1,513 research outputs found

    The Long Journey from Ab Initio Calculations to Density Functional Theory for Nuclear Large Amplitude Collective Motion

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    At present there are two vastly different ab initio approaches to the description of the the many-body dynamics: the Density Functional Theory (DFT) and the functional integral (path integral) approaches. On one hand, if implemented exactly, the DFT approach can allow in principle the exact evaluation of arbitrary one-body observable. However, when applied to Large Amplitude Collective Motion (LACM) this approach needs to be extended in order to accommodate the phenomenon of surface-hoping, when adiabaticity is strongly violated and the description of a system using a single (generalized) Slater determinant is not valid anymore. The functional integral approach on the other hand does not appear to have such restrictions, but its implementation does not appear to be straightforward endeavor. However, within a functional integral approach one seems to be able to evaluate in principle any kind of observables, such as the fragment mass and energy distributions in nuclear fission. These two radically approaches can likely be brought brought together by formulating a stochastic time-dependent DFT approach to many-body dynamics.Comment: 9 page

    Self-consistent quantal treatment of decay rates within the perturbed static path approximation

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    The framework of the Perturbed Static Path Approximation (PSPA) is used to calculate the partition function of a finite Fermi system from a Hamiltonian with a separable two body interaction. Therein, the collective degree of freedom is introduced in self-consistent fashion through a Hubbard-Stratonovich transformation. In this way all transport coefficients which dominate the decay of a meta-stable system are defined and calculated microscopically. Otherwise the same formalism is applied as in the Caldeira-Leggett model to deduce the decay rate from the free energy above the so called crossover temperature T0T_0.Comment: 17 pages, LaTex, no figures; final version, accepted for publication in PRE; e-mail: [email protected]

    First results from the NA60 experiment at CERN

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    Since 1986, several heavy ion experiments have studied some signatures of the formation of the quark-gluon plasma and a few exciting results have been found. However, some important questions are still unanswered and require new measurements. The NA60 experiment, with a new detector concept that vastly improves dimuon detection in proton-nucleus and heavy-ion collisions, studies several of those open questions, including the production of open charm. This paper presents the experiment and some first results from data collected in 2002.Comment: Paper presented at the XXXVIII Rencontres de Moriond, QCD and High Energy Hadronic Interactions, Les Arcs, March 22-29, 2003. 4 pages, 6 figure

    Ď•\phi Meson Production in In-In Collisions and the Ď•\phi Puzzle

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    The NA60 experiment measured dimuon production in In-In collisions at 158 AGeV. This paper presents a high statistics measurement of ϕ→μμ\phi\to\mu\mu with the specific objective to provide insight on the ϕ\phi puzzle, i.e. the difference in the inverse TT slopes and absolute yields measured by NA49 and NA50 in the kaon and lepton channel, respectively. Transverse momentum distributions were studied as a function of centrality. The slope parameter TT shows a rapid increase with centrality, followed by a saturation. Variations of TT with the fit range of the order of 15 MeV were observed, possibly as a consequence of radial flow. The ϕ\phi meson yield normalized to the number of participants increases with centrality and is consistently higher than the yield measured by the NA49 experiment at any centrality.Comment: 4 Pages, 2 Figures. Proceedings of the 20th^{th} International Conference on Ultra-Relativistic Nucleus Nucleus Collision

    Thermal dileptons at SPS energies

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    Clear signs of excess dileptons above the known sources were found at the SPS since long. However, a real clarification of these observations was only recently achieved by NA60, measuring dimuons with unprecedented precision in 158A GeV, In-In collisions. The excess mass spectrum in the region M<1 GeV is consistent with a dominant contribution from pi+pi- -> rho -> mu+mu- annihilation. The associated rho spectral function shows a strong broadening, but essentially no shift in mass. In the region M>1 GeV, the excess is found to be prompt, not due to enhanced charm production. The inverse slope parameter Teff associated with the transverse momentum spectra rises with mass up to the rho, followed by a sudden decline above. While the initial rise, coupled to a hierarchy in hadron freeze-out, points to radial flow of a hadronic decay source, the decline above signals a transition to a low-flow source, presumably of partonic origin. The mass spectra show at low transverse momenta the steep rise towards low masses characteristic for Planck-like radiation. The polarization of the excess referred to the Collins Soper frame is found to be isotropic. All observations are consistent with the interpretation of the excess as thermal radiation.Comment: Prepared for 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions: Quark Matter 2008 (QM2008), Jaipur, India, 4-10 Feb. 200

    Gender differences in asthma perception and its impact on quality of life: A post hoc analysis of the PROXIMA (Patient Reported Outcomes and Xolair\uae in the Management of Asthma) study

