787 research outputs found
Nonlinear Realization and Weyl Scale Invariant p=2 Brane
The action of Weyl scale invariant p=2 brane which breaks the target super
Weyl scale symmetry in the N=1, D=4 superspace down to the lower dimensional
Weyl symmetry W(1,2) is derived by the approach of nonlinear realization. The
dual form action for the Weyl scale invariant supersymmetric D2 brane is also
constructed. The interactions of localized matter fields on the brane with the
Nambu-Goldstone fields associated with the breaking of the symmetries in the
superspace and one spatial translation directions are obtained through the
Cartan one-forms of the Coset structures. The covariant derivatives for the
localized matter fields are also obtained by introducing Weyl gauge field as
the compensating field corresponding to the local scale transformation on the
brane world volume.Comment: 20 page
Elliptic Flow, Initial Eccentricity and Elliptic Flow fluctuations in Heavy Ion Collisions at RHIC
We present measurements of elliptic flow and event-by-event fluctuations
established by the PHOBOS experiment. Elliptic flow scaled by participant
eccentricity is found to be similar for both systems when collisions with the
same number of participants or the same particle area density are compared. The
agreement of elliptic flow between Au+Au and Cu+Cu collisions provides evidence
that the matter is created in the initial stage of relativistic heavy ion
collisions with transverse granularity similar to that of the participant
nucleons. The event-by-event fluctuation results reveal that the initial
collision geometry is translated into the final state azimuthal particle
distribution, leading to an event-by-event proportionality between the observed
elliptic flow and initial eccentricity.Comment: To appear in the proceedings of the Lake Louise Winter Institute
2007. The proceedings of the institute will be published by World Scientifi
Towards a common origin of the elliptic flow, ridge and alignment
It is claimed that elliptic flow, ridge and alignment are effects of
azimuthal asymmetry, which have a common origin evolving with primary energy
and stemming from the general structure of field-theoretical matrix elements.
It interrelates a new ridge-phenomenon, recently found at the LHC and RHIC,
with known coplanarity feature observed in collider jet physics as well as in
cosmic ray studies.Comment: 4 pages, few typos fixed, reference added, version published in JETP
Letter
Hotter, Denser, Faster, Smaller...and Nearly-Perfect: What's the matter at RHIC?
The experimental and theoretical status of the ``near perfect fluid'' at RHIC
is discussed. While the hydrodynamic paradigm for understanding collisions at
RHIC is well-established, there remain many important open questions to address
in order to understand its relevance and scope. It is also a crucial issue to
understand how the early equilibration is achieved, requiring insight into the
active degrees of freedom at early times.Comment: 10 Pages, 13 Figures, submitted to the proceedings of the Second
Meeting of the APS Topical Group on Hadronic Physics, Nashville, TN, October
22-24, 200
Specific Heat of Ce(1-x)La(x)RhIn(5) in Zero and Applied Magnetic Field: A Very Rich Phase Diagram
Specific heat and magnetization results as a function of field on single- and
poly-crystalline samples of Ce(1-x)La(x)RhIn(5) show 1.) a specific heat gamma
of about 100 mJ/moleK^2 (in agreement with recent dHvA results of Alvers et
al.); 2.) upturns at low temperatures in C/T and chi that fit a power law
behavior ( Griffiths phase non-Fermi liquid behavior); 3.) a field induced
anomaly in C/T as well as M vs H behavior in good agreement with the recent
Griffiths phase theory of Castro Neto and Jones, where M~H at low field, M ~
H^lambda above a crossover field, C/T ~ T^(-1+lambda) at low field, and C/T ~
(H^(2+lambda/2)/T^(3-lambda/2))*exp(-mu(eff)H/T) above the same crossover field
as determined in the magnetization and where lambda is independently determined
from the temperature dependence of chi at low temperatures, chi ~ T^(-1+lambda)
and low fields.Comment: 13 pages, 9 figures, to be published in Physical Review
Wounded nucleon model with realistic nucleon-nucleon collision profile and observables in relativistic heavy-ion collisions
We investigate the influence of the nucleon-nucleon collision profile
(probability of interaction as a function of the nucleon-nucleon impact
parameter) in the wounded nucleon model and its extensions on several
observables measured in relativistic heavy-ion collisions. We find that the
participant eccentricity coefficient, , as well as the higher
