Frustrated collisions and unconventional pairing on a quantum superlattice

We solve the problem of scattering and binding of two spin-1/2 fermions on a one-dimensional superlattice with a period of twice the lattice spacing analytically. We find the exact bound states and the scattering states, consisting of a generalized Bethe ansatz augmented with an extra scattering product due to "asymptotic" degeneracy. If a Bloch band is doubly occupied, the extra wave can be a bound state in the continuum corresponding to a single-particle interband transition. In all other cases, it corresponds to a quasi-momentum changing, frustrated collision.Comment: 4 pages, 2 figure

Facial behavior

: We provide an overview of the current state-of-the-art regarding research on facial behavior from what we hope is a well-balanced historical perspective. Based on a critical discussion of the main theoretical views of nonverbal facial activity (i.e., affect program theory, appraisal theory, dimensional theory, behavioral ecology), we focus on some key issues regarding the cohesion of emotion and expression, including the issue of “genuine smiles.” We argue that some of the challenges faced by the field are a consequence of these theoretical positions, their assumptions, and we discuss how they have generated and shaped research. A clear distinction of encoding and decoding processes may prove beneficial to identify specific problems – for example the use of posed expressions in facial expression research, or the impact of the psychological situation on the perceiver. We argue that knowledge of the functions of facial activity may be central to understanding what facial activity is truly about; this includes a serious consideration of social context at all stages of encoding and decoding. The chapter concludes with a brief overview of recent technical advances and challenges highlighted by the new field of “affective computing” concerned with facial activity

Salesforce control systems as direct antecedents of salesperson and sales unit performance: A literature review

[EN] The impact from sales control systems on individual and organizational effectiveness has been a major issue for scholars since these systems were conceptualized by Anderson and Oliver and Jaworski. Salesperson behavioral performance appears as an antecedent of outcome performance, and both are connected to sales unit effectiveness. This paper focuses on a deep literature review during the period 1983-2014, based on the control systems¿ typologies found, and summarizes the multiple evidences found, connecting this systems with the salesperson behavioral performance and the outcome performance ¿and between them-, and both individual results with the sales unit effectiveness, including its managerial implications. After the review of the 142 articles in the field, a cluster of four research directions are identified, namely: (1) the impact of the different variables and activities on the control systems and the performance levels, (2) the methodological variables, (3) the measures of the level control system or performance, and (4) the multisectorial, multicultural and multinational sales environment.Benet-Zepf, AT.; Marin-Garcia, JA.; Küster, I. (2017). Salesforce control systems as direct antecedents of salesperson and sales unit performance: A literature review. Business and Economics Journal. 8(1). doi:10.4172/2151-6219.1000281S2818

Quartz microstructures in nature and experiment — evidence of rapid plastic deformation and subsequent annealing

Quartz microstructures produced in short-term deformation and annealing experiments are compared with those in naturally deformed vein quartz in cores from the Long Valley Exploratory Well (Long Valley Caldera, California). The experiments are designed to simulate i) co-seismic deformation of quartz in the uppermost plastosphere and ii) annealing during post-seismic stress relaxation. The experiments are performed in a modified Griggs type solid medium apparatus. Natural polycrystalline quartz samples (grain size on the order of millimetres) are deformed at a temperature of 400°C, a confining pressure of 2GPa, and strain rates of ca. 10−4 s−1. The differential stress reaches 2–4GPa and the irreversible axial shortening is typically a few percent. In some experiments the samples have subsequently been annealed for ca. 14–15 h at elevated temperatures of 800–1000°C and low stresses (quasi-hydrostatic or nonhydrostatic conditions)...conferenc

Correlating Josephson supercurrents and Shiba states in quantum spins unconventionally coupled to superconductors

Local spins coupled to superconductors give rise to several emerging phenomena directly linked to the competition between Cooper pair formation and magnetic exchange. These effects are generally scrutinized using a spectroscopic approach which relies on detecting the in-gap bound modes arising from Cooper pair breaking, the so-called Yu-Shiba-Rusinov (YSR) states. However, the impact of local magnetic impurities on the superconducting order parameter remains largely unexplored. Here, we use scanning Josephson spectroscopy to directly visualize the effect of magnetic perturbations on Cooper pair tunneling between superconducting electrodes at the atomic scale. By increasing the magnetic impurity orbital occupation by adding one electron at a time, we reveal the existence of a direct correlation between Josephson supercurrent suppression and YSR states. Moreover, in the metallic regime, we detect zero bias anomalies which break the existing framework based on competing Kondo and Cooper pair singlet formation mechanisms. Based on first-principle calculations, these results are rationalized in terms of unconventional spin-excitations induced by the finite magnetic anisotropy energy. Our findings have far reaching implications for phenomena that rely on the interplay between quantum spins and superconductivity. The impact of local magnetic impurities on superconducting order parameter remains largely unexplored. Here, the authors visualize the effect of different magnetic perturbations on a superconductor, unveiling a rich correlation of the interplay between quantum spins and superconductivity in different spectroscopic regimes

Recursive Graphical Construction of Feynman Diagrams in phi^4 Theory: Asymmetric Case and Effective Energy

The free energy of a multi-component scalar field theory is considered as a functional W[G,J] of the free correlation function G and an external current J. It obeys non-linear functional differential equations which are turned into recursion relations for the connected Greens functions in a loop expansion. These relations amount to a simple proof that W[G,J] generates only connected graphs and can be used to find all such graphs with their combinatoric weights. A Legendre transformation with respect to the external current converts the functional differential equations for the free energy into those for the effective energy Gamma[G,Phi], which is considered as a functional of the free correlation function G and the field expectation Phi. These equations are turned into recursion relations for the one-particle irreducible Greens functions. These relations amount to a simple proof that Gamma[G,J] generates only one-particle irreducible graphs and can be used to find all such graphs with their combinatoric weights. The techniques used also allow for a systematic investigation into resummations of classes of graphs. Examples are given for resumming one-loop and multi-loop tadpoles, both through all orders of perturbation theory. Since the functional differential equations derived are non-perturbative, they constitute also a convenient starting point for other expansions than those in numbers of loops or powers of coupling constants. We work with general interactions through four powers in the field.Comment: 34 pages; abstract expanded; section IV.E about absorption of tadpoles and one related reference added; eqs. (20) and (23) corrected; further references added; some minor beautifications; to be published by Phys.Rev.