Unitary Approach Research Articles

Study of Ds+→K+K−π+ decay

We investigate the $D_{s}^{+} \rightarrow K^{+} K^{-} \pi^{+}$ decay theoretically with the final state interactions, which is based on the chiral unitary approach and takes into account the external and internal $W$-emission mechanisms at the quark level. Only considering three resonances contributions, the $f_0(980)$ in $S$-wave, the $\bar {K}^{*}(892)^{0}$ and $\phi(1020)$ in $P$-wave, one can make a good description of the recent experimental data from BESIII Collaboration, where the contribution from $S$-wave is found to be small. Besides, we also make a calculation of the corresponding branching fractions, which are consistent with the results of BESIII Collaboration and Particle Data Group.

Refinements of Huygens-Wilker-Lazarovic inequalities via the hyperbolic cosine polynomials

The aim of this paper is to provide new refinements of Huygens-Wilker-Lazarovic inequalities using hyperbolic cosine polynomials. We give an unitary approach for both inequalities of trigonometric and hyperbolic functions.

Excessive Worrying as a Central Feature of Anxiety during the First COVID-19 Lockdown-Phase in Belgium: Insights from a Network Approach.

Since the WHO declared the COVID-19 pandemic on March 11, 2020, the novel coronavirus, SARS-CoV-2, has profoundly impacted public health and the economy worldwide. But there are not the only ones to be hit. The COVID-19 pandemic has also substantially altered mental health, with anxiety symptoms being one of the most frequently reported problems. Especially, the number of people reporting anxiety symptoms increased significantly during the first lockdown-phase compared to similar data collected before the pandemic. Yet, most of these studies relied on a unitary approach to anxiety, wherein its different constitutive features (i.e., symptoms) were tallied into one sum-score, thus ignoring any possibility of interactions between them. Therefore, in this study, we seek to map the associations between the core features of anxiety during the first weeks of the first Belgian COVID-19 lockdown-phase (n = 2,829). To do so, we implemented, in a preregistered fashion, two distinct computational network approaches: a Gaussian graphical model and a Bayesian network modelling approach to estimate a directed acyclic graph. Despite their varying assumptions, constraints, and computational methods to determine nodes (i.e., the variables) and edges (i.e., the relations between them), both approaches pointed to excessive worrying as a node playing an especially influential role in the network system of the anxiety features. Altogether, our findings offer novel data-driven clues for the ongoing field’s larger quest to examine, and eventually alleviate, the mental health consequences of the COVID-19 pandemic.

Quantum Approach to Damped Three Coupled Nano-Optomechanical Oscillators

We investigate quantum features of three coupled dissipative nano-optomechanical oscillators. The Hamiltonian of the system is somewhat complicated due not only to the coupling of the optomechanical oscillators but to the dissipation in the system as well. In order to simplify the problem, a spatial unitary transformation approach and a matrix-diagonalization method are used. From such procedures, the Hamiltonian is eventually diagonalized. In other words, the complicated original Hamiltonian is transformed to a simple one which is associated to three independent simple harmonic oscillators. By utilizing such a simplification of the Hamiltonian, complete solutions (wave functions) of the Schrödinger equation for the optomechanical system are obtained. We confirm that the probability density converges to the origin of the coordinate in a symmetric manner as the optomechanical energy dissipates. The wave functions that we have derived can be used as a basic tool for evaluating diverse quantum consequences of the system, such as quadrature fluctuations, entanglement entropy, energy evolution, transition probability, and the Wigner function.

Locating Ruelle–Pollicott resonances* *This work was partially supported by the PRIN Grant ‘Regular and stochastic behaviour in dynamical systems’ (PRIN 2017S35EHN). LC and OB acknowledge the MIUR Excellence Department Project awarded to the Department of Mathematics, University of Rome Tor Vergata, CUP E83C18000100006. We thank Péter Bálint, Viviane Baladi, Oscar Bandtlow, Giovanni Forni, Stefano Galatolo, Daniele Galli, Thomas Gilbert, Marco

We study the spectrum of transfer operators associated to various dynamical systems. Our aim is to obtain precise information on the discrete spectrum. To this end we propose a unitary approach. We consider various settings where new information can be obtained following different branches along the proposed path. These settings include affine expanding Markov maps, uniformly expanding Markov maps, non-uniformly expanding or simply monotone maps, hyperbolic diffeomorphisms. We believe this approach could be greatly generalised.

