18,497 research outputs found

    Quantum-to-Classical Reduction of Quantum Master Equations

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    A general method of quantum-to-classical reduction of quantum dynamics is described. The key aspect of our method is the similarity transformation of the Liouvillian, which provides a new perspective. In conventional studies of quantum energy transport, the rotating wave approximation has been frequently regarded as an inappropriate approach because it causes the energy flow through the system to vanish. Our formulation elucidates as to why this unphysical result occurs and provides a solution for the problem. That is, not only the density matrix but also the physical quantity is to be transformed. Moreover, we show that quantum dynamics can be "exactly" replaced with classical equations for the calculation of the transport efficiency.Comment: 13 pages, 2 figures; To appear in Prog. Theor. Exp. Phy

    Endogenous Women's Autonomy and the Use of Reproductive Health Services: Empirical Evidence from Tajikistan

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    Though gender equity is widely considered to be a key to improving maternal health in developing countries, little empirical evidence has been presented to support this claim. This paper investigates whether or not and how female autonomy within the household affects women's use of reproductive health care in Tajikistan, where the situation of maternal health and gender equity is worse compared with neighbouring countries. Estimation is performed using bivariate probit models in which woman's use of health services and the level of female autonomy are recursively and simultaneously determined. Empirical results reveal that female autonomy measured by women's decision-making on child wellbeing and on economic affairs within the household increases the probability of receiving both antenatal and delivery care. Policymakers need to address women's empowerment in the household in addition to implementing direct health interventions towards improvement of maternal health.Female autonomy; Antenatal care; Delivery care; Reproductive health services; Tajikistan; Bivariate probit model

    Model-independent determination of the compositeness of near-threshold quasibound states

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    We study the compositeness of near-threshold states to clarify the internal structure of exotic hadron candidates. Within the framework of effective field theory, we extend the Weinberg's weak-binding relation to include the nearby CDD (Castillejo-Dalitz-Dyson) pole contribution with the help of the Pade approximant. Finally, using the extended relation, we conclude that the CDD pole contribution to the Lambda(1405) baryon in the Kbar N amplitude is negligible.Comment: 5 pages, Proceedings of the 14th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon (MENU2016), July 25-30, 2016, Kyoto, Japa

    Generalized weak-binding relations of compositeness in effective field theory

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    We study the compositeness of near-threshold states to investigate the internal structure of exotic hadron candidates. Within the framework of effective field theory, Weinberg's weak-binding relation is extended to more general cases by easing several preconditions. First, by evaluating the contribution from the decay channel, we obtain the generalized relation for unstable quasibound states. Next, we generalize the relation to include the nearby CDD (Castillejo-Dalitz-Dyson) pole contribution with the help of the Pade approximant. The validity of the estimation with the generalized weak-binding relations is examined by numerical calculations. The method to systematically evaluate the error in the weak-binding relation is presented. Finally, by applying the extended relation to Lambda(1405), f0(980) and a0(980), we discuss their internal structure, in comparison with other approaches.Comment: 46 pages, 12 figures, published versio
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