Berry phase theory of planar Hall effect in Topological Insulators

Negative longitudinal magnetoresistance, in the presence of an external magnetic field parallel to the direction of an applied current, has recently been experimentally verified in Weyl semimetals and topological insulators in the bulk conduction limit. The appearance of negative longitudinal magnetoresistance in topological semimetals is understood as an effect of chiral anomaly, whereas it is not well-defined in topological insulators. Another intriguing phenomenon, planar Hall effect - appearance of a transverse voltage in the plane of applied co-planar electric and magnetic fields not perfectly aligned to each other, a configuration in which the conventional Hall effect vanishes, has recently been suggested to exist in Weyl semimetals. In this paper we present a quasi-classical theory of planar Hall effect of a three-dimensional topological insulator in the bulk conduction limit. Starting from Boltzmann transport equations we derive the expressions for planar Hall conductivity and longitudinal magnetoconductivity in topological insulators and show the important roles played by the orbital magnetic moment for the appearance of planar Hall effect. Our theoretical results predict specific experimental signatures for topological insulators that can be directly checked in experiments.Comment: 18 pages, 3 figure

Post Covid-19 and business analytics

This paper highlights the way companies can apply artificial intelligence (AI) in the post Covid-19 period. We show that how the AI can be advantageous to develop an inclusive model and apply to the businesses of various sizes. The recommendation can be beneficial for academic researchers to identify several ways to overcome the obstacles that companies may face in post Covid-19 period. The paper also addresses few major global issues, which can assist the policy makers to consider developing a business model to bounce back the world economy after this crisis is over. Overall, this paper enhances the understanding of stakeholders of business about the importance of application of the AI in businesses in a volatile market in post Covid-19 period

Gender inequality and disabled inclusivity in accounting higher education and profession during financial crisis

In this paper, we find that during financial crises, the wage gap between female and male accounting professionals reduces and affects gender inequality in higher education. In addition, less support and lower wages for disabled accounting professionals demotivate disabled students in accounting higher education. Because of budget cuts during financial crisis, universities limit their support to women and the disabled. We consider 104 universities from the UK Higher Education Statistic Agency (HESA) database for 2005– 2011. The theoretical and empirical findings of this paper establish the positive growth in female students and the negative growth in disabled accounting students during the recent financial crisis. The established link between higher education and the accounting profession enriches the existing accounting literature and assists policymakers in identifying a better strategy to enhance equality and inclusion of disabled students in accounting higher education to address inequality and non-inclusivity in the accounting profession, especially during financial crisis

Mirror anomaly and anomalous Hall effect in type-I Dirac semimetals

In addition to the well known chiral anomaly, Dirac semimetals have been argued to exhibit mirror anomaly, close analogue to the parity anomaly of ($2+1$)-dimensional massive Dirac fermions. The observable response of such anomaly is manifested in a singular step-like anomalous Hall response across the mirror-symmetric plane in the presence of a magnetic field. Although this result seems to be valid in type-II Dirac semimetals (strictly speaking, in the linearized theory), we find that type-I Dirac semimetals do not possess such an anomaly in anomalous Hall response even at the level of the linearized theory. In particular, we show that the anomalous Hall response continuously approaches zero as one approaches the mirror symmetric angle in a type-I Dirac semimetal as opposed to the singular Hall response in a type-II Dirac semimetal. Moreover, we show that, under certain condition, the anomalous Hall response may vanish in a linearized type-I Dirac semimetal, even in the presence of time reversal symmetry breaking.Comment: 6 pages, 5 figure

Estimating the effect of joint interventions from observational data in sparse high-dimensional settings

We consider the estimation of joint causal effects from observational data. In particular, we propose new methods to estimate the effect of multiple simultaneous interventions (e.g., multiple gene knockouts), under the assumption that the observational data come from an unknown linear structural equation model with independent errors. We derive asymptotic variances of our estimators when the underlying causal structure is partly known, as well as high-dimensional consistency when the causal structure is fully unknown and the joint distribution is multivariate Gaussian. We also propose a generalization of our methodology to the class of nonparanormal distributions. We evaluate the estimators in simulation studies and also illustrate them on data from the DREAM4 challenge.Comment: 30 pages, 3 figures, 45 pages supplemen