17,556 research outputs found
Neutrino masses and R-parity violation
We review different contributions to the neutrino masses in the context of
R-parity violating supersymmetry in a basis independent manner. We comment on
the generic spectrum expected in such a scenario comparing different
contributions.Comment: Invited brief review for Mod. Phys. Lett. A, 15 pages, uses
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UPC++ v1.0 Programmer’s Guide, Revision 2020.3.0
UPC++ is a C++11 library that provides Partitioned Global Address Space (PGAS) programming. It is designed for writing parallel programs that run efficiently and scale well on distributed-memory parallel computers. The PGAS model is single program, multiple-data (SPMD), with each separate constituent process having access to local memory as it would in C++. However, PGAS also provides access to a global address space, which is allocated in shared segments that are distributed over the processes. UPC++ provides numerous methods for accessing and using global memory. In UPC++, all operations that access remote memory are explicit, which encourages programmers to be aware of the cost of communication and data movement. Moreover, all remote-memory access operations are by default asynchronous, to enable programmers to write code that scales well even on hundreds of thousands of cores
The energy flux into a fluidized granular medium at a vibrating wall
We study the power input of a vibrating wall into a fluidized granular
medium, using event driven simulations of a model granular system. The system
consists of inelastic hard disks contained between a stationary and a vibrating
elastic wall, in the absence of gravity. Two scaling relations for the power
input are found, both involving the pressure. The transition between the two
occurs when waves generated at the moving wall can propagate across the system.
Choosing an appropriate waveform for the vibrating wall removes one of these
scalings and renders the second very simple.Comment: 5 pages, revtex, 7 postscript figure
Exchange biasing of single-domain Ni nanoparticles spontaneously grown in an antiferromagnetic MnO matrix
Exchange biased composites of ferromagnetic single-domain Ni nanoparticles
embedded within large grains of MnO have been prepared by reduction of
NiMnO phases in flowing hydrogen. The Ni precipitates are 15-30
nm in extent, and the majority are completely encased within the MnO matrix.
The manner in which the Ni nanoparticles are spontaneously formed imparts a
high ferromagnetic- antiferromagnetic interface/volume ratio, which results in
substantial exchange bias effects. Exchange bias fields of up to 100 Oe are
observed, in cases where the starting Ni content in the precursor
NiMnO phase is small. For particles of approximately the same
size, the exchange bias leads to significant hardening of the magnetization,
with the coercive field scaling nearly linearly with the exchange bias field.Comment: 6 pages PDFLaTeX with 9 figure
Leptonic Flavor and CP Violation
We discuss how neutrino oscillation experiments can probe new sources of
leptonic flavor and CP violation.Comment: 8 pages, latex, no figures. Invited talk given at KAON 2001, Pisa,
Italy, June 12 - 17, 200
Organization of Multinational Activities and Ownership Structure
We develop a model in which multinational investors decide about the modes of organization, the locations of production, and the markets to be served. Foreign investments are driven by market-seeking and cost-reducing motives. We further assume that investors face costs of control that vary among sectors and increase in distance. The results show that (i) production intensive sectors are more likely to operate a foreign business independent of the investment motive, (ii) that distance may have a non-monotonous effect on the likelihood of horizontal investments, and (iii) that globalization, if understood as reducing distance, leads to more integration
New scalar resonances from sneutrino-Higgs mixing in supersymmetry with small lepton number (R-parity) violation
We consider new s-channel scalar exchanges in top quark and massive
gauge-bosons pair production in e+e- collisions, in supersymmetry with a small
lepton number violation. We show that a soft bilinear lepton number violating
term in the scalar potential which mixes the Higgs and the slepton fields can
give rise to a significant scalar resonance enhancement in e+e- -> ZZ, W+W- and
in e+e- -> t t(bar). The sneutrino-Higgs mixed state couples to the incoming
light leptons through its sneutrino component and to either the top quark or
the massive gauge bosons through its Higgs component. Such a scalar resonance
in these specific production channels cannot result from trilinear Yukawa-like
R-parity violation alone, and may, therefore, stand as strong evidence for the
existence of R-parity violating bilinears in the supersymmetric scalar
potential. We use the LEP2 measurements of the WW and ZZ cross-sections to
place useful constrains on this scenario, and investigate the expectations for
the sensitivity of a future linear collider to these signals. We find that
signals of these scalar resonances, in particular in top-pair production, are
well within the reach of linear colliders in the small lepton number violation
scenario.Comment: 22 pages in revtex, 10 figures embadded in the text using epsfi
On the Neutral Scalar Sector of the General R-parity Violating MSSM
Starting out from the most general, gauge invariant and renormalizable scalar
potential of the R-parity violating MSSM and performing a calculable rotation
to the scalar fields we arrive at a basis where the sneutrino VEVs are zero.
The advantage of our rotation is that, in addition, we obtain diagonal soft
supersymmetry breaking sneutrino masses and all potential parameters and VEVs
real, proving that the MSSM scalar potential does not exhibit spontaneous or
explicit CP-violation at tree level. The model has five CP-even and four CP-odd
physical neutral scalars, with at least one CP-even scalar lighter than M_Z. We
parametrise the neutral scalar sector in a way that resembles the
parametrisation of the R-parity conserving MSSM, analyze its mass spectrum, the
coupling to the gauge sector and the stability of the potential.Comment: 19 pages, minor changes, published version to appear in PL
Quantum SUSY signatures in low and high energy processes
In the search for phenomenological evidence of supersymmetry through the
indirect method of quantum signatures, it is useful to seek correlations of the
non-standard quantum effects in low and high energy proceses, such as those
involving on one hand the properties of the B-mesons and on the other hand the
physics of the top quark and of the Higgs bosons. There are regions of the MSSM
parameter space where the potential quantum SUSY signatures in the two energy
regimes are strongly interwoven and therefore the eventual detection of these
correlated quantum effects would strongly point towards the existence of
underlying supersymmetric dynamics.Comment: 17 pages, LaTeX, 7 figs included with epsfig. Talk at the 5th
International Workshop on High Energy Physics Phenomenology (WHEPP-5). To
appear in the Proceeding
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