Prediction of neutron electromagnetic form factors behaviors just by the proton electromagnetic form factors data

First time a theoretical prediction of the neutron electromagnetic form factors behaviors in the whole region of their definition by the use of the proton electromagnetic form factors data only is demonstrated. This could be achieved in the framework of the unitary and analytic approach to a description of the nucleon electromagnetic form factors with canonical normalization conditions, the QCD (up to the logarithmic correction) asymptotic behaviors and specific transformation properties of the nucleon electromagnetic current in the isotopic space.

Cooperative differential games guidance laws for multiple attackers against an active defense target

This paper is concerned with a scenario of multiple attackers trying to intercept a target with active defense. Three types of agents are considered in the guidance: The multiple attackers, the target and the defender, where the attackers aim to pursuit the target from different directions and evade from the defender simultaneously. The guidance engagement is formulated in the framework of a zero-sum two-person differential game between the two opposing teams, such that the measurements on the maneuver of the target or estimations on the defending strategy of the defender can be absent. Cooperation of the attackers resides in two aspects: redundant interception under the threat of the defender and the relative intercept geometry with the target. The miss distances, the relative intercept angle errors and the costs of the agents are combined into a single performance index of the game. Such formulation enables a unitary approach to the design of guidance laws for the agents. To minimize the control efforts and miss distances for the attackers, an optimization method is proposed to find the best anticipated miss distances to the defender under the constraint that the defender is endowed with a capture radius. Numerical simulations with two cases are conducted to illustrate the effectiveness of the proposed cooperative guidance law.

Public Interest as a Basis for Planning Standards in Urban Development: State-Socialist and Post-socialist Cases in Serbia

How public interest is constituted in planning practice varies according to the local context. Using state-socialist and post-socialist cases in Belgrade, Serbia, we explore the shift in the realization of public interest as a basis for planning standards regarding provision of public land use and services. The research looks at trends for planning standards on two case studies, and reveals the underlying norms of this local interpretation of public interest via interviews with planning professionals and residents. The results suggest not only the persistence of the top-down unitary approach to public interest in planning but also a deterioration in prescribed standards.

Unitarity bounds for semileptonic decays in lattice QCD

In this work we discuss in detail the nonperturbative determination of the momentum dependence of the form factors entering in semileptonic decays using unitarity and analyticity constraints. The method contains several new elements with respect to previous proposals and allows to extract, using suitable two-point functions computed nonperturbatively, the form factors at low momentum transfer ${q}^{2}$ from those computed explicitly on the lattice at large ${q}^{2}$, without any assumption about their ${q}^{2}$-dependence. The approach will be very useful for exclusive semileptonic $B$-meson decays, where the direct calculation of the form factors at low ${q}^{2}$ is particularly difficult due to large statistical fluctuations and discretization effects. As a testing ground we apply our approach to the semileptonic $D\ensuremath{\rightarrow}K\ensuremath{\ell}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ decay, where we can compare the results of the unitarity approach to the explicit direct lattice calculation of the form factors in the full ${q}^{2}$-range. We show that the method is very effective and that it allows to compute the form factors with rather good precision.

The a0(980) and f0(980) in the process [formula omitted

In this work, we have investigated the process Ds+→K+K−π+, taking into account the contributions from the S-wave pseudoscalar-pseudoscalar interaction within the chiral unitary approach, and also the intermediate ϕ resonance. By analyzing the BESIII and BABAR measurements, we conclude that the f0(980) state, dynamically generated from the S-wave pseudoscalar-pseudoscalar interaction, gives the dominant contribution close to the K+K− threshold in the K+K− invariant mass distribution of the decay Ds+→K+K−π+ in S-wave. On the other hand, our results imply that the lineshape adopted by BESIII and BABAR for the resonances a0(980) and f0(980) is not advisable in the fit to the data close to the K+K− threshold.

Spin-Pure Stochastic-CASSCF via GUGA-FCIQMC Applied to Iron-Sulfur Clusters.

In this work, we demonstrate how to efficiently compute the one- and two-body reduced density matrices within the spin-adapted full configuration interaction quantum Monte Carlo (FCIQMC) method, which is based on the graphical unitary group approach (GUGA). This allows us to use GUGA-FCIQMC as a spin-pure configuration interaction (CI) eigensolver within the complete active space self-consistent field (CASSCF) procedure and hence to stochastically treat active spaces far larger than conventional CI solvers while variationally relaxing orbitals for specific spin-pure states. We apply the method to investigate the spin ladder in iron–sulfur dimer and tetramer model systems. We demonstrate the importance of the orbital relaxation by comparing the Heisenberg model magnetic coupling parameters from the CASSCF procedure to those from a CI-only (CASCI) procedure based on restricted open-shell Hartree–Fock orbitals. We show that the orbital relaxation differentially stabilizes the lower-spin states, thus enlarging the coupling parameters with respect to the values predicted by ignoring orbital relaxation effects. Moreover, we find that, while CASCI results are well fit by a simple bilinear Heisenberg Hamiltonian, the CASSCF eigenvalues exhibit deviations that necessitate the inclusion of biquadratic terms in the model Hamiltonian.

