8,459 research outputs found
Charm, Beauty and Top at HERA
Results on open charm and beauty production and on the search for top
production in high-energy electron-proton collisions at HERA are reviewed. This
includes a discussion of relevant theoretical aspects, a summary of the
available measurements and measurement techniques, and their impact on improved
understanding of QCD and its parameters, such as parton density functions and
charm- and beauty-quark masses. The impact of these results on measurements at
the LHC and elsewhere is also addressed.Comment: 103 pages, 60 figures, to be published in Prog. Part. Nucl. Phy
The MONOLITH project
MONOLITH is a proposed massive (34 kt) magnetized tracking calorimeter at the
Gran Sasso laboratory in Italy, optimized for the detection of atmospheric muon
neutrinos. The main goal is to establish (or reject) the neutrino oscillation
hypothesis through an explicit observation of the full first oscillation swing.
The Delta m^2 sensitivity range for this measurement comfortably covers the
complete Super-Kamiokande allowed region. Other measurements include studies of
matter effects and the NC/CC and anti-nu/nu ratio, the study of cosmic ray
muons in the multi-TeV range, and auxiliary measurements from the CERN to Gran
Sasso neutrino beam. Depending on approval, data taking with part of the
detector could start in 2004. The detector and its performance are described,
and its potential later use as a neutrino factory detector is addressed.Comment: 6 pages. Contribution to NUFACT'00 neutrino factory workshop,
Monterey, CA, USA, May 22-26, 200
Pseudo-Dirac neutrinos as a potential complete solution to the neutrino oscillation puzzle
A solution for the neutrino mass and mixing pattern is proposed which is compatible with all available experimental data on neutrino oscillations. This solution involves Majorana neutrinos of the pseudo-Dirac type, i.e. . The solar and atmospheric neutrino observations are mainly explained as and oscillations, w here S indicates the sterile (``righthanded'') partner of each neutrino generation, while the LSND result is interpreted in terms of standard oscillations. The resulting constrai nts on and oscillations are also discussed. This solution leaves room for a hierarchical mass and mixing scheme with a mass in the few eV r ange, as favoured by some dark matter scenarios. The apparent conflict with standard Big Bang nucleosynthesis is addressed and the implications for current and future experiments are discussed. I t is argued that both short and long baseline accelerator neutrino experiments are needed in order to decide between this solution and other oscillation scenarios
Summary of the NOW'98 Phenomenology Working Group
Summary of the Phenomenology Working Group at the Europhysics Neutrino
Oscillation Workshop (NOW'98), 7-9 September 1998, Amsterdam.Comment: 66 page
Future Atmospheric Neutrino Detectors
Future experiments focusing on atmospheric neutrino detection are reviewed.
One of the main goals of these experiments is the detection of an unambiguous
oscillation pattern (nu_mu reappearance) to prove the oscillation hypothesis.
Further goals include the discrimination of nu_mu - nu_tau and nu_mu -
nu_sterile oscillations, and the detection of a potential small nu_mu - nu_e
contribution. The search for matter effects in three or more flavour
oscillations can be used to constrain hybrid oscillation models and potentially
measure the sign of delta m^2. The detectors and measurement techniques
proposed to achieve these goals are described, and their physics reach is
discussed.Comment: 9 pages, invited talk at the XIX International Conference on Neutrino
Physics and Astrophysics, Sudbury, Canada, June 16-21, 2000, to appear in
Nucl. Phys. B (Proc. Suppl.
Prompt neutrino fluxes in the atmosphere with PROSA parton distribution functions
Effects on atmospheric prompt neutrino fluxes of present uncertainties
affecting the nucleon composition are studied by using the PROSA fit to parton
distribution functions (PDFs). The PROSA fit extends the precision of the PDFs
to low x, which is the kinematic region of relevance for high-energy neutrino
production, by taking into account LHCb data on charm and bottom
hadroproduction. In the range of neutrino energies explored by present Very
Large Volume Neutrino Telescopes, it is found that PDF uncertainties are far
smaller with respect to those due to renormalization and factorization scale
variation and to assumptions on the cosmic ray composition, which at present
dominate and limit our knowledge of prompt neutrino fluxes. A discussion is
presented on how these uncertainties affect the expected number of atmospheric
prompt neutrino events in the analysis of high-energy events characterized by
interaction vertices fully contained within the instrumented volume of the
detector, performed by the IceCube collaboration.Comment: 36 pages, 17 figures, 1 tabl
Forest related interventions and the stakeholders of forests in the Northwest Frontier Province of Pakistan
The forests of the North-West Frontier Province (NWFP) of Pakistan are vanishing at a high rate in spite of more than two decades of donor led interventions and extensive forest governance systems led by the state. Failure of most of the forest related projects and policies in meeting their intended objectives calls for searching out the underlying causes of the ineffectiveness of such interventions. Many development researchers have stressed the importance of stakeholder analysis. A holistic analysis of stakeholders, conflicts and power relations is an essential step to ensure the sustainability of development interventions and active participation of local actors. A wide range of actors can influence or be influenced by any forest related intervention in the NWFP. This paper, therefore, presents an exploratory analysis of the stakeholders' characteristics, power relations and conflicts in the context of
interventions in the forestry sector of the NWFP. Various groups of stakeholders, for example, local communities, civil society organizations, religious and traditional institutions, state agencies, global actors, etc., are trying to operate within the contested political arena of the NWFP. This paper shows that on the one hand, the state as well as donor led interventions do not really engage in a meaningful dialogue with local stakeholders and institutions, and on the other hand, these entities themselves are not in a position to initiate a change in the local resource use. Thus, a way forward is seen in fostering a dialogue among key stakeholders
Coupling of THz radiation with intervalence band transitions in microcavities
The strong coupling of THz radiation and material excitations can improve the quantum efficiency of THz emitters. In this paper, we investigate THz polaritons and antipolaritons based on valence band transitions, which allow TE coupling in a simple configuration. The approach can improve the quantum efficiency of THz based devices based on TE mode in the strong coupling regime of THz radiations and intervalence bands transitions in a GaAs/AlGaAs quantum wells. A Nonequilibrium Many Body Approach for the optical response beyond the Hartree-Fock approximation is used as input to the effective dielectric function formalism for the polariton/antipolariton problem. The energy dispersion relations in the THz range are obtained by adjusting the full numerical solutions to simple analytical expressions, which can be used for non specialists in a wide number of new structures and material systems. The combination of manybody and nonparabolicity at high densities leads to dramatic changes in the polariton spectra in a nonequilibrium configuration, which is only possible for intervalence band transitions
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