The baryon content of the Universe

The large discrepancy between the amount of baryons that were synthesized in Big-Bang and that we detect at $z=0$ locked in stars inside galaxies and in hot/cold gas in galaxies. goup and clusters, is a well known crucial issue for present day cosmology. It is also thought that this riddle is at the backbone of how the ordinary matter has formed, inside dark potential wells, the structures we see today. Then, it is useful to reprint, by means of this archive, the first (pre- astro-ph era) published work in which the amount of "luminous" baryons was actually and suitably computed and the disagreement with the BBN predictions strongly claimed. This because 12 years after the method and the results are still up-to-date, and above all, people are occasionally found to know only later works (appeared on astro-ph) that were meant to be just (ours or other's) follow ups of the present paper.Comment: 5 page

ROTATION CURVES OF 967 SPIRAL GALAXIES

We present the rotation curves (RCs) of 967 spiral galaxies, obtained by folding and deprojecting the raw optical data by Mathewson et al. (1992). Out of these, we have identified 80 excellent RCs and 820 fair RCs. The 80 excellent RCs are smooth, symmetric, have negligible rms internal error, extend to at least the optical radius, and have high and homogeneus radial data coverage; they rival with the best optical one-slit RCs available in the literature and are ideally suited for detailed mass structure modelling. The 820 fair RCs do not meet at least one of the above criteria and hence are not suitable for direct mass modelling; however, they constitute a large database for methods aiming to recover statistical properties of DM. For these 900 RCs we also present, in figures and tables, the rotation curves smoothed on scales corresponding to 5%-20% of the optical size. By size, homogeneity, intrinsic quality, and spanned range of luminosities and asymptotic velocities, this sample constitutes by far the best sample of RCs available to date. As such, it will offer a unique opportunity for investigating in considerable depth the properties of DM in galaxies. The the deprojected folded curves, the smoothed curves, and various related quantities are available via anonymous ftp at galileo.sissa.it in the directory /users/ftp/pub/psrot.Comment: text in plain TeX (10 pages), with no tables and figures. Preprints are available directly from the Authors ([email protected]; [email protected]). To appear in Ap.J. Suppl

Lagrangian Theory of Constrained Systems: Cosmological Application

Previous work in the literature has studied the Hamiltonian structure of an R-squared model of gravity with torsion in a closed Friedmann-Robertson-Walker universe. Within the framework of Dirac's theory, torsion is found to lead to a second-class primary constraint linear in the momenta and a second-class secondary constraint quadratic in the momenta. This paper studies in detail the same problem at a Lagrangian level, i.e. working on the tangent bundle rather than on phase space. The corresponding analysis is motivated by a more general program, aiming to obtain a manifestly covariant, multisymplectic framework for the analysis of relativistic theories of gravitation regarded as constrained systems. After an application of the Gotay-Nester Lagrangian analysis, the paper deals with the generalized method, which has the advantage of being applicable to any system of differential equations in implicit form. Multiplication of the second-order Lagrange equations by a vector with zero eigenvalue for the Hessian matrix yields the so-called first-generation constraints. Remarkably, in the cosmological model here considered, if Lagrange equations are studied using second-order formalism, a second-generation constraint is found which is absent in first-order formalism. This happens since first- and second-order formalisms are inequivalent. There are, however, no {\it a priori} reasons for arguing that one of the two is incorrect. First- and second-generation constraints are used to derive physical predictions for the cosmological model.Comment: 22 pages, plain-tex, recently appearing in Nuovo Cimento B, volume 109, pages 1259-1273, December 199

On the Moduli Space of the T6/Z3T^6/Z_3 Orbifold and Its Modular Group

We describe the duality group $\Gamma=SU(3,3,Z)$ for the Narain lattice of the $T^6/Z_3$ orbifold and its action on the corresponding moduli space. A symplectic embedding of the momenta and winding numbers allows us to connect the orbifold lattice to the special geometry of the moduli space. As an application, a formal expression for an automorphic function, which is a candidate for a non--perturbative superpotential, is given.Comment: 15 page

IAU colloquium 138. Peculiar versus normal phenomena in a-type and related stars

Abstract of invited and contributed papers, May 26, 1992SIGLEITItal

Towards the classification of exactly solvable Feynman path integrals: delta-function perturbations and boundary-problems as miscellaneous solvable models

To appearSIGLEITItal

Path integral solutions of Scarf-like potentials

SIGLEITItal

Renormalization of multiple infinities and renormalization group in string loops

SIGLEITItal

Periodic solutions for some nonlinear differential equations of neutral type

SIGLEITItal

A review of neutrinos in cosmology

SIGLEITItal