Hints for the existence of hexaquark states in the baryon-antibaryon sector

The discovery of some baryon-antibaryon resonances has led us to consider 3q~3\bar{q} systems as possible candidates. We predict their spectrum in the framework of a constituent model, where the chromo-magnetic interaction plays the main role. The relevant parameters are fixed by the present knowledge on tetraquarks. The emerging scenario complies well with experiment. Besides the description of the baryon-antibaryon resonances, we find evidence for new tetraquark states, namely the a0(Y) in the hidden strangeness sector and, in the cs\bar{c}\bar{s} sector, the Y(4140) and the X(4350). A detailed account of the spectra and the decay channels is provided for future comparisons with data.Comment: 17 page

SO(10)-Inspired See-Saw Mechanism

We determine the nu_{R} Majorana mass matrix from the experimental data on neutrino oscillations in the framework of a see-saw SO(10) model, where we impose the condition (M^R)_{33} = 0 to avoid too large fine-tunings in the see-saw formula. We find a class of solutions with the two lowest neutrino masses almost degenerate and the scale of the matrix elements of M^R in the range 10^{11} -10^{12} GeV in agreement with Pati-Salam intermediate symmetry. We find also solutions with smaller neutrino masses, for which the scale of M_R depends on the solution to the "solar neutrino problem" and on the value of the component of \nu_e along the highest mass eigenstate, U_{e3}.Comment: 16 pages, 3 tables, Late

Neutrino masses and mixings in SO(10)

Assuming a Zee-like matrix for the right-handed neutrino Majorana masses in the see-saw mechanism, one gets maximal mixing for vacuum solar oscillations, a very small value for $U_{e3}$ and an approximate degeneracy for the two lower neutrino masses. The scale of right-handed neutrino Majorana masses is in good agreement with the value expected in a SO(10) model with Pati-Salam SU(4)\ts SU(2)\ts SU(2) intermediate symmetry.Comment: 11 pages, no figures. References adde

Selection and Characterisation of Transformed BHK21 Cells Altered in Response to Fibronectin

I found that selection of cell lines which do not respond to fibronectin was easy from polyoma transformed cells, but yielded no such cell lines from Schmidt-Ruppin transformed cells. Mixing of Py3 mutants (F2) with SR-WT cells showed that Py3 mutants could be recovered when present at about 1:10 6 and higher inputs, while the frequency of SR mutants was zero. Cells with a genetic marker (resistance to 6-thioguanine) were isolated from polyoma transformed cells. Two colonies were selected (TG1, TG2). From one of these lines (TG2), two different low adherent lines both deficient in response to fibronectin, were selected and recloned on soft agar. Variant 1 (TG2F1) has compact colonies of rounded cells while variant 2 (TG2F2) has scattered colonies with a few slightly spread cells. Both are resistant to 6-thioguanine and have undetectable HGPRT-ase activity. Revertants of two different morphologies were isolated from the compact colony Py3 mutant (F2). Variant 1 (F2R1) has well spread cells while cells of variant 2 (F2R2) are less well spread. Both revertants were found to attach and spread on fibronectin-coated surfaces. A third type of revertant has been observed several times, which had extremely well spread cells, better spread than wild type. Attempts to isolate this type of revertant were unsuccessful. TG mutants (TG2F1 & TG2F2) were found to spread on Con A but not on WGA-coated surfaces. On poly L-lysine, both wild type and mutants adhere, but none of them spread. Wild type but not mutants spread fully on poly L-lysine in presence of 1% serum. Mutants did not spread on serum or fibronectin. Mn2+ ions were effective in inducing the spreading of TG2-WT and both variants. 10 -6 M Mn2+ was 50% effective in inducing the spreading of TG-WT on fibronectin while 10 -3 M was 50% effective on haemoglobin. Higher concentrations such as 10 -2 M were required for TG2F1 cells on both surfaces. 10 -4 M was effective with TG2F2 cells on fibronectin while 10 -3 M was effective on haemoglobin. Mg2+ at 10 -2 M was as effective as Mn2+ with parental cells on fibronectin but not as effective as Mn2+ with variants on either surfaces. Co2+ was less effective at 10 -2 M with all cell lines compared to Mn 2+ or Mg2+. Analysis of lectin binding proteins associated with the detergent soluble extracts of Py3 (NaDOC-solubilised membranes and Triton extracts) failed to reveal differences between wild type, mutants and revertants. The molecular basis for the differences between wild type and mutants could be in the fibronectin receptor, or in signal transduction required to induce the spreading response, but remains unidentified

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

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

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

From the granular Leidenfrost state to buoyancy-driven convection

Grains inside a vertically vibrated box undergo a transition from a density-inverted and horizontally homogeneous state, referred to as the granular Leidenfrost state, to a buoyancy-driven convective state. We perform a simulational study of the precursors of such a transition and quantify their dynamics as the bed of grains is progressively fluidized. The transition is preceded by transient convective states, which increase their correlation time as the transition point is approached. Increasingly correlated convective flows lead to density fluctuations, as quantified by the structure factor, that also shows critical behavior near the transition point. The amplitude of the modulations in the vertical velocity field are seen to be best described by a quintic supercritical amplitude equation with an additive noise term. The validity of such an amplitude equation, and previously observed collective semiperiodic oscillations of the bed of grains, suggests a new interpretation of the transition analogous to a coupled chain of vertically vibrated damped oscillators. Increasing the size of the container shows metastability of convective states, as well as an overall invariant critical behavior close to the transition