1,114 research outputs found
On Neutrinos and Fermionic Mass Patterns
Recent data on neutrino mass differences are consistent with a hierarchical
neutrino mass structure strikingly similar to what is observed for the other
fermionic masses.Comment: 8pages, 2figure
Twenty years of punishment (and democracy) in South Africa: The pitfalls of governing crime through the community
This article examines how the ideology of ‘community’ is deployed to govern crime in South Africa, both by marginalised black communities and by the government. Although the turn to ‘community’ started under theNational Party government in the late 1970s, there is no doubt that as a site, technology, discourse, ideology and form of governance, ‘community’ has become entrenched in the post-1994 era. Utilising empirical data drawn from ethnographic research on vigilantism in Khayelitsha, as well as archival materials in respect of ANC policies and practices before it became the governing party, I argue that rallying ‘communities’ around crime combatting has the potential to unleash violent technologies in the quest for ‘ethics’ and ‘morality’. When community members unite against an outsider they are bonded for an intense moment in a way that masks thevery real problems that tear the community apart. Because violent punishment is one of the consequences of the state’s turn towards democratic localism, we should question the way in which the ‘community’ is deployed as a tool of crime prevention, and subject it to rigorous scrutin
Constructing Dirac linear fermions in terms of non-linear Heisenberg spinors
We show that the massive (or massless) neutrinos can be described as special
states of Heisenberg nonlinear spinors. As a by-product of this decomposition a
particularly attractive consequence appears: the possibility of relating the
existence of only three species of mass-less neutrinos to such internal
non-linear structure. At the same time it allows the possibility that neutrino
oscillation can occurs even for massless neutrinos
Symmetries, Large Leptonic Mixing and a Fourth Generation
We show that large leptonic mixing occurs most naturally in the framework of
the Sandard Model just by adding a fourth generation. One can then construct a
small discrete symmetry, instead of the large ,
which requires that the neutrino as well as the charged lepton mass matrices be
proportional to a democratic mass matrix, where all entries are
equal to unity. Without considering the see-saw mechanism, or other more
elaborate extensions of the SM, and contrary to the case with only 3
generations, large leptonic mixing is obtained when the symmetry is broken.Comment: 6 pages, ReVTeX, no figure
A robust subspace based approach to feedforward control of broadband disturbances on a six-degrees-of-freedom vibration isolation set-up
The contribution of this paper is twofold. First, the paper introduces a novel hybrid vibration isolation approach which uses a combination of passive and active vibration control techniques to provide additional design freedom. The approach can be used to meet higher design requirements with respect to vibration isolation. To illustrate the feasibility of the approach, a stiff hybrid sixdegrees-of-freedom vibration isolation set-up will be presented. The objective of the set-up is to investigate if the receiver structure can be isolated from the source structure by six hybrid vibration isolation mounts, such that disturbances induced by the source structure are isolated from the receiver structure. Vibration isolation is established by minimizing signals from six acceleration sensor outputs and by steering six piezo-electric actuator inputs. Our second contribution is that a state space based fixed gain H2 controller is designed, implemented and validated. Real-time broadband feedforward control results are presented (between 0 - 1 kHz) which show that an average reduction of 8.0 dB is achieved in the error sensor outputs in real-time
Neutrino mixing and CP violation from Dirac-Majorana bimaximal mixture and quark-lepton unification
We demonstrate that only two ansatz can produce the features of the neutrino
mixing angles. The first ansatz comes from the quark-lepton grand unification;
is satisfied for left-handed neutrinos, where
are the Dirac mass eigenstates and are the flavour
eigenstates. The second ansatz comes from the assumption; is satisfied between the Dirac mass eigenstates
and the light Majorana neutrino mass eigenstates , where
is the bimaximal mixing matrix. By these two ansatz, the
Maki-Nakagawa-Sakata matrix is given by . We find that in this model the novel relation is satisfied, where and are
solar and CHOOZ angle respectively. This "Solar-CHOOZ Complementarity" relation
indicates that only if the CHOOZ angle is sizable, the solar
angle can deviate from the maximal mixing. We also infer the CP
violation in neutrino oscillations. The leptonic Dirac CP phase
is predicted as , where are the CKM parameters in Wolfenstein parametrization. Furthermore, we
remark that the ratio of the Jarlskog CP violation factor for quarks and
leptons is important, because the large uncertainty on is cancelled out
in the ratio, .Comment: 9 pages, no figures; v2 references added, v3 references adde
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