137 research outputs found
A jackknife approach to quantifying single-trial correlation between covariance-based metrics undefined on a single-trial basis
A DCM study of spectral asymmetries in feedforward and feedback connections between visual areas V1 and V4 in the monkey
Brain rhythms define distinct interaction networks with differential dependence on anatomy
Cognitive functions are subserved by rhythmic neuronal synchronization across widely distributed brain areas. In 105 area pairs, we investigated functional connectivity (FC) through coherence, power correlation, and Granger causality (GC) in the theta, beta, high-beta, and gamma rhythms. Between rhythms, spatial FC patterns were largely independent. Thus, the rhythms defined distinct interaction networks. Importantly, networks of coherence and GC were not explained by the spatial distributions of the strengths of the rhythms. Those networks, particularly the GC networks, contained clear modules, with typically one dominant rhythm per module. To understand how this distinctiveness and modularity arises on a common anatomical backbone, we correlated, across 91 area pairs, the metrics of functional interaction with those of anatomical projection strength. Anatomy was primarily related to coherence and GC, with the largest effect sizes for GC. The correlation differed markedly between rhythms, being less pronounced for the beta and strongest for the gamma rhythm
Counting valence quarks at RHIC and LHC
We consider the Nuclear Modification Ratios in heavy ion collisions, R_CP and
R_AA, in the region of intermediate transverse momentum, and study the
dependency upon the constituent quark composition of the observed hadron.
Adopting a two component recombination/fragmentation model, validated by
experimental information from STAR and PHENIX, we show that a clear distinction
is predicted for the f0(980) between the assumptions of or
diquark-antidiquark content.Comment: 14 pages, 11 eps figures, added figures and minor corrections, to
appear in Phys. Lett.
Jet hadrochemistry as a characteristics of jet quenching
Jets produced in nucleus-nucleus collisions at the LHC are expected to be
strongly modified due to the interaction of the parton shower with the dense
QCD matter. Here, we point out that jet quenching can leave signatures not only
in the longitudinal and transverse jet energy and multiplicity distributions,
but also in the hadrochemical composition of the jet fragments. In particular,
we show that even in the absence of medium effects at or after hadronization,
the medium-modification of the parton shower can result in significant changes
in jet hadrochemistry. We discuss how jet hadrochemistry can be studied within
the high-multiplicity environment of nucleus-nucleus collisions at the LHC.Comment: 15 pages, 7 figures, LaTe
Calculating Quenching Weights
We calculate the probability (``quenching weight'') that a hard parton
radiates an additional energy fraction due to scattering in spatially extended
QCD matter. This study is based on an exact treatment of finite in-medium path
length, it includes the case of a dynamically expanding medium, and it extends
to the angular dependence of the medium-induced gluon radiation pattern. All
calculations are done in the multiple soft scattering approximation
(Baier-Dokshitzer-Mueller-Peign\'e-Schiff--Zakharov ``BDMPS-Z''-formalism) and
in the single hard scattering approximation (N=1 opacity approximation). By
comparison, we establish a simple relation between transport coefficient, Debye
screening mass and opacity, for which both approximations lead to comparable
results. Together with this paper, a CPU-inexpensive numerical subroutine for
calculating quenching weights is provided electronically. To illustrate its
applications, we discuss the suppression of hadronic transverse momentum
spectra in nucleus-nucleus collisions. Remarkably, the kinematic constraint
resulting from finite in-medium path length reduces significantly the
transverse momentum dependence of the nuclear modification factor, thus leading
to consistency with the data measured at the Relativistic Heavy Ion Collider
(RHIC).Comment: 45 pages LaTeX, 20 eps-figure
Recent high-pt results from STAR
We present selected recent results of multi-hadron correlation measurements
in azimuth and pseudorapidity at intermediate and high \pt{} in Au+Au
collisions at GeV, from the STAR experiment at RHIC. At
intermediate \pt, measurements are presented that attempt to determine the
origin of the associated near-side (small \dphi) yield at large pseudo-rapidity
difference \deta{} that is found to be present in heavy ion collisions. In
addition, results are reported on new multi-hadron correlation measures at
high-\pt{} that use di-hadron triggers and multi-hadron cluster triggers with
the goal to constrain the underlying jet kinematics better than in the existing
measurements of inclusive spectra and di-hadron correlations.Comment: 6 pages, 8 figures. Prepared for 3rd International Conference on Hard
and Electro- Magnetic Probes of High-Energy Nuclear Collisions (Hard Probes
2008), submitted to EPJ
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