576 research outputs found
Body Use and Reference Group Impact: With Whom Do We Compare Our Bodies?
Fifty U.S. Olympic speedskating team members, 50 professional models, and 80 college students completed the Body Esteem Scale (BES: Franzoi & Shields, 1984) and indicated for each of the 35 BES items whether when evaluating themselves they most frequently use as a comparison standard same-sex people in general, same-sex professional models, or elite same-sex athletes. Consistent with social comparison theory that people seek similar others as comparison targets, college students were more likely than Olympic athletes or professional models to compare themselves to people in the general population, athletes were more likely than students or models to compare themselves to elite athletes, and models tended to be more likely than students or athletes to compare themselves to elite models. As hypothesized, college women more frequently than college men compared themselves to professional models when evaluating body aspects associated with weight concern and sexual attractiveness, and the more female skatersâ compared themselves to models, the more their negative body attitudes associated with weight concern increased and the more interested they were in changing weight-related body aspects
Relativistic ionization-rescattering with tailored laser pulses
The interaction of relativistically strong tailored laser pulses with an
atomic system is considered. Due to a special tailoring of the laser pulse, the
suppression of the relativistic drift of the ionized electron and a dramatic
enhancement of the rescattering probability is shown to be achievable. The high
harmonic generation rate in the relativistic regime is calculated and shown to
be increased by several orders of magnitude compared to the case of
conventional laser pulses. The energies of the revisiting electron at the
atomic core can approach the MeV domain, thus rendering hard x-ray harmonics
and nuclear reactions with single atoms feasible
Exact Asymptotic Behaviour of Fermion Correlation Functions in the Massive Thirring Model
We obtain an exact asymptotic expression for the two-point fermion
correlation functions in the massive Thirring model (MTM) and show that, for
, they reproduce the exactly known corresponding functions of the
massless theory, explicitly confirming the irrelevance of the mass term at this
point. This result is obtained by using the Coulomb gas representation of the
fermionic MTM correlators in the bipolar coordinate system.Comment: To appear in J. Phys. A: Math. Gen. 12 page
Quantum Electrodynamics in Two-Dimensions at Finite Temperature. Thermofield Bosonization Approach
The Schwinger model at finite temperature is analyzed using the Thermofield
Dynamics formalism. The operator solution due to Lowenstein and Swieca is
generalized to the case of finite temperature within the thermofield
bosonization approach. The general properties of the statistical-mechanical
ensemble averages of observables in the Hilbert subspace of gauge invariant
thermal states are discussed. The bare charge and chirality of the Fermi
thermofields are screened, giving rise to an infinite number of mutually
orthogonal thermal ground states. One consequence of the bare charge and
chirality selection rule at finite temperature is that there are innumerably
many thermal vacuum states with the same total charge and chirality of the
doubled system. The fermion charge and chirality selection rules at finite
temperature turn out to imply the existence of a family of thermal theta vacua
states parametrized with the same number of parameters as in zero temperature
case. We compute the thermal theta-vacuum expectation value of the mass
operator and show that the analytic expression of the chiral condensate for any
temperature is easily obtained within this approach, as well as, the
corresponding high-temperature behavior
1D generalized statistics gas: A gauge theory approach
A field theory with generalized statistics in one space dimension is
introduced. The statistics enters the scene through the coupling of the matter
fields to a statistical gauge field, as it happens in the Chern-Simons theory
in two dimensions. We study the particle-hole excitations and show that the
long wave length physics of this model describes a gas obeying the Haldane
generalized exclusion statistics. The statistical interaction is found to
provide a way to describe the low-T critical properties of one-dimensional
non-Fermi liquids.Comment: 8 pages, revte
On renormalizability of the massless Thirring model
We discuss the renormalizability of the massless Thirring model in terms of
the causal fermion Green functions and correlation functions of left-right
fermion densities. We obtain the most general expressions for the causal
two-point Green function and correlation function of left-right fermion
densities with dynamical dimensions of fermion fields, parameterised by two
parameters. The region of variation of these parameters is constrained by the
positive definiteness of the norms of the wave functions of the states related
to components of the fermion vector current. We show that the dynamical
dimensions of fermion fields calculated for causal Green functions and
correlation functions of left-right fermion densities can be made equal. This
implies the renormalizability of the massless Thirring model in the sense that
the ultra-violet cut-off dependence, appearing in the causal fermion Green
functions and correlation functions of left-right fermion densities, can be
removed by renormalization of the wave function of the massless Thirring
fermion fields only.Comment: 17 pages, Latex, the contribution of fermions with opposite chirality
is added,the parameterisation of fermion determinant by two parameters is
confirmed,it is shown that dynamical dimensions of fermion fields calculated
from different correlation functions can be made equal.This allows to remove
the dependence on the ultra-violet cut-off by the renormalization of the wave
function of Thirring fermion fields onl
Non-minimal couplings in two dimensional gravity: a quantum investigation
We investigate the quantum effects of the non-minimal matter-gravity
couplings derived by Cangemi and Jackiw in the realm of a specific fermionic
theory, namely the abelian Thirring model on a Riemann surface of genus zero
and one. The structure and the strength of the new interactions are seen to be
highly constrained, when the topology of the underlying manifold is taken into
account. As a matter of fact, by requiring to have a well-defined action, we
are led both to quantization rules for the coupling constants and to selection
rules for the correlation functions. Explicit quantum computations are carried
out in genus one (torus). In particular the two-point function and the chiral
condensate are carefully derived for this case. Finally the effective
gravitational action, coming from integrating out the fermionic degrees of
freedoom, is presented. It is different from the standard Liouville one: a new
non-local functional of the conformal factor arises and the central charge is
improved, depending also on the Thirring coupling constant. This last feature
opens the possibility of giving a new explicit representation of the minimal
series in terms of a fermionic interacting model.Comment: Latex, 41 Page
String-localized Quantum Fields and Modular Localization
We study free, covariant, quantum (Bose) fields that are associated with
irreducible representations of the Poincar\'e group and localized in
semi-infinite strings extending to spacelike infinity. Among these are fields
that generate the irreducible representations of mass zero and infinite spin
that are known to be incompatible with point-like localized fields. For the
massive representation and the massless representations of finite helicity, all
string-localized free fields can be written as an integral, along the string,
of point-localized tensor or spinor fields. As a special case we discuss the
string-localized vector fields associated with the point-like electromagnetic
field and their relation to the axial gauge condition in the usual setting.Comment: minor correction
Concept and benchmark results for Big Data energy forecasting based on Apache Spark
The present article describes a concept for the creation and application of energy forecasting models in a distributed environment. Additionally, a benchmark comparing the time required for the training and application of data-driven forecasting models on a single computer and a computing cluster is presented. This comparison is based on a simulated dataset and both R and Apache Spark are used. Furthermore, the obtained results show certain points in which the utilization of distributed computing based on Spark may be advantageous
Strong field approximation within a Faddeev-like formalism for laser-matter interactions
We consider the interaction of atomic hydrogen with an intense laser field
within the strong-field approximation. By using a Faddeev-like formalism, we
introduce a new perturbative series in the binding potential of the atom. As a
first test of this new approach, we calculate the electron energy spectrum in
the very simple case of a photon energy higher than the ionisation potential.
We show that by contrast to the standard perturbative series in the binding
potential obtained within the strong field approximation, the first terms of
the new series converge rapidly towards the results we get by solving the
corresponding time-dependent Schroedinger equation.Comment: 7 pages, 1 figur
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