552 research outputs found
Functional brain networks involved in gaze and emotional processing
Eye-gaze direction plays a fundamental role in the perception of facial features and particularly the processing of emotional facial expressions. Yet, the neural underpinnings of the integration of eye gaze and emotional facial cues are not well understood. The primary aim of this study was to delineate the functional networks that subserve the recognition of emotional expressions as a function of eye gaze. Participants were asked to identify happy, angry, or neutral faces, displayed with direct or averted gaze, while their neural responses were measured with fMRI. The results showed that recognition of happy expressions, irrespective of eye-gaze direction, engaged the critical nodes of the default mode network. Recognition of angry faces, on the other hand, was gaze-dependent, engaging the critical nodes of the salience network when presented with direct gaze, but fronto-parietal areas when presented with averted gaze. Functional connectivity analysis further showed gaze-dependent engagement of a large-scale network connected to bilateral amygdala during the recognition of angry expressions. This study provides important insights into the functional connectivity between the amygdala and other critical social-cognitive brain nodes, which are essential in processing of ambiguous, potentially threatening social signals. These findings have implications for psychiatric disorders, such as post-traumatic stress disorder, which are characterized by aberrant limbic connectivity
Suppressed supersymmetry breaking terms in the Higgs sector
We study the little hierarchy between mass parameters in the Higgs sector and
other SUSY breaking masses. This type of spectrum can relieve the fine-tuning
problem in the MSSM Higgs sector. Our scenario can be realized by
superconformal dynamics. The spectrum in our scenario has significant
implications in other phenomenological aspects like the relic abundance of the
lightest neutralino and relaxation of the unbounded-from-below constraints.Comment: 14 pages, late
Z decays into light gluinos: a calculation based on unitarity
The Z boson can decay to a pair of light gluinos through loop-mediated
processes. Based on unitarity of the S-matrix, the imaginary part of the decay
amplitude is computed in the presence of a light bottom squark. This imaginary
part can provide useful information on the full amplitude. Implications are
discussed for a recently proposed light gluino and light bottom squark
scenario.Comment: 19 pages, LaTeX, 3 figures, submitted to Phys. Rev.
Cold event in the South Atlantic Bight during summer of 2003: Model simulations and implications
A set of model simulations are used to determine the principal forcing mechanisms that resulted in anomalously cold water in the South Atlantic Bight (SAB) in the summer of 2003. Updated mass field and elevation boundary conditions from basin-scale Hybrid Coordinate Ocean Model (HYCOM) simulations are compared to climatological forcing to provide offshore and upstream influences in a one-way nesting sense. Model skill is evaluated by comparing model results with observations of velocity, water level, and surface and bottom temperature. Inclusion of realistic atmospheric forcing, river discharge, and improved model dynamics produced good skill on the inner shelf and midshelf. The intrusion of cold water onto the shelf occurred predominantly along the shelf-break associated with onshore flow in the southern part of the domain north of Cape Canaveral (29° to 31.5°). The atmospheric forcing (anomalously strong and persistent upwelling-favorable winds) was the principal mechanism driving the cold event. Elevated river discharge increased the level of stratification across the inner shelf and midshelf and contributed to additional input of cold water into the shelf. The resulting pool of anomalously cold water constituted more than 50% of the water on the shelf in late July and early August. The excess nutrient flux onto the shelf associated with the upwelling was approximated using published nitrate-temperature proxies, suggesting increased primary production during the summer over most of the SAB shelf
Gluino Pair Production at Linear e^+e^- Colliders
We study the potential of high-energy linear colliders for the
production of gluino pairs within the Minimal Supersymmetric Standard Model
(MSSM). In this model, the process is mediated by
quark/squark loops, dominantly of the third generation, where the mixing of
left- and right-handed states can become large. Taking into account realistic