Parameter-dependent unitary transformation approach for quantum Rabi model

Quantum Rabi model has been exactly solved by employing the parameter-dependent unitary transformation method in both the occupation number representation and the Bargmann space. The analytical expressions for the complete energy spectrum consisting of two double-fold degenerate sub-energy spectra are presented in the whole range of all the physical parameters. Each energy level is determined by a parameter in the unitary transformation, which obeys a highly nonlinear equation. The corresponding eigenfunction is a convergent infinite series in terms of the physical parameters. Due to the level crossings between the neighboring eigenstates at certain physical parameter values, such the degeneracies could lead to novel physical phenomena in the two-level system with the light–matter interaction.

Quality Assurance Framework in Technical and Vocational Education and Training: A Comparative Study of Nigeria, Malaysia and UK

This study aims to compare the technical vocational education and training quality assurance framework of Nigeria, Malaysia and the United Kingdom. The study adopted a qualitative method document analysis to elicit information to compare quality assurance frameworks of Nigeria, Malaysia and the United Kingdom in the context of the technical vocational education and training systems. The study revealed current practices of quality assurance frameworks of Nigeria, Malaysia and the United Kingdom. The framework's emphasis on appropriately skilled workforce needed for socio-economic development and sets a benchmark for consistency to promote trust. The study also revealed similarities as a commitment to evidence-based decision making for continuous quality improvement while the difference in quality assurance frameworks of Nigeria and Malaysia is revealed based on the government-led approach and the United Kingdom operates based on a unitary approach. The study also revealed suitable quality assurance framework components as follows: integrated planning, integrated reviewing and management. This study discussed reforms needed of quality assurance framework in technical vocational education and training system and suggested that Nigerian government needed to encourage her technical vocational education and training system for the desired objectives through quality assurance framework.

Study the B^{0}_{(s)} decays into phi and a scalar or vector meson

In the present work, we investigate the decays of B^{0}_{(s)} rightarrow phi pi ^{+}pi ^{-} with the final state interaction based on the chiral unitary approach. In the final state interaction of the pi ^+pi ^- with its coupled channels, we study the effects of the eta eta channel in the two-body interaction for the reproduction of the f_{0}(980) state, where its contribution to the f_{0}(980) state can be ignored. Our results for the pi ^+pi ^- invariant mass distributions of the decay B^{0}_{s} rightarrow phi pi ^{+}pi ^{-} describe the experimental data up to 1 GeV well, with the resonance contributions from the f_{0}(980) and rho . For the predicted invariant mass distributions of the B^{0} rightarrow phi pi ^{+}pi ^{-} decay, we find that the contributions from the f_{0}(500) are significant, but not from the f_{0}(980) state. With some experimental branching ratios to determine the production vertex factors, we make predictions for the branching ratios of the other decay channels, including the vector mesons, in the B^0_{(s)} decays, some of which are consistent with the experimental measurements within the uncertainties.

Deep Learning Application for Analyzing of Constituents and Their Correlations in the Interpretations of Medical Images.

The need for time and attention, given by the doctor to the patient, due to the increased volume of medical data to be interpreted and filtered for diagnostic and therapeutic purposes has encouraged the development of the option to support, constructively and effectively, deep learning models. Deep learning (DL) has experienced an exponential development in recent years, with a major impact on interpretations of the medical image. This has influenced the development, diversification and increase of the quality of scientific data, the development of knowledge construction methods and the improvement of DL models used in medical applications. All research papers focus on description, highlighting, classification of one of the constituent elements of deep learning models (DL), used in the interpretation of medical images and do not provide a unified picture of the importance and impact of each constituent in the performance of DL models. The novelty in our paper consists primarily in the unitary approach, of the constituent elements of DL models, namely, data, tools used by DL architectures or specifically constructed DL architecture combinations and highlighting their “key” features, for completion of tasks in current applications in the interpretation of medical images. The use of “key” characteristics specific to each constituent of DL models and the correct determination of their correlations, may be the subject of future research, with the aim of increasing the performance of DL models in the interpretation of medical images.

