Complesso University Monte gelo

Napoli, Italy

Complesso University Monte gelo

Napoli, Italy
Time filter
Source Type

Chianese M.,Complesso University Monte gelo | Chianese M.,University of Naples Federico II | Chianese M.,Max Planck Institute for Physics | Merle A.,Max Planck Institute for Physics
Journal of Cosmology and Astroparticle Physics | Year: 2017

The high energy events observed at the IceCube Neutrino Observatory have triggered many investigations interpreting the highly energetic neutrinos detected as decay products of heavy unstable Dark Matter particles. However, while very detailed treatments of the IceCube phenomenology exist, only a few references focus on the (non-trivial) Dark Matter production part - and all of those rely on relatively complicated new models which are not always testable directly. We instead investigate two of the most minimal scenarios possible, where the operator responsible for the IceCube events is directly involved in Dark Matter production. We show that the simplest (four-dimensional) operator is not powerful enough to accommodate all constraints. A more non-minimal setting (at mass dimension six), however, can do both fitting all the data and also allowing for a comparatively small parameter space only, parts of which can be in reach of future observations. We conclude that minimalistic approaches can be enough to explain all data required, while complicated new physics seems not to be required by IceCube. © 2017 IOP Publishing Ltd and Sissa Medialab srl .

Chianese M.,University of Naples Federico II | Chianese M.,Complesso University Monte gelo
Journal of Physics: Conference Series | Year: 2016

We analyze the scenario where the IceCube high energy neutrino events are explained in terms of an extraterrestrial flux due to two different components: a contribution coming from know astrophysical sources for energies up to few hundreds TeV and a top-down contribution originated by the decay of heavy dark matter particles with a mass of few PeV. Contrary to previous approaches, we consider a leptophilic three-body decay that dominates at PeV energies due to the absence of quarks in the final state. We find that the theoretical predictions of such a scenario are in a slightly better agreement with the IceCube data if the astrophysical component has a cut-off at about 100 TeV. This interpretation of IceCube data can be easily tested in the near future since the decaying dark matter scenario predicts a sharp cut-off at PeV energy scale and the observation of an anisotropy towards Galactic Center of our Galaxy in contrast with the isotropic astrophysical flux. © Published under licence by IOP Publishing Ltd.

Biczysko M.,Normal School of Pisa | Biczysko M.,Complesso University Monte gelo | Panek P.,Complesso University Monte gelo | Panek P.,Wrocław University | And 5 more authors.
Journal of Chemical Theory and Computation | Year: 2010

This work aims to provide reliable benchmark data on the accuracy of harmonic and anharmonic vibrational frequencies computed with the B2PLYP double-hybrid density functional method. The exchange-correlation contributions required for the B2PLYP analytical second derivatives are presented here, which allow for the effective calculation of harmonic frequency as well as cubic and semidiagonal quartic force fields. The latter, in turn, are necessary to compute the anharmonic vibrational frequencies with the perturbative approach (VPT2). The quality of harmonic vibrational frequencies computed in conjunction with basis sets of double- to quadruple-ζ quality has been checked against reference data from the F38 benchmark set. Then, for an additional set of small closed- and open-shell systems, both harmonic frequencies and anharmonic contributions computed at the B2PLYP/N07D and the B2PLYP/aug-cc-pVTZ levels have been compared to their CCSD(T) counterparts. Moreover, for selected medium-size molecules (furan, pyrrole, thiophene, uracil, anisole, phenol, and pyridine), anharmonic frequencies have been compared to well established experimental results. Such benchmark studies have shown that the B2PLYP/N07D model provides good quality harmonic frequencies and describes correctly anharmonic contributions, the latter being of similar accuracy to their B3LYP/N07D counterparts, but obtained at significantly larger computational cost. Additionally, increased accuracy can be obtained by adopting hybrid models where the B2PLYP/N07D anharmonic contributions are combined with harmonic frequencies computed with more accurate quantum mechanical (QM) approaches or by B2PLYP with larger basis sets. This work confirmed also that most of the recently developed density functionals are significantly less suited for vibrational computations, while the B2PLYP method can be recommended for spectroscopic studies where a good accuracy of vibrational properties is required. © 2010 American Chemical Society.

Marcucci L.E.,University of Pisa | Marcucci L.E.,National Institute of Nuclear Physics, Italy | Mangano G.,Complesso University Monte gelo | Kievsky A.,National Institute of Nuclear Physics, Italy | Viviani M.,National Institute of Nuclear Physics, Italy
Physical Review Letters | Year: 2016

The astrophysical S factor for the radiative capture d(p,γ)He3 in the energy range of interest for big bang nucleosynthesis (BBN) is calculated using an ab initio approach. The nuclear Hamiltonian retains both two- and three-nucleon interactions - the Argonne v18 and the Urbana IX, respectively. Both one- and many-body contributions to the nuclear current operator are included. The former retain for the first time, besides the 1/m leading order contribution (m is the nucleon mass), also the next-to-leading order term, proportional to 1/m3. The many-body currents are constructed in order to satisfy the current conservation relation with the adopted Hamiltonian model. The hyperspherical harmonics technique is applied to solve the A=3 bound and scattering states. Particular attention is paid in this second case in order to obtain, in the energy range of BBN, an uncertainty on the astrophysical S factor of the order or below ∼1%. Then, in this energy range, the S factor is found to be ∼10% larger than the currently adopted values. Part of this increase (1%-3%) is due to the 1/m3 one-body operator, while the remaining is due to the new more accurate scattering wave functions. We have studied the implication of this new determination for the d(p,γ)He3 S factor on the deuterium primordial abundance. We find that the predicted theoretical value for H2/H is in excellent agreement with its experimental determination, using the most recent determination of the baryon density of the Planck experiment, and with a standard number of relativistic degrees of freedom Neff=3.046 during primordial nucleosynthesis. This calls for a more accurate measurement of the astrophysical S factor in order to confirm the present predictions. © 2016 American Physical Society.

Mangano G.,LAPTh | Mangano G.,Complesso University Monte gelo | Serpico P.D.,LAPTh
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We derive here a robust bound on the effective number of neutrinos from constraints on primordial nucleosynthesis yields of deuterium and helium. In particular, our results are based on very weak assumptions on the astrophysical determination of the helium abundance, namely that the minimum effect of stellar processing is to keep constant (rather than increase, as expected) the helium content of a low-metallicity gas. Using the results of a recent analysis of extragalactic HII regions as upper limit, we find that δNeff≤1 at 95% C.L., quite independently of measurements on the baryon density from cosmic microwave background anisotropy data and of the neutron lifetime input. In our approach, we also find that primordial nucleosynthesis alone has no significant preference for an effective number of neutrinos larger than the standard value. The ~2σ hint sometimes reported in the literature is thus driven by CMB data alone and/or is the result of a questionable regression protocol to infer a measurement of primordial helium abundance. © 2011 Elsevier B.V.

Horvath Z.,University of Szeged | Gergely L.A.,University of Szeged | