63,407 research outputs found
Unintegrated parton distributions in nuclei
We study how unintegrated parton distributions in nuclei can be calculated
from the corresponding integrated partons using the EPS09 parametrization. The
role of nuclear effects is presented in terms of the ratio
for both large and small domains.Comment: 9 pages, 4 figure
Break-down of the density-of-states description of scanning tunneling spectroscopy in supported metal clusters
Low-temperature scanning tunneling spectroscopy allows to probe the
electronic properties of clusters at surfaces with unprecedented accuracy. By
means of quantum transport theory, using realistic tunneling tips, we obtain
conductance curves which considerably deviate from the cluster's density of
states. Our study explains the remarkably small number of peaks in the
conductance spectra observed in recent experiments. We demonstrate that the
unambiguous characterization of the states on the supported clusters can be
achieved with energy-resolved images, obtained from a theoretical analysis
which mimics the experimental imaging procedure.Comment: 5 pages, 3 figure
VIMOS-VLT spectroscopy of the giant Ly-alpha nebulae associated with three z~2.5 radio galaxies
The morphological and spectroscopic properties of the giant (>60 kpc)
Ly-alpha nebulae associated with three radio galaxies at z~2.5 (MRC 1558-003,
MRC 2025-218 and MRC 0140-257) have been investigated using integral field
spectroscopic data obtained with VIMOS on VLT.
The morphologies are varied. The nebula of one source has a centrally peaked,
rounded appearance. In the other two objects, it consists of two spatial
components. The three nebulae are aligned with the radio axis within <30 deg.
The total Ly-alpha luminosities are in the range (0.3-3.4) x 1e44 erg s-1. The
Ly-alpha spectral profile shows strong variation through the nebulae, with FWHM
values in the range ~400-1500 km s-1 and velocity shifts V~120-600 km s-1.
We present an infall model which can explain successfully most Ly-alpha
morphological and spectroscopic properties of the nebula associated with MRC
1558-003. This adds further support to our previous conclusion that the
_quiescent_ giant nebulae associated with this and other high redshift powerful
radio galaxies are in infall. A problem for this model is the difficulty to
reproduce the large Ly-alpha FWHM values.
We have discovered a giant (~85 kpc) Ly-alpha nebula associated with the
radio galaxy MRC 0140-257 at z=2.64. It shows strikingly relaxed kinematics
(FWHM2) radio galaxies.Comment: 14 pages, 13 figures. Accepted for publication in MNRA
Angiogenesis-dependent and independent phases of intimal hyperplasia.
BACKGROUND: Neointimal vascular smooth muscle cell (VSMC) proliferation is a primary cause of occlusive vascular disease, including atherosclerosis, restenosis after percutaneous interventions, and bypass graft stenosis. Angiogenesis is implicated in the progression of early atheromatous lesions in animal models, but its role in neointimal VSMC proliferation is undefined. Because percutaneous coronary interventions result in induction of periadventitial angiogenesis, we analyzed the role of this process in neointima formation. METHODS AND RESULTS: Local injury to the arterial wall in 2 different animal models induced periadventitial angiogenesis and neointima formation. Application of angiogenesis stimulators vascular endothelial growth factor (VEGF-A165) or a proline/arginine-rich peptide (PR39) to the adventitia of the injured artery induced a marked increase in neointimal thickening beyond that seen with injury alone in both in vivo models. Inhibition of either VEGF (with soluble VEGF receptor 1 [sFlt1]) or fibroblast growth factor (FGF) (with a dominant=negative form of FGF receptor 1 [FGF-R1DN]), respectively, signaling reduced adventitial thickening induced by VEGF and PR39 to the level seen with mechanical arterial injury alone. However, neither inhibitor was effective in preventing neointimal thickening after mechanical injury when administered in the absence of angiogenic growth factor. CONCLUSIONS: Our findings indicate that adventitial angiogenesis stimulates intimal thickening but does not initiate it
BB Potentials in Quenched Lattice QCD
The potentials between two B-mesons are computed in the heavy-quark limit
using quenched lattice QCD at . Non-zero central
potentials are clearly evident in all four spin-isospin channels, (I,s_l) =
(0,0) , (0,1) , (1,0) , (1,1), where s_l is the total spin of the light degrees
of freedom. At short distance, we find repulsion in the channels and
attraction in the I=s_l channels. Linear combinations of these potentials that
have well-defined spin and isospin in the t-channel are found, in three of the
four cases, to have substantially smaller uncertainties than the potentials
defined with the s-channel (I,s_l), and allow quenching artifacts from single
hairpin exchange to be isolated. The BB*\pi coupling extracted from the
long-distance behavior of the finite-volume t-channel potential is found to be
consistent with quenched calculations of the matrix element of the isovector
axial-current. The tensor potentials in both of the s_l = 1 channels are found
to be consistent with zero within calculational uncertainties.Comment: 30 page
Search for Heavy Neutral MSSM Higgs Bosons with CMS: Reach and Higgs-Mass Precision
The search for MSSM Higgs bosons will be an important goal at the LHC. We
analyze the search reach of the CMS experiment for the heavy neutral MSSM Higgs
bosons with an integrated luminosity of 30 or 60 fb^-1. This is done by
combining the latest results for the CMS experimental sensitivities based on
full simulation studies with state-of-the-art theoretical predictions of MSSM
Higgs-boson properties. The results are interpreted in MSSM benchmark scenarios
in terms of the parameters tan_beta and the Higgs-boson mass scale, M_A. We
study the dependence of the 5 sigma discovery contours in the M_A-tan_beta
plane on variations of the other supersymmetric parameters. The largest effects
arise from a change in the higgsino mass parameter mu, which enters both via
higher-order radiative corrections and via the kinematics of Higgs decays into
supersymmetric particles. While the variation of can shift the
prospective discovery reach (and correspondingly the ``LHC wedge'' region) by
about Delta tan_beta = 10, we find that the discovery reach is rather stable
with respect to the impact of other supersymmetric parameters. Within the
discovery region we analyze the accuracy with which the masses of the heavy
neutral Higgs bosons can be determined. We find that an accuracy of 1-4% should
be achievable, which could make it possible in favourable regions of the MSSM
parameter space to experimentally resolve the signals of the two heavy MSSM
Higgs bosons at the LHC.Comment: 24 pages, 8 figure
Egorov property in perturbed cat map
We study the time evolution of the quantum-classical correspondence (QCC) for
the well known model of quantised perturbed cat maps on the torus in the very
specific regime of semi-classically small perturbations. The quality of the QCC
is measured by the overlap of classical phase-space density and corresponding
Wigner function of the quantum system called quantum-classical fidelity (QCF).
In the analysed regime the QCF strongly deviates from the known general
behaviour in particular it decays faster then exponential. Here we study and
explain the observed behavior of the QCF and the apparent violation of the QCC
principle.Comment: 12 pages, 7 figure
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