Flavour-conserving oscillations of Dirac-Majorana neutrinos

We analyze both chirality-changing and chirality-preserving transitions of Dirac-Majorana neutrinos. In vacuum, the first ones are suppressed with respect to the others due to helicity conservation and the interactions with a (``normal'') medium practically does not affect the expressions of the probabilities for these transitions, even if the amplitudes of oscillations slightly change. For usual situations involving relativistic neutrinos we find no resonant enhancement for all flavour-conserving transitions. However, for very light neutrinos propagating in superdense media, the pattern of oscillations $\nu_L \to \nu^C_L$ is dramatically altered with respect to the vacuum case, the transition probability practically vanishing. An application of this result is envisaged.Comment: 14 pages, latex 2E, no figure

W-algebras from symplectomorphisms

It is shown how $W$-algebras emerge from very peculiar canonical transformations with respect to the canonical symplectic structure on a compact Riemann surface. The action of smooth diffeomorphisms of the cotangent bundle on suitable generating functions is written in the BRS framework while a $W$-symmetry is exhibited. Subsequently, the complex structure of the symmetry spaces is studied and the related BRS properties are discussed. The specific example of the so-called $W_3$-algebra is treated in relation to some other different approaches.Comment: LaTex, 25 pages, no figures, to appear in Journ. Math. Phy

Non Abelian TQFT and scattering of self dual field configuration

A non-abelian topological quantum field theory describing the scattering of self-dual field configurations over topologically non-trivial Riemann surfaces, arising from the reduction of 4-dim self-dual Yang-Mills fields, is introduced. It is shown that the phase space of the theory can be exactly quantized in terms of the space of holomorphic structures over stable vector bundles of degree zero over Riemann surfaces. The Dirac monopoles are particular static solutions of the field equations. Its relation to topological gravity is discussed.Comment: 13 pages, Late

Discovery potential for New Physics in view of the RHIC-Spin upgrade

In view of a possible upgrade of the RHIC-Spin program at BNL, concerning both the machine and the detectors, we give some predictions concerning the potentialities of New Physics detection with polarized proton beams. We focus on parity-violating asymmetries in one-jet production due to contact terms or to a new leptophobic neutral gauge boson. We comment on the main uncertainties and we compare with unpolarized searches at Tevatron.Comment: Latex file, 9 pages and 1 ps fig included with psfig.st

Discovery limits for a new contact interaction at future hadronic colliders with polarized beams

The production of high-transverse energy jets in hadron-hadroncollisions is sensitive to the presence of new contact interactions between quarks. If proton polarization were available, the measurement of some parity violating spin asymmetries in one-jet production at large transverse energy would complement the usual search for deviations from the expected QCD cross section. In the same time, a unique information on the chirality structure of the new interaction could be obtained. In this context, we compare the potentialities of various $pp$ and $p\bar p$ colliders that are planned or have been proposed, with the additional requirement of beam polarization.Comment: Latex file, 9 pages and 1 ps fig, definition of the subprocess variables and one example of the effect of new contact terms on the parity violating spin asymmetry are added. Eq. 8 (now eq. 9) and the following equation are changed, giving better bounds in the polarized pp case (new figure

Idade, peso e prenhez de novilhas Nelore mocha.

Objetivou-se com este trabalho caracterizar idade, peso e prenhez em novilhas Nelore. Utilizou-se 56 novilhas da raça Nelore, desafiadas com touros para a determinação da idade a primeira prenhez. As novilhas foram pesadas a cada dois meses dos 16 aos 32 meses de idade. Os resultados evidenciaram idade média de 24,10 ± 5,13 meses e peso médio de 304,83 ± 48,23 kg nas 37 novilhas prenhas. Concluiu-se que a idade a primeira prenhez das novilhas Nelore observada neste experimento encontra-se próxima ao descrito na literatura para fêmeas zebuínas, havendo a necessidade de maiores estudos, relacionados ao melhoramento genético e/ou alternativas de manejo, a fim de antecipar a ocorrência da primeira prenhez

Decomposition of Hilbert space in sets of coherent states

Within the generalized definition of coherent states as group orbits we study the orbit spaces and the orbit manifolds in the projective spaces constructed from linear representations. Invariant functions are suggested for arbitrary groups. The group SU(2) is studied in particular and the orbit spaces of its j=1/2 and j=1 representations completely determined. The orbits of SU(2) in CP^N can be either 2 or 3 dimensional, the first of them being either isomorphic to S^2 or to RP^2 and the latter being isomorphic to quotient spaces of RP^3. We end with a look from the same perspective to the quantum mechanical space of states in particle mechanics.Comment: revtex, 13 pages, 12 figure