Edge counts for the auxiliary pair graph within the graphical unitary group approach

Closed-form expressions are presented for the numbers of edges in the auxiliary pair graphs (APGs) associated with non spin–orbit and spin–orbit Shavitt graphs for full configuration interaction expansions. A Shavitt graph is a visual representation of a configuration state function expansion space constructed via the graphical unitary group approach (GUGA). An APG is an organisational aid and a programmatic tool generated from a Shavitt graph. The number of edges in an APG determines bounds on the computational scaling as a function of the total numbers of electrons, orbitals, and spin multiplicities. The edge counts extend a suite of Shavitt graph statistics based on these functional parameters. The derivation and the presentation of the formulas for the edge counts has been assisted by the bra–ket interchange symmetry and the particle-hole interchange symmetry in the GUGA formalism. These symmetry operators produce one-to-one correspondences between various sets of edges, and this yields identities among some edge count formulas. There are 208 possible edge types. Of these, some do not contribute to two-electron operators, some are related by bra–ket interchange symmetry, and some are related by particle-hole interchange symmetry. For the remaining unique edge types, explicit expressions are derived for the numbers of edges.

Quantum Fisher information and its super additivity in an anisotropic quantum Rabi model

In this paper, we study the additivity of quantum Fisher information (QFI) in a coupled system composed by a two-level system and a bosonic mode, which is described by an anisotropic Rabi model. Utilizing a unitary transformation approach, we obtain the approximate ground state for the global state and the reduced density matrix for each subsystem. We find the additivity of QFI, that is, the summation of QFI for two subsystems is always larger than that of the global system. We hope our work will stimulate the studies of quantum metrology in hybrid system.

Beyond Rational Systems: Managing Organizational Conflicts From Pluralistic, Open Systems and Stakeholder Perspectives

This paper examines organizational conflict in the context of rationalist, pluralist, open systems and stakeholder approaches. It argues that the prevailing rational and unitary approaches which dominate organizational analysis are inadequate theoretical tools for understanding the dynamics of organizational conflicts in a pluralistic society. Methodologically, the research approach is built on meta-synthesis. A meta-synthesis is a research approach that brings together qualitative data to form a new interpretation of a research field. From this approach, the paper critically examines three of the dominant approaches in organizational theorizing (the rational, pluralist and open systems perspectives) and their implications for understanding and managing organizational conflict. A synthesis of the literature combines the three perspectives to propose a framework for managing conflicts in organizations. The paper suggests that the open system perspective, in line with a pluralist perspective, is an appropriate framework for studying the relationship between stakeholder management and conflict management and for understanding the dynamics and the forces shaping conflicts in organizations. A stakeholder approach for understanding interests and sources of organizational conflicts is presented including stakeholders’ sources of power and legitimacy. Finally, a framework encompassing strategies for managing organizational conflicts by applying principles of stakeholder management are suggested.

New implementation of spin‐orbit coupling calculation on multi‐configuration electron correlation theory

AbstractFor treating both relativistic effect and electron correlation, the spin‐free exact two‐component and spin‐dependent first‐order Douglas–Kroll–Hess Hamiltonian and the state‐interaction (SI) method are combined to calculate the spin‐orbit coupling (SOC) on multi‐configuration electron correlation theory. In this method, SOC is evaluated via SI over electronic states from the complete active space self‐consistent field calculation, and dynamic correlation can be reckoned with the high‐level multi‐reference electron correlation theory. Work equations to calculate SOC matrix elements over Gelfand states in the framework of the graphic unitary group approach are presented. Benchmark calculations have verified the validity of the implementation. As a pilot application, the internally contracted multi‐reference configuration interaction with the inclusion of SOC via the SI approach produces reasonable equilibrium bond length and harmonic vibrational frequency of the ground state of AuO, as well as the transition energy of .

An Analysis of the Determinants of Household Expenditures in Rwanda

Economists use two different approaches, unitary and collective, to analyze household decisions. The unitary approach ignores the differences between single-person and multi-person households, whereas the collective approach states that each person in the household must be characterized by specific preferences. The household’s decisions concern mainly the allocation of their income to current consumption or for savings and future consumer expenditures. This study uses the Comprehensive Food Security and Vulnerability Analysis (CFSVA) data collected from a random sample in 2015 in Rwanda. The ordinary least squares (OLS) method was applied to a linear regression model to estimate the household demand functions (total household consumption expenditures, household food consumption expenditures and household nonfood consumption expenditures). The results show that the socioeconomic characteristics of the household, the possession of productive assets and wealth conditions as well as the household locational controls are among the primary drivers of its consumption expenditures. The findings highlight the policy efforts that improve household human capital (education, health), access to and capitalization of productive assets and financial capital, continuous urbanization of rural areas, and sustained provision of quality infrastructure, to achieve high standards of household welfare.