2,159 research outputs found

### Neutrino Interactions at Low and Medium Energies

We discuss the calculations for several neutrino induced reactions from low
energies to the GeV region. Special attention is paid to nuclear corrections
when the targets are medium or heavy nuclei. Finally, we present several ratios
of neutral to charged current reactions whose values on isoscalar targets can
be estimated accurately. The ratios are useful for investigating neutrino
oscillations in Long Baseline experiments.Comment: Contributed to 1st Workshop on Neutrino - Nucleus Interactions in the
Few GeV Region (NuInt01), Tsukuba, Japan, 13-16 Dec 2001. 9 pages, 15 figure

### Muon Spectra of Quasi-Elastic and 1-Pion Production Events in LBL Neutrino Oscillation Experiments

The muon energy spectra of the quasi-elastic and 1-pion production events in
a LBL experiment, like K2K, are predicted to follow closely the neutrino energy
spectrum, with downward shifts of the energy scale by $/2 M$ and $( +
M_\Delta^2 - M^2)/2 M$ respectively. These predictions seem to agree with the
observed muon spectra in the K2K nearby detector. The corresponding muon
spectra in the far-away (SK) detector are predicted to show characteristic
spectral distortions induced by $\nu_\mu$ oscillation. Comparison of the
predicted spectral distortions with the observed muon spectra of the 1-Ring and
2-Ring muon events in the SK detector will help to determine the oscillation
parameters. The results will be applicable to other LBL experiments as well.Comment: 13 pages. One figure and a few comments added, final version to
appear in P

### Neutrino Masses and Interactions in a Model with Nambu-Goldstone Bosons

A natural scenario for the generation of neutrino masses is the see-saw
mechanism, in which a large right-handed neutrino mass makes the left-handed
neutrinos light. We review a special case when the Majorana masses originate
from spontaneous breaking of a global U(1)XU(1) symmetry. The interactions of
the right-handed with the left-handed neutrinos at the electorweak scale
further break the global symmetry giving mass to one pseudo Nambu-Goldstone
boson (pNGB). The pNGB can then generate a long-range force. Leptogenesis
occurs through decays of heavy neutrinos into the light ones and Higgs
particles. The pNGB can become the acceleron field and the neutrino masses vary
with the value of the scalar field. The talk is a brief preview of the results
in reference [11].Comment: Invited talk presented at the Second International Conference on High
Energy Physics (CICHEP II), January 14-17, 2006, Cairo, Egyp

### Throughput Optimal Routing in Overlay Networks

Maximum throughput requires path diversity enabled by bifurcating traffic at
different network nodes. In this work, we consider a network where traffic
bifurcation is allowed only at a subset of nodes called \emph{routers}, while
the rest nodes (called \emph{forwarders}) cannot bifurcate traffic and hence
only forward packets on specified paths. This implements an overlay network of
routers where each overlay link corresponds to a path in the physical network.
We study dynamic routing implemented at the overlay. We develop a queue-based
policy, which is shown to be maximally stable (throughput optimal) for a
restricted class of network scenarios where overlay links do not correspond to
overlapping physical paths. Simulation results show that our policy yields
better delay over dynamic policies that allow bifurcation at all nodes, such as
the backpressure policy. Additionally, we provide a heuristic extension of our
proposed overlay routing scheme for the unrestricted class of networks

### Fast reoptimization for the minimum spanning tree problem

AbstractWe study reoptimization versions of the minimum spanning tree problem. The reoptimization setting can generally be formulated as follows: given an instance of the problem for which we already know some optimal solution, and given some âsmallâ perturbations on this instance, is it possible to compute a new (optimal or at least near-optimal) solution for the modified instance without ex nihilo computation? We focus on two kinds of modifications: node-insertions and node-deletions. When k new nodes are inserted together with their incident edges, we mainly propose a fast strategy with complexity O(kn) which provides a max{2,3â(2/(kâ1))}-approximation ratio, in complete metric graphs and another one that is optimal with complexity O(nlogn). On the other hand, when k nodes are deleted, we devise a strategy which in O(n) achieves approximation ratio bounded above by 2â|Lmax|/2â in complete metric graphs, where Lmax is the longest deleted path and |Lmax| is the number of its edges. For any of the approximation strategies, we also provide lower bounds on their approximation ratios

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