Hamiltonian reduction of SU(2) Dirac-Yang-Mills mechanics

The SU(2) gauge invariant Dirac-Yang-Mills mechanics of spatially homogeneous isospinor and gauge fields is considered in the framework of the generalized Hamiltonian approach. The unconstrained Hamiltonian system equivalent to the model is obtained using the gaugeless method of Hamiltonian reduction. The latter includes the Abelianization of the first class constraints, putting the second class constraints into the canonical form and performing a canonical transformation to a set of adapted coordinates such that a subset of the new canonical pairs coincides with the second class constraints and part of the new momenta is equal to the Abelian constraints. In the adapted basis the pure gauge degrees of freedom automatically drop out from the consideration after projection of the model onto the constraint shell. Apart from the elimination of these ignorable degrees of freedom a further Hamiltonian reduction is achieved due to the three dimensional group of rigid symmetry possessed by the system.Comment: 25 pages Revtex, no figure

Anderson localization in metamaterials and other complex media

We review some recent (mostly ours) results on the Anderson localization of light and electron waves in complex disordered systems, including: (i) left-handed metamaterials, (ii) magneto-active optical structures, (iii) graphene superlattices, and (iv) nonlinear dielectric media. First, we demonstrate that left-handed metamaterials can significantly suppress localization of light and lead to an anomalously enhanced transmission. This suppression is essential at the long-wavelength limit in the case of normal incidence, at specific angles of oblique incidence (Brewster anomaly), and in the vicinity of the zero-epsilon or zero-mu frequencies for dispersive metamaterials. Remarkably, in disordered samples comprised of alternating normal and left-handed metamaterials, the reciprocal Lyapunov exponent and reciprocal transmittance increment can differ from each other. Second, we study magneto-active multilayered structures, which exhibit nonreciprocal localization of light depending on the direction of propagation and on the polarization. At resonant frequencies or realizations, such nonreciprocity results in effectively unidirectional transport of light. Third, we discuss the analogy between the wave propagation through multilayered samples with metamaterials and the charge transport in graphene, which enables a simple physical explanation of unusual conductive properties of disordered graphene superlatices. We predict disorder-induced resonances of the transmission coefficient at oblique incidence of the Dirac quasiparticles. Finally, we demonstrate that an interplay of nonlinearity and disorder in dielectric media can lead to bistability of individual localized states excited inside the medium at resonant frequencies. This results in nonreciprocity of the wave transmission and unidirectional transport of light.Comment: 37 pages, 30 figures, Review pape

Unconstrained SU(2) Yang-Mills Quantum Mechanics with Theta Angle

The unconstrained classical system equivalent to spatially homogeneous SU(2) Yang-Mills theory with theta angle is obtained and canonically quantized. The Schr\"odinger eigenvalue problem is solved approximately for the low lying states using variational calculation. The properties of the groundstate are discussed, in particular its electric and magnetic properties, and the value of the "gluon condensate" is calculated. Furthermore it is shown that the energy spectrum of SU(2) Yang-Mills quantum mechanics is independent of the theta angle. Explicit evaluation of the Witten formula for the topological susceptibility gives strong support for the consistency of the variational results obtained.Comment: 20 pages REVTEX, no figures, one reference added, final version to appear in Phys. Rev.

Direct CP violation in radiative b decays in and beyond the Standard Model

We consider the partial rate asymmetry in the inclusive decay modes b to s gamma and b to d gamma, concentrating on non-standard models with new charged Higgs interactions. We find that the charged Higgs contribution to the asymmetry for b to s gamma is small in such models due to a universal cancellation mechanism. The asymmetry is therefore difficult to distinguish experimentally from the Standard Model (SM) value, which is also small. The cancellation mechanism is found to be rendered inoperative in supersymmetry due to the presence of chargino loops. Unlike b to s gamma, the rate asymmetry for b to d gamma in Higgs models can be quite different from its SM value, generally ranging from -20% to +20%. Specific model calculations are performed for the Three-Higgs Doublet Model and the ``Top'' Two-Higgs Doublet Model to serve as illustrations. We also offer some suggestions that may be helpful to experimentalists in the detection of the inclusive mode b to d gamma.Comment: RevTex, 24 pages, 6 figures, minor changes, version to appear in PR