beam polarization effects, photon and -boson exchange, and current mass
exclusion limits, we scan the MSSM parameter space for various
center-of-mass energies to determine the regions, where gluino production
should be visible.Comment: 22 pages, 9 figure
Constraints on Baryon-Nonconserving Yukawa Couplings in a Supersymmetric Theory
The 1-loop evolution of couplings in the minimal supersymmetric standard
model, extended to include baryon nonconserving operators through
explicit -parity violation, is considered keeping only
superpotential terms involving the maximum possible number of third generation
superfields. If all retained Yukawa couplings are required to remain in
the perturbative domain upto the scale of gauge group unification,
upper bounds ensue on the magnitudes of the coupling strengths at
the supersymmetry breaking scale, independent of the model of unification. They
turn out to be similar to the corresponding fixed point values reached from a
wide range of (including all greater than unity) at the unification
scale. The coupled evolution of the top and Yukawa couplings results
in a reduction of the fixed point value of the former.Comment: PRL-TH-94/8 and TIFR/TH/94-7, 15 pages, LaTe
A Detailed Study of the Gluino Decay into the Third Generation Squarks at the CERN LHC
In supersymmetric models a gluino can decay into tb\tilde{\chi}^{\pm}_1
through a stop or a sbottom. The decay chain produces an edge structure in the
m_{tb} distribution. Monte Carlo simulation studies show that the end point and
the edge height would be measured at the CERN LHC by using a sideband
subtraction technique. The stop and sbottom masses as well as their decay
branching ratios are constrained by the measurement. We study interpretations
of the measurement in the minimal supergravity model. We also study the gluino
decay into tb and \tilde{\chi}^{\pm}_2 as well as the influence of the stop
left-right mixing on the m_{bb} distribution of the tagged events.Comment: revtex, 20 pages in PRD format, 35 eps file
Bessel Process and Conformal Quantum Mechanics
Different aspects of the connection between the Bessel process and the
conformal quantum mechanics (CQM) are discussed. The meaning of the possible
generalizations of both models is investigated with respect to the other model,
including self adjoint extension of the CQM. Some other generalizations such as
the Bessel process in the wide sense and radial Ornstein- Uhlenbeck process are
discussed with respect to the underlying conformal group structure.Comment: 28 Page
Supersymmetric effects in top quark decay into polarized W-boson
We investigate the one-loop supersymmetric QCD (SUSY-QCD) and electroweak
(SUSY-EW) corrections to the top quark decay into a b-quark and a longitudinal
or transverse W-boson. The corrections are presented in terms of the
longitudinal ratio \Gamma(t-->W_L b)/\Gamma(t--> W b) and the transverse ratio
\Gamma(t-->W_- b)/\Gamma(t--> W b). In most of the parameter space, both
SUSY-QCD and SUSY-EW corrections to these ratios are found to be less than 1%
in magnitude and they tend to have opposite signs. The corrections to the total
width \Gamma(t-->W b) are also presented for comparison with the existing
results in the literature. We find that our SUSY-EW corrections to the total
width differ significantly from previous studies: the previous studies give a
large correction of more than 10% in magnitude for a large part of the
parameter space while our results reach only few percent at most.Comment: Version in PRD (explanation and refs added
Crossover from two- to three-dimensional critical behavior for nearly antiferromagnetic itinerant electrons
The crossover from two- to three-dimensional critical behavior of nearly
antiferromagnetic itinerant electrons is studied in a regime where the
inter-plane single-particle motion of electrons is quantum-mechanically
incoherent because of thermal fluctuations. This is a relevant regime for very
anisotropic materials like the cuprates. The problem is studied within the
Two-Particle Self-Consistent approach (TPSC), that has been previously shown to
give a quantitative description of Monte Carlo data for the Hubbard model. It
is shown that TPSC belongs to the limit of the universality class. However, contrary to the usual approaches,
cutoffs appear naturally in the microscopic TPSC theory so that parameter-free
calculations can be done for Hubbard models with arbitrary band structure. A
general discussion of universality in the renormalized-classical crossover from
to is also given.Comment: Revtex, 23 pages + 6 postcript figures (with epsfile
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