harmonic coefficients, , are reduced by 10-20% for
mid-peripheral collisions when the realistic (Gaussian) profile is used, as
compared to the case with the commonly-used hard-sphere profile. Similarly, the
multiplicity fluctuations, treated as the function of the number of wounded
nucleons in one of the colliding nuclei, are reduced by 10-20%. This
demonstrates that the Glauber Monte Carlo codes should necessarily use the
realistic nucleon-nucleon collision profile in precision studies of these
observables. The Gaussian collision profile is built-in in {\tt GLISSANDO}.Comment: 8 pages, 7 figure
The Importance of Correlations and Fluctuations on the Initial Source Eccentricity in High-Energy Nucleus-Nucleus Collisions
In this paper, we investigate various ways of defining the initial source
eccentricity using the Monte Carlo Glauber (MCG) approach. In particular, we
examine the participant eccentricity, which quantifies the eccentricity of the
initial source shape by the major axes of the ellipse formed by the interaction
points of the participating nucleons. We show that reasonable variation of the
density parameters in the Glauber calculation, as well as variations in how
matter production is modeled, do not significantly modify the already
established behavior of the participant eccentricity as a function of collision
centrality. Focusing on event-by-event fluctuations and correlations of the
distributions of participating nucleons we demonstrate that, depending on the
achieved event-plane resolution, fluctuations in the elliptic flow magnitude
lead to most measurements being sensitive to the root-mean-square, rather
than the mean of the distribution. Neglecting correlations among
participants, we derive analytical expressions for the participant eccentricity
cumulants as a function of the number of participating nucleons,
\Npart,keeping non-negligible contributions up to \ordof{1/\Npart^3}. We
find that the derived expressions yield the same results as obtained from
mixed-event MCG calculations which remove the correlations stemming from the
nuclear collision process. Most importantly, we conclude from the comparison
with MCG calculations that the fourth order participant eccentricity cumulant
does not approach the spatial anisotropy obtained assuming a smooth nuclear
matter distribution. In particular, for the Cu+Cu system, these quantities
deviate from each other by almost a factor of two over a wide range in
centrality.Comment: 18 pages, 10 figures, submitted to PR
Deep-coverage whole genome sequences and blood lipids among 16,324 individuals.
Large-scale deep-coverage whole-genome sequencing (WGS) is now feasible and offers potential advantages for locus discovery. We perform WGS in 16,324 participants from four ancestries at mean depth >29X and analyze genotypes with four quantitative traits-plasma total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol, and triglycerides. Common variant association yields known loci except for few variants previously poorly imputed. Rare coding variant association yields known Mendelian dyslipidemia genes but rare non-coding variant association detects no signals. A high 2M-SNP LDL-C polygenic score (top 5th percentile) confers similar effect size to a monogenic mutation (~30 mg/dl higher for each); however, among those with severe hypercholesterolemia, 23% have a high polygenic score and only 2% carry a monogenic mutation. At these sample sizes and for these phenotypes, the incremental value of WGS for discovery is limited but WGS permits simultaneous assessment of monogenic and polygenic models to severe hypercholesterolemia
System size and centrality dependence of charged hadron transverse momentum spectra in Au+Au and Cu+Cu collisions at sqrt(s) = 62.4 and 200 GeV
We present transverse momentum distributions of charged hadrons produced in
Cu+Cu collisions at sqrt(s) = 62.4 and 200 GeV. The spectra are measured for
transverse momenta of 0.25 < p_T < 5.0 GeV/c at sqrt(s) = 62.4 GeV and 0.25 <
p_T < 7.0 GeV/c at sqrt(s) = 200 GeV, in a pseudo-rapidity range of 0.2 < eta <
1.4. The nuclear modification factor R_AA is calculated relative to p+p data at
both collision energies as a function of collision centrality. At a given
collision energy and fractional cross-section, R_AA is observed to be
systematically larger in Cu+Cu collisions compared to Au+Au. However, for the
same number of participating nucleons, R_AA is essentially the same in both
systems over the measured range of p_T, in spite of the significantly different
geometries of the Cu+Cu and Au+Au systems.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let
- …