The Impact of Flavour Changing Neutral Gauge Bosons on B->X_s gamma

The branching ratio of the rare decay B->X_s gamma provides potentially strong constraints on models beyond the Standard Model. Considering a general scenario with new heavy neutral gauge bosons, present in particular in Z' and gauge flavour models, we point out two new contributions to the B->X_s gamma decay. The first one originates from one-loop diagrams mediated by gauge bosons and heavy exotic quarks with electric charge -1/3. The second contribution stems from the QCD mixing of neutral current-current operators generated by heavy neutral gauge bosons and the dipole operators responsible for the B->X_s gamma decay. The latter mixing is calculated here for the first time. We discuss general sum rules which have to be satisfied in any model of this type. We emphasise that the neutral gauge bosons in question could also significantly affect other fermion radiative decays as well as non-leptonic two-body B decays, epsilon'/epsilon, anomalous (g-2)_mu and electric dipole moments.Comment: 31 pages, 5 figures; version published on JHEP; added magic QCD numbers for flavour-violating Z gauge boson contribution to B -> X_s gamm

Протезирование аортального клапана у больных пожилого и старческого возраста: анализ предоперационных факторов риска

Background. Despite an increase in the number of surgeries performed in elderly patients, conventional aortic valve replacement is associated with high postoperative mortality in comparison to young adults. The risk of surgical intervention in elderly patients is associated not only with the age, but also with the presence of a large number of concomitant diseases.Aim. To evaluate the immediate results of conventional aortic valve replacement and assess the impact of preoperative risk factors on surgical treatment.Methods. A retrospective analysis of the results of aortic valve replacement was performed in patients older than 65 years operated in the period from 2011 to 2015 (a total of 253 cases). The mean age of the patients was 70.4±4.14 years. The mean EuroSCORE was 6.09±4.45%. The impact of more than 30 preoperative risk factors on the in-hospital mortality and development of postoperative complications has been analyzed.Results. The overall in-hospital mortality was 10.3%. In-hospital mortality of isolated aortic valve replacement was 4.8%. In-hospital mortality of aortic valve replacement combined with coronary artery bypass grafting was 8.8%. High postoperative mortality rate was reliably associated with the urgency of surgery, a positive history of stroke, obesity, chronic renal failure, chronic obstructive pulmonary disease, pulmonary hypertension, a positive history of malignant neoplasms, polyvascular disease, pre-operative atrial fibrillation, IV class NYHA, post-stenotic aortic dilation, severe calcification, small aortic root.Conclusion. Aortic valve replacement in elderly and advanced age patients have relatively similar results to those of the younger patients. High risk of surgery in advanced age patients is mainly associated with the presence of concomitant extracardiac pathology and preoperative risk factors.Актуальность. Несмотря на увеличение количества операций у больных старшей возрастной категории, протезирование аортального клапана характеризуется высокой госпитальной летальностью по сравнению с более молодым контингентом больных. Риск хирургического вмешательства в группе пожилых пациентов связан не только с возрастом, но и с наличием большого количества сопутствующих заболеваний.Цель. Изучить непосредственные результаты протезирования аортального клапана и оценить степень влияния дооперационных факторов риска на показатели хирургического лечения.Материалы и методы. Проведен ретроспективный анализ результатов протезирования аортального клапана у больных старше 65 лет, прооперированных в период с 2011 по 2015 гг. (всего 253 случая). Средний возраст пациентов был 70,4±4,14 лет. Риск операции по шкале EuroSCORE составил 6,09±4,45%. Проанализировано влияние на показатели летальности и послеоперационных осложнений более 30 различных факторов риска.Результаты. Общая госпитальная летальность составила 10,3%. Летальность при изолированном протезировании аортального клапана была на уровне 4,8%, а при сопутствующем коронарном шунтировании – 8,8%. С послеоперационной летальностью статистически достоверно были связаны срочность хирургического вмешательства, наличие острого нарушения мозгового кровообращения в прошлом, ожирение, хроническая почечная недостаточность, хроническая обструктивная болезнь легких, легочная гипертензия, злокачественные новообразования в анамнезе, мультифокальный атеросклероз, дооперационная мерцательная аритмия, IV функциональный класс сердечной недостаточности по NYHA, постстенотическое расширение восходящей аорты, выраженный кальциноз и узкое фиброзное кольцо аортального клапана.Заключение. Протезирование аортального клапана у пациентов пожилого и старческого возраста продемонстрировало результаты, близкие к показателям более молодой категории больных. Высокий риск операции у возрастных пациентов обусловлен, главным образом, сопутствующей экстракардиальной патологией и предоперационными факторами риска

