The longitudinal and transverse responses in the inclusive electron scattering: a functional approach

The splitting between the charge-longitudinal and spin-transverse responses is explained in a model whose inputs are the effective interactions in the particle-hole channels in the frame of the first order boson loop expansion. It is shown that the interplay between $\omega$-meson exchange and box diagrams (two-meson exchange with simultaneous excitation of one or two nucleons to $\Delta$'s) mainly rules the longitudinal response, while in the transverse one the direct $\Delta$ excitations almost cancel the one-loop correction and the response is mainly governed by the $\rho$-meson rescattering inside the nucleus. It is also shown that a small variation in the nuclear densities may explain the observed discrepancies between different nuclei.Comment: LaTex2e file with 53 .ps figures; submitted to Nucl. Phys

Quantum Interference of Force

We show that a quantum particle subjected to a positive force in one path of a Mach-Zehnder interferometer and a null force in the other path may receive a negative average momentum transfer when it leaves the interferometer by a particular exit. In this scenario, an ensemble of particles may receive an average momentum in the opposite direction of the applied force due to quantum interference, a behavior with no classical analogue. We discuss some experimental schemes that could verify the effect with current technology, with electrons or neutrons in Mach-Zehnder interferometers in free space and with atoms from a Bose-Einstein condensate.Comment: 5 figures. Accepted in Quantum on 2018-12-0

Spin and rotational symmetries in unrestricted Hartree Fock states of quantum dots

Ground state energies are obtained using the unrestricted Hartree Fock method for up to four interacting electrons parabolically confined in a quantum dot subject to a magnetic field. Restoring spin and rotational symmetries we recover Hund first rule. With increasing magnetic field, crossovers between ground states with different quantum numbers are found for fixed electron number that are not reproduced by the unrestricted Hartree Fock approximation. These are consistent with the ones obtained with more refined techniques. We confirm the presence of a spin blockade due to a spin mismatch in the ground states of three and four electrons.Comment: 16 Pages, 2 figures, accepted for publication on New Journal of Physic

INFESTATION RATE OF BRANCHIOBDELLIDS IN AUSTROPOTAMOBIUS PALLIPES ITALICUS FROM A STREAM OF CENTRAL ITALY: PRELIMINARY RESULTS

Species identity, infestation rate and distribution over the host body of branchiobdellids (Annelida, Clitellata) have been analysed in an Austropotamobius pallipes italicus population from the National Park of the Foreste Casentinesi, Monte Falterona and Campigna (central Italy). Branchiobdella italica - the nearly unique species present in our samples - did not differ in its occurrence among the size classes of its host, while female crayfish showed a significantly higher infestation rate than the other sex. Branchiobdellids were mostly found on gill chambers and cephalothorax base, and only in the case of larger crayfish and males did they occupy other body areas

Functional approach to the electromagnetic response function: the Longitudinal Channel

In this paper we address the (charge) longitudinal electromagnetic response for a homogeneous system of nucleons interacting via meson exchanges in the functional framework. This approach warrants consistency if the calculation is carried on order-by-order in the mesonic loop expansion with RPA-dressed mesonic propagators. At the 1-loop order and considering pion, rho and omega exchanges we obtain a quenching of the response, in line with the experimental results.Comment: RevTeX, 18 figures available upon request - to be published in Physical Review