8,288 research outputs found
Extracting CKM phase from and ,
We discuss some aspects of the search for CP asymmetry in the three body B
decays, revealed through the interference among neighbor resonances in the
Dalitz plot. We propose a competitive method to extract the CKM angle
combining Dalitz plot amplitude analysis of
and untagged , . The method also obtains the
ratio and phase difference between the {\it tree} and {\it penguin}
contributions from and decays and the
CP asymmetry between and . From Monte Carlo studies of 100K
events for the neutral mesons, we show the possibility of measuring .Comment: Revised enlarged version to appear at Phys Rev
Simulating 2+1d Lattice QED with dynamical matter using ultracold atoms
We suggest a method to simulate lattice compact Quantum Electrodynamics
(cQED) using ultracold atoms in optical lattices, which includes dynamical
Dirac fermions in 2+1 dimensions. This allows to test dynamical effects of
confinement as well as 2d flux loops deformations and breaking, and to observe
Wilson-loop area-law.Comment: Includes supplementary material. Added references, minor
modification
Superradiance-like Electron Transport through a Quantum Dot
We theoretically show that intriguing features of coherent many-body physics
can be observed in electron transport through a quantum dot (QD). We first
derive a master equation based framework for electron transport in the
Coulomb-blockade regime which includes hyperfine (HF) interaction with the
nuclear spin ensemble in the QD. This general tool is then used to study the
leakage current through a single QD in a transport setting. We find that, for
an initially polarized nuclear system, the proposed setup leads to a strong
current peak, in close analogy with superradiant emission of photons from
atomic ensembles. This effect could be observed with realistic experimental
parameters and would provide clear evidence of coherent HF dynamics of nuclear
spin ensembles in QDs.Comment: 21 pages, 10 figure
Quantum phase transitions in matrix product systems
We investigate quantum phase transitions (QPTs) in spin chain systems
characterized by local Hamiltonians with matrix product ground states. We show
how to theoretically engineer such QPT points between states with predetermined
properties. While some of the characteristics of these transitions are
familiar, like the appearance of singularities in the thermodynamic limit,
diverging correlation length, and vanishing energy gap, others differ from the
standard paradigm: In particular, the ground state energy remains analytic, and
the entanglement entropy of a half-chain stays finite. Examples demonstrate
that these kinds of transitions can occur at the triple point of `conventional'
QPTs.Comment: 5 pages, 1 figur
Numerical Simulation of III-V Solar Cells Using D-AMPS
Numerical simulation of devices plays a crucial role in their design, performance prediction, and comprehension of the fundamental phenomena ruling their operation. Here, we present results obtained using the code D-AMPS-1D, that was conveniently modified to consider the particularities of III-V solar cell devices. This work, that is a continuation of a previous paper regarding solar cells for space applications, is focused on solar cells structures than find application for terrestrial use under concentrated solar illumination. The devices were fabricated at the Solar Energy Institute of the Technical University of Madrid (UPM). The first simulations results on InGaP cells are presented. The influence of band offsets and band bending at the window-emitter interface on the quantum efficiency was studied. A remarkable match of the experimental quantum efficiency was obtained. Finally, numerical simulation of single junction n-p InGaP-Ge solar cells was performed
Coupled h-m fracture interaction using fem with zero-thickness interface elements
Intensive hydraulic fracturing is a procedure employed for low permeability reservoir stimulation. This technique consists of generating a sequence of regularly spaced parallel fractures (multi-stage fracturing). The generation of a fracture involves the modiïŹcation of the local stress state, and therefore, in the case of multi-stage fracturing, the propagation of a certain fracture can be aïŹected by the injection sequence, as it has been observed with microseismicity monitoring [1]. This paper describes a study of this technique by means of the Finite Element Method with zero-thickness interface elements for the geo-mechanical modelling of discontinuities [2]. The technique consists in inserting interface elements in between standard elements to allow jumps in the displacement solution ïŹelds. For the mechanical problem, their kinematic constitutive variables are relative displacements, and the corresponding static variables are stress tractions. The relationship between variables is controlled via a fracture-based constitutive law with elasto-plastic structure [3]. Concerning the hydraulic problem, the interface formulation includes both the longitudinal ïŹow (with a longitudinal conductivity parameter strongly dependent on the fracture aperture), as well as and the transversal ïŹow across the element [4]. Previous work by the authors focused on the validation of the method, the analysis a single fracture plane problem [5, 6]. In this case the method is extended to allow free propagation of fractures in any direction, by means of inserting interface elements between all continuum elements. The results presented in this paper analyse the eïŹect of material properties, in particular fracture characterization, in the propagation and the eïŹect of diïŹerent major to minor principal horizontal stress ratio, on the trajectory and interaction of the fractures
Weakly compact operators and the strong* topology for a Banach space
Peer reviewedPublisher PD
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