Semi-inclusive deep inelastic lepton scattering off complex nuclei

It is shown that in semi-inclusive deep inelastic scattering (DIS) of electrons off a complex nucleus A, the detection, in coincidence with the scattered electron, of a nucleus (A-1) in the ground state, as well as of a nucleon and a nucleus (A-2), also in the ground state, may provide unique information on several long standing problems, such as : i) the nature and the relevance of the final state interaction in DIS; ii) validity of the spectator mechanism in DIS; iii) the medium induced modifications of the nucleon structure function; iv) the origin of the EMC effect.Comment: Latex, 41 pages, 12 ps figures included in submission. To appear in European Physics Journal A,

The eta-photon transition form factor

The eta-photon transition form factor is evaluated in a formalism based on a phenomenological description at low values of the photon virtuality, and a QCD-based description at high photon virtualities, matching at a scale $Q_{0}^{2}$. The high photon virtuality description makes use of a Distribution Amplitude calculated in the Nambu-Jona-Lasinio model with Pauli-Villars regularization at the matching scale $Q_{0}^{2}$, and QCD evolution from $Q_{0}^{2}$ to higher values of $Q^{2}$. A good description of the available data is obtained. The analysis indicates that the recent data from the BaBar collaboration on pion and eta transition form factor can be well reproduced, if a small contribution of twist three at the matching scale $Q_{0}^{2}$ is included.Comment: 14 pages, 3 figures, revised version, minor corrections, references added, conclusions unchanged. Accepted for publication in Phys. Rev.

Analyzing the Boer-Mulders function within different quark models

A general formalism for the evaluation of time reversal odd parton distributions is applied here to calculate the Boer-Mulders function. The same formalism when applied to evaluate the Sivers function led to results which fulfill the Burkardt sum rule quite well. The calculation here has been performed for two different models of proton structure: a constituent quark model and the MIT bag model. In the latter case, important differences are found with respect to a previous evaluation in the same framework, a feature already encountered in the calculation of the Sivers function. The results obtained are consistent with the present wisdom, i.e., the contributions for the $u$ and $d$ flavors turn out to have the same sign, following the pattern suggested analyzing the model independent features of the impact parameter dependent generalized parton distributions. It is therefore confirmed that the present approach is suitable for the analysis of time reversal odd distribution functions. A critical comparison between the outcomes of the two models, as well as between the results of the calculations for the Sivers and Boer-Mulders functions, is also carried out.Comment: 26 pages, 5 figures. References added. Final version accepted for publication in Phys. Rev.

CANNABINOID-INDUCED PSYCHOSIS: A CROSS-SECTIONAL GENDER STUDY

Background: Gender is a crucial factor in the development of mental illnesses, with an essential influence on clinical characteristics and not only on the prevalence of each disorder. Gender differences in cannabinoid-related disorders are highlighted by different research fields (preclinical, clinical, socio-demographic studies), but few studies focused on differential symptom expression in cannabinoid-induced psychosis. This study aims at investigating qualitative and quantitative gender differences in specific psychopathological domains in a clinical sample of subjects affected by cannabinoid-induced psychotic disorder, without psychiatric comorbidity. Subjects and methods: The study was carried out at the Psychiatric Inpatient Service of General Hospital of Perugia (Italy). In this cross-sectional gender study, 28 inpatients were enrolled, 14 males (M) and 14 females (F). Participants were administered a psychometric battery consisting of 7 tests (PANSS, NDS-I, YMRS, HAM-D, HAM-A, AQ, SSI) in order to investigate 7 psychopathological domains (Psychosis, Dysphoria, Mania, Depression, Anxiety, Aggressive Behaviour and Suicide Ideation). Scores obtained at each test were compared between male and females by using Mann-Whitney U test (p<0.05). Results: In this study, we observed that males present higher severity of psychotic symptoms, with prominent scores in PANSS positive and general psychopathology scale (p<0.001), and an important expression of aggressive behavior (p<0.001) compared with females. Female sample, instead, shows a greater expression of dysphoria and depressive domains (p<0.001) and a lower, but statistically significant, prevalence in the anxiety domains expression (p=0.01). By these observations, we could assert that in male group thought disorders are prominent. On the other hand, in female group affective disorder are prominent. Conclusions: This study confirmed how gender influences the phenomenic expression of psychiatric disorders. In line with the precision medicine paradigm, a further clarification of different clinical profiles based on gender would allow the choice of a personalized treatment plan with better efficacy and accuracy indices

Universality of nucleon-nucleon short-range correlations: two-nucleon momentum distributions in few-body systems

Using realistic wave functions, the proton-neutron and proton-proton momentum distributions in $^3He$ and $^4He$ are calculated as a function of the relative, $k_{rel}$, and center of mass, $K_{CM}$, momenta, and the angle between them. For large values of ${k}_{rel}\gtrsim 2\,\,fm^{-1}$ and small values of ${K}_{CM} \lesssim 1.0\,\,fm^{-1}$, both distributions are angle independent and decrease with increasing $K_{CM}$, with the $pn$ distribution factorizing into the deuteron momentum distribution times a rapidly decreasing function of $K_{CM}$, in agreement with the two-nucleon (2N) short range correlation (SRC) picture. When $K_{CM}$ and $k_{rel}$ are both large, the distributions exhibit a strong angle dependence, which is evidence of three-nucleon (3N) SRC. The predicted center-of-mass and angular dependence of 2N and 3N SRC should be observable in two-nucleon knock-out processes $A(e,e'pN)X$.Comment: 5 pages, 5 figure