5,235 research outputs found
Abelian monopoles and center vortices in Yang-Mills plasma
Condensation of the Abelian monopoles and the center vortices leads to
confinement of color in low temperature phase of Yang-Mills theory. We stress
that these topological magnetic degrees of freedom are also very important in
the deconfinement regime: at the point of the deconfinement phase transition
both the monopoles and the vortices are released into the thermal vacuum
contributing, in particular, to the equation of state and, definitely, to
transport properties of the hot gluonic medium. Thus, we argue that a novel,
magnetic component plays a crucial role. On the other hand, it was demonstrated
that an effective three-dimensional description can be brought, beginning with
high temperatures, down to the critical temperature by postulating existence of
a system of 3d Higgs fields. We propose to identify the 3d color-singlet Higgs
field with the 3d projection of the 4d magnetic vortices. Such identification
fits well the 3d properties of the theory and contributes to interpretation of
the magnetic component of the Yang-Mills plasma.Comment: 5 pages, 3 figures; talk at Quark Confinement and the Hadron
Spectrum, September 1-6 2008, Mainz, German
Dogs catch human yawns
This study is the first to demonstrate that human yawns are possibly contagious to domestic dogs (Canis familiaris). Twenty-nine dogs observed a human yawning or making control mouth movements. Twenty-one dogs yawned when they observed a human yawning, but control mouth movements did not elicit yawning from any of them. The presence of contagious yawning in dogs suggests that this phenomenon is not specific to primate species and may indicate that dogs possess the capacity for a rudimentary form of empathy. Since yawning is known to modulate the levels of arousal, yawn contagion may help coordinate dogâhuman interaction and communication. Understanding the mechanism as well as the function of contagious yawning between humans and dogs requires more detailed investigation
Cosmological test of gravity with polarizations of stochastic gravitational waves around 0.1-1 Hz
In general relativity, a gravitational wave has two polarization modes
(tensor mode), but it could have additional polarizations (scalar and vector
modes) in the early stage of the universe, where the general relativity may not
strictly hold and/or the effect of higher-dimensional gravity may become
significant. In this paper, we discuss how to detect extra-polarization modes
of stochastic gravitational wave background (GWB), and study the separability
of each polarization using future space-based detectors such as BBO and DECIGO.
We specifically consider two plausible setups of the spacecraft constellations
consisting of two and four clusters, and estimate the sensitivity to each
polarization mode of GWBs. We find that a separate detection of each
polarization mode is rather sensitive to the geometric configuration and
distance between clusters and that the clusters should be, in general,
separated by an appropriate distance. This seriously degrades the signal
sensitivity, however, for suitable conditions, space-based detector can
separately detect scalar, vector and tensor modes of GWBs with energy density
as low as ~10^-15.Comment: 16 pages, 11 figure
Do 18-month-olds really attribute mental states to others? A critical test
In the research reported here, we investigated whether 18-month-olds would use their own past experience of visual access to attribute perception and consequent beliefs to other people. Infants in this study wore either opaque blindfolds (opaque condition) or trick blindfolds that looked opaque but were actually transparent (trick condition). Then both groups of infants observed an actor wearing one of the same blindfolds that they themselves had experienced, while a puppet removed an object from its location. Anticipatory eye movements revealed that infants who had experienced opaque blindfolds expected the actor to behave in accordance with a false belief about the object's location, but that infants who had experienced trick blindfolds did not exhibit that expectation. Our results suggest that 18-month-olds used self-experience with the blindfolds to assess the actor's visual access and to update her belief state accordingly. These data constitute compelling evidence that 18-month-olds infer perceptual access and appreciate its causal role in altering the epistemic states of other people
Correlation of Local Order with Particle Mobility in Supercooled Liquids is Highly System Dependent
We investigate the connection between local structure and dynamical
heterogeneity in supercooled liquids. Through the study of four different
models we show that the correlation between a particle's mobility and the
degree of local order in nearby regions is highly system dependent. Our results
suggest that the correlation between local structure and dynamics is weak or
absent in systems that conform well to the mean-field picture of glassy
dynamics and strong in those that deviate from this paradigm. Finally, we
investigate the role of order-agnostic point-to-set correlations and reveal
that they provide similar information content to local structure measures, at
least in the system where local order is most pronounced.Comment: 6 pages, 3 figures and 6 page sup. with 5 figures and 1 tabl
INFORMATION CRITERIA FOR IMPULSE RESPONSE FUNCTION MATCHING ESTIMATION OF DSGE MODELS
We propose new information criteria for impulse response function matching estimators (IRFMEs). These estimators yield sampling distributions of the structural parameters of dynamic sto- chastic general equilibrium (DSGE) models by minimizing the distance between sample and theoretical impulse responses. First, we propose an information criterion to select only the responses that produce consistent estimates of the true but unknown structural parameters: the Valid Impulse Response Selection Criterion (VIRSC). The criterion is especially useful for mis-speci?ed models. Second, we propose a criterion to select the impulse responses that are most informative about DSGE model parameters: the Relevant Im- pulse Response Selection Criterion (RIRSC). These criteria can be used in combination to select the subset of valid impulse response functions with minimal dimension that yields asymptotically e¹ cient estimators. The criteria are general enough to apply to impulse responses estimated by VARs, local projections, and simulation methods. We show that the use of our criteria signi?cantly a§ects estimates and inference about key parameters of two well-known new Keynesian DSGE models. Monte Carlo evidence indicates that the criteria yield gains in terms of ?nite sample bias as well as o§ering tests statistics whose behavior is better approximated by ?rst order asymptotic theory. Thus, our criteria improve on existing methods used to implement IRFMEs.Output Growth Forecasts, Inflation Forecasts, Model Selection, Structural Change, Forecast Evaluation, Real-time data. Evaluation
Gluon propagators and center vortices at finite temperature
We study influence of center vortices on infrared properties of gluons in the
deconfinement phase of quenched QCD. We observe a significant suppression of
the magnetic component of the gluon propagator in the low-momentum region after
the vortices are removed from the gluon configurations. The propagator of the
electric gluon stays almost unaffected by the vortex removal. Our results
demonstrate that the center vortices are responsible for important
nonperturbative properties of the magnetic component of the quark-gluon plasma.Comment: 7 pages, 8 figures, talk presented at 27th International Symposium on
Lattice Field Theory (Lattice 2009), Beijing, 26-31 Jul 200
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