfaces act as fluid reservoirs and promote the retention of a lubricating thin film between mating components. Several fabrication techniques can be used to produce micro-dimple patterns on surfaces, but most of them show limitations when employed in practical efforts. The use of modulation-assisted machining (MAM) processes provides a cost-effective approach for creating surface textures over large areas that offers high control over the characteristic geometry of the textured surface. In this work, the effects of surface texturing and the influence of the dimensions of micro-sized depressions produced by MAM on wear performance are studied. Alloy 360 brass is mated with AISI 440C steel and studied using a ball-on-flat reciprocating configuration. Lubricated wear tests are carried out under conditions of variable frequency and normal load. The textured surfaces exhibited reduced wear under the highest frequency studied. The tribological performance of the surfaces is observed to depend on the size of the micro-dimples.The authors acknowledge financial support from the FEAD grant program at the Rochester Institute of Technology and from NSF grants CMMI 1130852 and 125481

Can a Wi-Fi WLAN support a first person shooter?

In corporate and commercial environments, the deployment of a set of coordinated Wi-Fi APs is becoming a common solution to provide Internet coverage to moving users. In these scenarios, real-time services as online games can also be present. This paper presents a set of experiments developed in a test scenario where an end device moves between different APs while generating game traffic. A WLAN solution based on virtual APs is used, in order to make the handoffs transparent for Layer 3. The results show that it is possible to maintain an acceptable level of subjective quality during the handoff. At the same time, it is set clear that the fact of having a gamer in an AP could be taken into account by radio resource management algorithms, in order to provide a better quality

Natural 2HDMs without FCNCs

Motivated by the fermion mass hierarchy we study the phenomenology of two flavorful two-Higgs-doublet model (2HDM) scenarios. By virtue of the flavor or singular alignment ansatz it is possible to link the mass of a subset of fermions to the vacuum-expectation-value (VEV) of a unique Higgs doublet and to simultaneously avoid flavor-changing-neutral-currents at tree-level. We explicitly construct two models called Type-A and B. There, either the top quark alone or all third generation fermions couple to the doublet with the larger VEV. The other fermions acquire their masses through the small VEV of the other doublet. Thus, more natural values for the Yukawa couplings can be obtained. The main differences between these models and conventional ones are studied including a discussion of both their structure and phenomenological consequences. In particular, as distinctive deviations for the Yukawa couplings of the light fermions are predicted we discuss possible tests at the LHC based on searches for $h\to J/\Psi + \gamma$, $h\to\mu\mu$, and heavy scalar resonances decaying to muon pairs. We find that for a wide region of parameter space this specific set of signatures can be used to distinguish among the new proposed types and the conventional ones