Constraining relativistic models through heavy ion collisions

Relativistic models can be successfully applied to the description of compact star properties in nuclear astrophysics as well as to nuclear matter and finite nuclei properties, these studies taking place at low and moderate temperatures. Nevertheless, all results are model dependent and so far it is unclear whether some of them should be discarded. Moreover, in the regime of hot hadronic matter very few calculations exist using these relativistic models, in particular when applied to particle yields in heavy ion collisions. In the present work we comment on the known constraints that can help the selection of adequate models in this regime and investigate the main differences that arise when the particle production during a Au+Au collision at RHIC is calculated with different models.Comment: 9 pages, 1 figure, 3 table

Kaons production at finite temperature and baryon density in an effective relativistic mean field model

We investigate the kaons production at finite temperature and baryon density by means of an effective relativistic mean-field model with the inclusion of the full octet of baryons. Kaons are considered taking into account of an effective chemical potential depending on the self-consistent interaction between baryons. The obtained results are compared with a minimal coupling scheme, calculated for different values of the anti-kaon optical potential.Comment: 3 pages, contribution presented to the International Conference on Exotic Atoms and Related Topic

Early, incomplete, or preclinical autoimmune systemic rheumatic diseases and pregnancy outcome

OBJECTIVE: To evaluate the impact of preclinical systemic autoimmune rheumatic disorders on pregnancy outcome. METHODS: In this longitudinal cohort study, patients were enrolled during the first trimester of pregnancy if they reported having had connective tissue disorder symptoms, were found to be positive for circulating autoantibodies, and on clinical evaluation were judged to have a preclinical or incomplete rheumatic disorder. The incidence of fetal growth restriction (FGR), preeclampsia, and adverse pregnancy outcomes in patients with preclinical rheumatic disorders was compared with that in selected controls, after adjustment for confounders by penalized logistic regression. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated. RESULTS: Of 5,232 women screened, 150 (2.9%) were initially diagnosed as having a suspected rheumatic disorder. After a mean\u2009\ub1\u2009SD postpartum follow-up of 16.7\u2009\ub1\u20095.5 months, 64 of these women (42.7%) had no clinically apparent rheumatic disease and 86 (57.3%) had persistent symptoms and positive autoantibody results, including 10 (6.7%) who developed a definitive rheumatic disease. The incidences of preeclampsia/FGR and of small for gestational age (SGA) infants were 5.1% (23 of 450) and 9.3% (42 of 450), respectively, among controls, 12.5% (8 of 640) (OR 2.7 [95% CI 1.1-6.4]) and 18.8% (12 of 64) (OR 2.2 [95% CI 1.1-4.5]), respectively, among women with no clinically apparent disease, and 16.3% (14 of 86) (OR 3.8 [95% CI 1.9-7.7]) and 18.6% (16 of 86) (OR 2.3 [95% CI 1.2-4.3]), respectively, among those with persisting symptoms at follow-up. Mean\u2009\ub1\u2009SD umbilical artery Doppler pulsatility indices were higher among women with no clinically apparent disease (0.95\u2009\ub1\u20090.2) and those with persisting symptoms (0.96\u2009\ub1\u20090.21) than in controls (0.89\u2009\ub1\u20090.12) (P\u2009=\u20090.01 and P\u2009<\u20090.001, respectively). CONCLUSION: In our study population, preclinical rheumatic disorders were associated with an increased risk of FGR/preeclampsia and SGA. The impact of these findings and their utility in screening for FGR/preeclampsia need to be confirmed in population studies

The importance of the mixed phase in hybrid stars built with the Nambu-Jona-Lasinio model

We investigate the structure of hybrid stars based on two different constructions: one is based on the Gibbs condition for phase coexistence and considers the existence of a mixed phase (MP), and the other is based on the Maxwell construction and no mixed phase is obtained. The hadron phase is described by the non-linear Walecka model (NLW) and the quark phase by the Nambu-Jona-Lasinio model (NJL). We conclude that the masses and radii obtained are model dependent but not significantly different for both constructions.Comment: 8 pages, 7 figures, 3 table

Non-gaussian statistics and the relativistic nuclear equation of state

We investigate possible effects of quantum power-law statistical mechanics on the relativistic nuclear equation of state in the context of the Walecka quantum hadrodynamics theory. By considering the Kaniadakis non-Gaussian statistics, characterized by the index $\kappa$ (Boltzmann-Gibbs entropy is recovered in the limit $\kappa\to 0$), we show that the scalar and vector meson fields become more intense due to the non-Gaussian statistical effects ($\kappa \neq 0$). From an analytical treatment, an upper bound on $\kappa$ ($\kappa < 1/4$) is found. We also show that as the parameter $\kappa$ increases the nucleon effective mass diminishes and the equation of state becomes stiffer. A possible connection between phase transitions in nuclear matter and the $\kappa$-parameter is largely discussed.Comment: 8 pages, 8 fifures, LaTe

Irradiation Tests of the Pixel Front-End Readout Electronics for the ALICE Experiment at LHC

The problem of radiation damage for the electronics of the pixel detectors in the Inner Tracking System of the ALICE experiment is discussed. Simulations allowed to estimate the cumulated doses andparticle fluences during a ten year operational period. Several irradiation tests have been carried out on the various prototypes of the readout chips. The results obtained so far point out that the recent prototypes will retain their functionality up to doses and neutron fluences well above those expected in ALICE