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    Background: Gender differences in asthma perception and control have been reported. The PROXIMA observational study assessed these outcomes in a cohort of Italian severe allergic asthma (SAA) patients. This post hoc analysis of the PROXIMA results was aimed at assessing gender differences in SAA in a real-world setting, focusing on disease perception and impact on quality of life (QoL). Methods: The PROXIMA study was an observational, multicenter study, consisting of a cross-sectional and a prospective longitudinal phase, including adult outpatients diagnosed with SAA at step 4 requiring a therapeutic step-up. Patients on omalizumab treatment at baseline were included in the 12-month longitudinal phase. Disease control was assessed by the Asthma Control Questionnaire (ACQ) score, patients' disease perception by the Brief Illness Perception Questionnaire (BIPQ), and QoL by the EuroQoL five-dimensional three-level questionnaire (EQ-5D-3 L) at baseline and after 6 and 12 months. Two regression models were used to evaluate the association between gender and BIPQ total score and EQ-5D-3L score, respectively. Results: 357 patients (65% females) were analyzed for the cross-sectional phase and 99 (62.6% females) for the longitudinal phase. The prevalence of perennial and seasonal aeroallergens was similar between genders. ACQ score decreased similarly during omalizumab treatment at 6 and 12 months in both genders; no gender differences were observed in control rates. Asthma perception was worse among females at all study visits reaching statistical significance at 12 months (mean (SD) B-IPQ total score 41.8 (9.4) vs 35.6 (12.0); T test p-value (males vs females) &lt; 0.05). Statistically significant gender differences were observed for some specific items, with males reporting less symptom experience, concern about the disease, and emotional impact at 12-months. The results of the multivariate regression model for repeated measures showed that overall treatment with omalizumab improved disease perception overtime regardless from gender. Males reported a significantly better QoL compared to females at both 6 and 12 months. Conclusions: In this real-world setting, females confirmed to have a worse perception of asthma, feel it as more symptomatic and suffer a greater impact on their QoL, even though having similar baseline severity and obtaining similar level of control

    INFN What Next: Ultra-relativistic Heavy-Ion Collisions

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    This document was prepared by the community that is active in Italy, within INFN (Istituto Nazionale di Fisica Nucleare), in the field of ultra-relativistic heavy-ion collisions. The experimental study of the phase diagram of strongly-interacting matter and of the Quark-Gluon Plasma (QGP) deconfined state will proceed, in the next 10-15 years, along two directions: the high-energy regime at RHIC and at the LHC, and the low-energy regime at FAIR, NICA, SPS and RHIC. The Italian community is strongly involved in the present and future programme of the ALICE experiment, the upgrade of which will open, in the 2020s, a new phase of high-precision characterisation of the QGP properties at the LHC. As a complement of this main activity, there is a growing interest in a possible future experiment at the SPS, which would target the search for the onset of deconfinement using dimuon measurements. On a longer timescale, the community looks with interest at the ongoing studies and discussions on a possible fixed-target programme using the LHC ion beams and on the Future Circular Collider.Comment: 99 pages, 56 figure

    First results from NA60 on low mass muon pair production in In-In collisions at 158 GeV/nucleon

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    The NA60 experiment at the CERN SPS studies dimuon production in proton-nucleus and nucleus-nucleus collisions. The combined information from a novel vertex telescope made of radiation-tolerant silicon pixel detectors and from the muon spectrometer previously used in NA50 allows for a precise measurement of the muon vertex and a much improved dimuon mass resolution. We report on first results from the data taken for Indium-Indium collisions at 158 AGeV/nucleon in 2003, concentrating on a subsample of about 370 000 muon pairs in the mass range <1.2<1.2 GeV/c2c^{2}. The light vector mesons ω\omega and ϕ\phi are completely resolved, with a mass resolution of about 23 MeV/c2c^{2} at the ϕ\phi. The transverse momentum spectra of the ϕ\phi are measured over the continuous range 0<pT<2.50<p_{\rm T}<2.5 GeV/c; the inverse slope parameter of the spectra is found to increase with centrality, with an average value of T=252±3T=252\pm3 MeV.Comment: 9 pages, 6 figures. Plenary talk, SQM2004 conference, Cape Town, South Africa 15-20 September, 2004. To be published in Journal of Physics G: Nuclear and Particle Physic

    NA60 results on thermal dimuons

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    The NA60 experiment at the CERN SPS has measured muon pairs with unprecedented precision in 158A GeV In-In collisions. A strong excess of pairs above the known sources is observed in the whole mass region 0.2<M<2.6 GeV. The mass spectrum for M<1 GeV is consistent with a dominant contribution from pi+pi- -> rho -> mu+mu- annihilation. The associated rho spectral function shows a strong broadening, but essentially no shift in mass. For M>1 GeV, the excess is found to be prompt, not due to enhanced charm production, with pronounced differences to Drell-Yan pairs. The slope parameter Teff associated with the transverse momentum spectra rises with mass up to the rho, followed by a sudden decline above. The rise for M<1 GeV is consistent with radial flow of a hadronic emission source. The seeming absence of significant flow for M>1 GeV and its relation to parton-hadron duality is discussed in detail, suggesting a dominantly partonic emission source in this region. A comparison of the data to the present status of theoretical modeling is also contained. The accumulated empirical evidence, including also a Planck-like shape of the mass spectra at low pT and the lack of polarization, is consistent with a global interpretation of the excess dimuons as thermal radiation. We conclude with first results on omega in-medium effects.Comment: 10 pages, 12 figures, submitted to Eur. Phys. J.

    Notulae to the Italian flora of algae, bryophytes, fungi and lichens: 4

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    In this contribution, new data concerning bryophytes, fungi and lichens of the Italian flora are presented. It includes new records and confirmations for the bryophyte genera Campylopus, Paludella, Tortula, and Conocephalum, the fungal genera Agonimia, Buelliella, Entorrhiza, Filicupula, Poronia, and Sporisorium, the lichen genera Cladonia, Dibaeis, Lasallia, and Rhizocarpon
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