216 research outputs found
The Liverpool Statement 2005: Priorities for the European Union/United States Spiral Computed Tomography Collaborative Group
The Liverpool Statement 2005 was developed at the Fourth International Lung Cancer Molecular Biomarkers Workshop in Liverpool (October 27-29, 2005) and focused on the priorities for the European Union/United States (EU-US) Spiral Computed Tomography (CT) Collaborative Group. The application of spiral CT technology for early lung cancer screening has gained enormous momentum in the past 5 years. The EU-US Spiral CT Collaboration was initiated in 2001 in Liverpool, and subsequent meetings throughout Europe have resulted in the development of collaborative protocols and minimal data sets that provide a mechanism for the different trial groups to work together, with the ultimate aim to pool results. Considerable progress has been made with major national screening trials in the U.S. and Europe, which include IELCAP, NLST, and NELSON. The major objective of this international collaboration is the planned cross-analysis of the individual studies after they are reported. The EU-US researchers have agreed to a number of long-term objectives and to explore strategic areas for harmonization of complementary investigations
Competition between spin and charge polarized states in nanographene ribbons with zigzag edges
Effects of the nearest neighbor Coulomb interaction on nanographene ribbons
with zigzag edges are investigated using the extended Hubbard model within the
unrestricted Hartree-Fock approximation. The nearest Coulomb interaction
stabilizes a novel electronic state with the opposite electric charges
separated and localized along both edges, resulting in a finite electric dipole
moment pointing from one edge to the other. This charge-polarized state
competes with the peculiar spin-polarized state caused by the on-site Coulomb
interaction and is stabilized by an external electric field.Comment: 4 pages; 4 figures; accepted for publication in Phys. Rev. B; related
Web site: http://staff.aist.go.jp/k.harigaya/index_E.htm
Hamiltonian BRST-anti-BRST Theory
The hamiltonian BRST-anti-BRST theory is developed in the general case of
arbitrary reducible first class systems. This is done by extending the methods
of homological perturbation theory, originally based on the use of a single
resolution, to the case of a biresolution. The BRST and the anti-BRST
generators are shown to exist. The respective links with the ordinary BRST
formulation and with the -covariant formalism are also established.Comment: 34 pages, Latex fil
Leptogenesis, CP violation and neutrino data: What can we learn?
A detailed analytic and numerical study of baryogenesis through leptogenesis
is performed in the framework of the standard model of electroweak interactions
extended by the addition of three right-handed neutrinos, leading to the seesaw
mechanism. We analyze the connection between GUT-motivated relations for the
quark and lepton mass matrices and the possibility of obtaining a viable
leptogenesis scenario. In particular, we analyze whether the constraints
imposed by SO(10) GUTs can be compatible with all the available solar,
atmospheric and reactor neutrino data and, simultaneously, be capable of
producing the required baryon asymmetry via the leptogenesis mechanism. It is
found that the Just-So^2 and SMA solar solutions lead to a viable leptogenesis
even for the simplest SO(10) GUT, while the LMA, LOW and VO solar solutions
would require a different hierarchy for the Dirac neutrino masses in order to
generate the observed baryon asymmetry. Some implications on CP violation at
low energies and on neutrinoless double beta decay are also considered.Comment: 36 pages, 6 figures; new references added, final version to appear in
Nucl. Phys.
What can we learn from neutrinoless double beta decay experiments?
We assess how well next generation neutrinoless double beta decay and normal
neutrino beta decay experiments can answer four fundamental questions. 1) If
neutrinoless double beta decay searches do not detect a signal, and if the
spectrum is known to be inverted hierarchy, can we conclude that neutrinos are
Dirac particles? 2) If neutrinoless double beta decay searches are negative and
a next generation ordinary beta decay experiment detects the neutrino mass
scale, can we conclude that neutrinos are Dirac particles? 3) If neutrinoless
double beta decay is observed with a large neutrino mass element, what is the
total mass in neutrinos? 4) If neutrinoless double beta decay is observed but
next generation beta decay searches for a neutrino mass only set a mass upper
limit, can we establish whether the mass hierarchy is normal or inverted? We
base our answers on the expected performance of next generation neutrinoless
double beta decay experiments and on simulations of the accuracy of
calculations of nuclear matrix elements.Comment: Added reference
Protecting the primordial baryon asymmetry in the seesaw model compatible with WMAP and KamLAND
We require that the primordial baryon asymmetry is not washed out in the
seesaw model compatible with the recent results of WMAP and the neutrino
oscillation experiments including the first results of KamLAND. We find that
only the case of the normal neutrino mass hierarchy with an approximate
-symmetry satisfies the requirement. We further derive, depending on the
signs of neutrino mass eigenvalues, three types of neutrino mass matrixes,
where the values of each element are rather precisely fixed.Comment: 21pages; added reference
The Majorana neutrino masses, neutrinoless double beta decay and nuclear matrix elements
The effective Majorana neutrino mass is evaluated by using the latest results
of neutrino oscillation experiments. The problems of the neutrino mass
spectrum,absolute mass scale of neutrinos and the effect of CP phases are
addressed. A connection to the next generation of the neutrinoless double beta
decay (0nbb-decay) experiments is discussed. The calculations are performed for
76Ge, 100Mo, 136Xe and 130Te by using the advantage of recently evaluated
nuclear matrix elements with significantly reduced theoretical uncertainty. An
importance of observation of the 0nbb-decay of several nuclei is stressed.Comment: 29 pages, 5 figures, EXO (10 t) experiment considere
Thermal leptogenesis in a model with mass varying neutrinos
In this paper we consider the possibility of neutrino mass varying during the
evolution of the Universe and study its implications on leptogenesis.
Specifically, we take the minimal seesaw model of neutrino masses and introduce
a coupling between the right-handed neutrinos and the dark energy scalar field,
the Quintessence. In our model, the right-handed neutrino masses change as the
Quintessence scalar evolves. We then examine in detail the parameter space of
this model allowed by the observed baryon number asymmetry. Our results show
that it is possible to lower the reheating temperature in this scenario in
comparison with the case that the neutrino masses are unchanged, which helps
solve the gravitino problem. Furthermore, a degenerate neutrino mass patten
with larger than the upper limit given in the minimal leptogenesis
scenario is permitted.Comment: 18 pages, 7 figures, version to appear in PR
Standalone vertex ďŹnding in the ATLAS muon spectrometer
A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at âs = 7 TeV collected with the ATLAS detector at the LHC during 2011
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