Topological Photonics

Topology is revolutionizing photonics, bringing with it new theoretical discoveries and a wealth of potential applications. This field was inspired by the discovery of topological insulators, in which interfacial electrons transport without dissipation even in the presence of impurities. Similarly, new optical mirrors of different wave-vector space topologies have been constructed to support new states of light propagating at their interfaces. These novel waveguides allow light to flow around large imperfections without back-reflection. The present review explains the underlying principles and highlights the major findings in photonic crystals, coupled resonators, metamaterials and quasicrystals.Comment: progress and review of an emerging field, 12 pages, 6 figures and 1 tabl

Goal-Directed Reasoning and Cooperation in Robots in Shared Workspaces: an Internal Simulation Based Neural Framework

From social dining in households to product assembly in manufacturing lines, goal-directed reasoning and cooperation with other agents in shared workspaces is a ubiquitous aspect of our day-to-day activities. Critical for such behaviours is the ability to spontaneously anticipate what is doable by oneself as well as the interacting partner based on the evolving environmental context and thereby exploit such information to engage in goal-oriented action sequences. In the setting of an industrial task where two robots are jointly assembling objects in a shared workspace, we describe a bioinspired neural architecture for goal-directed action planning based on coupled interactions between multiple internal models, primarily of the robot’s body and its peripersonal space. The internal models (of each robot’s body and peripersonal space) are learnt jointly through a process of sensorimotor exploration and then employed in a range of anticipations related to the feasibility and consequence of potential actions of two industrial robots in the context of a joint goal. The ensuing behaviours are demonstrated in a real-world industrial scenario where two robots are assembling industrial fuse-boxes from multiple constituent objects (fuses, fuse-stands) scattered randomly in their workspace. In a spatially unstructured and temporally evolving assembly scenario, the robots employ reward-based dynamics to plan and anticipate which objects to act on at what time instances so as to successfully complete as many assemblies as possible. The existing spatial setting fundamentally necessitates planning collision-free trajectories and avoiding potential collisions between the robots. Furthermore, an interesting scenario where the assembly goal is not realizable by either of the robots individually but only realizable if they meaningfully cooperate is used to demonstrate the interplay between perception, simulation of multiple internal models and the resulting complementary goal-directed actions of both robots. Finally, the proposed neural framework is benchmarked against a typically engineered solution to evaluate its performance in the assembly task. The framework provides a computational outlook to the emerging results from neurosciences related to the learning and use of body schema and peripersonal space for embodied simulation of action and prediction. While experiments reported here engage the architecture in a complex planning task specifically, the internal model based framework is domain-agnostic facilitating portability to several other tasks and platforms

Shape-Function Effects and Split Matching in B-> Xs l+ l-

We derive the triply differential spectrum for the inclusive rare decay B -> Xs l+ l- in the shape function region, in which Xs is jet-like with $mX^2 \lesssim mb \Lambda_QCD$. Experimental cuts make this a relevant region. The perturbative and non-perturbative parts of the matrix elements can be defined with the Soft-Collinear Effective Theory, which is used to incorporate alphas corrections consistently. We show that, with a suitable power counting for the dilepton invariant mass, the same universal jet and shape functions appear as in B-> Xs gamma and B-> Xu l nu decays. Parts of the usual alphas(m_b) corrections go into the jet function at a lower scale, and parts go into the non-perturbative shape function. For B -> Xs l+ l-, the perturbative series in alphas are of a different character above and below mu=mb. We introduce a ``split matching'' method that allows the series in these regions to be treated independently.Comment: 33 pages; journal versio

Beyond gene-disease validity: capturing structured data on inheritance, allelic-requirement, disease-relevant variant classes, and disease mechanism for inherited cardiac conditions

Background: As the availability of genomic testing grows, variant interpretation will increasingly be performed by genomic generalists, rather than domain-specific experts. Demand is rising for laboratories to accurately classify variants in inherited cardiac condition (ICC) genes, including secondary findings. Methods: We analyse evidence for inheritance patterns, allelic requirement, disease mechanism and disease-relevant variant classes for 65 ClinGen-curated ICC gene-disease pairs. We present this information for the first time in a structured dataset, CardiacG2P, and assess application in genomic variant filtering. Results: For 36/65 gene-disease pairs, loss of function is not an established disease mechanism, and protein truncating variants are not known to be pathogenic. Using the CardiacG2P dataset as an initial variant filter allows for efficient variant prioritisation whilst maintaining a high sensitivity for retaining pathogenic variants compared with two other variant filtering approaches. Conclusions: Access to evidence-based structured data representing disease mechanism and allelic requirement aids variant filtering and analysis and is a pre-requisite for scalable genomic testing