Transversity studies with a polarized 3He target

A realistic study of the SiDIS process 3He(e , e π)X in the Bjorken limit is briefly reviewed, showing that the nuclear effects, present in the extraction of the neutron information, are largely under theoretical control, within an ImpulseApproximation approach. In view of the forthcoming experimental data, we shortly present a novel Poincar´e covariant description of the nuclear target, implementing a Light-Front analysis at finite Q2, within the Bakamijan-Thomas construction of the Poincar´e generators. Furthermore, as a by-product of the introduction of a LightFront spin-dependent spectral function for a J = 1/2 system, we straightforwardly extend our analysis to the quark-quark correlator, obtaining three new exact relations between the six leading-twist Transverse-Momentum–Dependent distributions

Extended Spherical Collapse and the Accelerating Universe

The influence of the shear stress and angular momentum on the nonlinear spherical collapse model is discussed in the framework of the Einstein-de Sitter (EdS) and $\Lambda$CDM models. By assuming that the vacuum component is not clustering within the homogeneous nonspherical overdensities, we show how the local rotation and shear affects the linear density threshold for collapse of the non-relativistic component ($\delta_\mathrm{c}$) and its virial overdensity ($\Delta_\mathrm{V}$). It is also found that the net effect of shear and rotation in galactic scale is responsible for higher values of the linear overdensity parameter as compared with the standard spherical collapse model (no shear and rotation).Comment: 5 pages, 2 fig

On the Stability and the Approximation of Branching Distribution Flows, with Applications to Nonlinear Multiple Target Filtering

We analyse the exponential stability properties of a class of measure-valued equations arising in nonlinear multi-target filtering problems. We also prove the uniform convergence properties w.r.t. the time parameter of a rather general class of stochastic filtering algorithms, including sequential Monte Carlo type models and mean eld particle interpretation models. We illustrate these results in the context of the Bernoulli and the Probability Hypothesis Density filter, yielding what seems to be the first results of this kind in this subject

Shear and rotation in Chaplygin cosmology

We study the effect of shear and rotation on results previously obtained dealing with the application of the spherical collapse model (SCM) to generalized Chaplygin gas (gCg) dominated universes. The system is composed of baryons and gCg and the collapse is studied for different values of the parameter $\alpha$ of the gCg. We show that the joint effect of shear and rotation is that of slowing down the collapse with respect to the simple SCM. This result is of utmost importance for the so-called unified dark matter models, since the described slow down in the growth of density perturbation can solve one of the main problems of the quoted models, namely the instability described in previous papers [e.g., H. B. Sandvik {\it et al.}, Phys. Rev. D {\bf 69}, 123524 (2004)] at the linear perturbation level.Comment: 10 pages, 4 figures. Matches published versio

Distorted spin-dependent spectral function of an A=3 nucleus and semi-inclusive deep inelastic scattering processes

The distorted spin-dependent spectral function of a nucleon inside an A = 3 nucleus is introduced as a novel tool for investigating the polarized electron scattering off polarized 3He in the semi-inclusive DIS regime (SiDIS), going beyond the standard plane-wave impulse approximation. This distribution function is applied 3⃗ ′2 to the study of the spectator SiDIS, He(e⃗,e H)X, to properly take into account the final-state interaction between the hadronizing quark and the detected deuteron, with the final goal of a more reliable extraction of the polarized parton distribution g1(x) inside a bound proton. Our analysis allows one to single out two well-defined kinematical regions where the experimental asymmetries could yield very interesting information: the region where the final-state effects can be minimized, and therefore the direct access to the parton distributions in the proton is feasible, and the one where the final-state interaction dominates, and the spectator SiDIS reactions can elucidate the mechanism of the quark hadronization itself. The perspectives of extending our approach (i) to the mirror nucleus, 3H, for achieving a less model-dependent flavor decomposition and (ii) to the asymmetries 3⃗′ measured in the standard SiDIS reactions, e⃗ + He → e + h + X, with h a detected fast hadron, with the aim of extracting the neutron transversity, are discussed