299,513 research outputs found

### Ab initio investigation of intermolecular interactions in solid benzene

A computational strategy for the evaluation of the crystal lattice constants
and cohesive energy of the weakly bound molecular solids is proposed. The
strategy is based on the high level ab initio coupled-cluster determination of
the pairwise additive contribution to the interaction energy. The
zero-point-energy correction and non-additive contributions to the interaction
energy are treated using density functional methods. The experimental crystal
lattice constants of the solid benzene are reproduced, and the value of 480
meV/molecule is calculated for its cohesive energy

### Optical control of electron spin coherence in CdTe/(Cd,Mg)Te quantum wells

Optical control of the spin coherence of quantum well electrons by short
laser pulses with circular or linear polarization is studied experimentally and
theoretically. For that purpose the coherent electron spin dynamics in a
n-doped CdTe/(Cd,Mg)Te quantum well structure was measured by time-resolved
pump-probe Kerr rotation, using resonant excitation of the negatively charged
exciton (trion) state. The amplitude and phase shifts of the electron spin beat
signal in an external magnetic field, that are induced by laser control pulses,
depend on the pump-control delay and polarization of the control relative to
the pump pulse. Additive and non-additive contributions to pump-induced signal
due to the control are isolated experimentally. These contributions can be well
described in the framework of a two-level model for the optical excitation of
the resident electron to the trion.Comment: 15 pages, 18 figure

### Conduction band spin splitting and negative magnetoresistance in ${\rm A}_3{\rm B}_5$ heterostructures

The quantum interference corrections to the conductivity are calculated for
an electron gas in asymmetric quantum wells in a magnetic field. The theory
takes into account two different types of the spin splitting of the conduction
band: the Dresselhaus terms, both linear and cubic in the wave vector, and the
Rashba term, linear in wave vector. It is shown that the contributions of these
terms into magnetoconductivity are not additive, as it was traditionally
assumed. While the contributions of all terms of the conduction band splitting
into the D'yakonov--Perel' spin relaxation rate are additive, in the
conductivity the two linear terms cancel each other, and, when they are equal,
in the absence of the cubic terms the conduction band spin splitting does not
show up in the magnetoconductivity at all. The theory agrees very well with
experimental results and enables one to determine experimentally parameters of
the spin-orbit splitting of the conduction band.Comment: 8 pages, RevTeX, 4 Postscript figure

### Quantum Electroweak Symmetry Breaking Through Loop Quadratic Contributions

Based on two postulations that (i) the Higgs boson has a large bare mass $m_H
\gg m_h \simeq 125$ GeV at the characteristic energy scale $M_c$ which defines
the standard model (SM) in the ultraviolet region, and (ii) quadratic
contributions of Feynman loop diagrams in quantum field theories are physically
meaningful, we show that the SM electroweak symmetry breaking is induced by the
quadratic contributions from loop effects. As the quadratic running of Higgs
mass parameter leads to an additive renormalization, which distinguishes from
the logarithmic running with a multiplicative renormalization, the symmetry
breaking occurs once the sliding energy scale $\mu$ moves from $M_c$ down to a
transition scale $\mu =\Lambda_{EW}$ at which the additive renormalized Higgs
mass parameter $m^2_H(M_c/\mu)$ gets to change the sign. With the input of
current experimental data, this symmetry breaking energy scale is found to be
$\Lambda_{EW}\simeq 760$ GeV, which provides another basic energy scale for the
SM besides $M_c$. Studying such a symmetry breaking mechanism could play an
important role in understanding both the hierarchy problem and naturalness
problem. It also provides a possible way to explore the experimental
implications of the quadratic contributions as $\Lambda_{EW}$ lies within the
probing reach of the LHC and the future Great Collider.Comment: 10 pages, 2 figures, published versio

### Income Inequality Games

The paper explores different applications of the Shapley value for either inequality or poverty measures. We first investigate the problem of source decomposition of inequality measures, the so-called additive income sources inequality games, baed on the Shapley Value, introduced by Chantreuil and Trannoy (1999) and Shorrocks (1999). We show that multiplicative income sources inequality games provide dual results compared with Chantreuil and Trannoy's ones. We also investigate the case of multiplicative poverty games for which indices are non additively decomposable in order to capture contributions of sub-indices, which are multiplicatively connected with, as in the Sen-Shorrocks-Thon poverty index. We finally show in the case of additive poverty indices that the Shapley value may be equivalent to traditional methods of decomposition such as subgroup consistency and additive decompositions.

### Spontaneous Isotropy Breaking: A Mechanism for CMB Multipole Alignments

We introduce a class of models in which statistical isotropy is broken
spontaneously in the CMB by a non-linear response to long-wavelength
fluctuations in a mediating field. These fluctuations appear as a gradient
locally and pick out a single preferred direction. The non-linear response
imprints this direction in a range of multipole moments. We consider two
manifestations of isotropy breaking: additive contributions and multiplicative
modulation of the intrinsic anisotropy. Since WMAP exhibits an alignment of
power deficits, an additive contribution is less likely to produce the observed
alignments than the usual isotropic fluctuations, a fact which we illustrate
with an explicit cosmological model of long-wavelength quintessence
fluctuations. This problem applies to other models involving foregrounds or
background anisotropy that seek to restore power to the CMB. Additive models
that account directly for the observed power exacerbate the low power of the
intrinsic fluctuations. Multiplicative models can overcome these difficulties.
We construct a proof of principle model that significantly improves the
likelihood and generates stronger alignments than WMAP in 30-45% of
realizations.Comment: 13 pages, 10 figure

### Income Inequality Games

The paper explores different applications of the Shapley value for either inequality or poverty measures. We first investigate the problem of source decomposition of inequality measures, the so-called additive income sources inequality games, baed on the Shapley Value, introduced by Chantreuil and Trannoy (1999) and Shorrocks (1999). We show that multiplicative income sources inequality games provide dual results compared with Chantreuil and Trannoy's ones. We also investigate the case of multiplicative poverty games for which indices are non additively decomposable in order to capture contributions of sub-indices, which are multiplicatively connected with, as in the Sen Shorrocks-Thon poverty index. We finally show in the case of additive poverty indices that the Shapley value may be equivalent to traditional methods of decomposition such as subgroup consistency and additive decompositions.Inequality, Poverty, Shapley, Source decomposition.

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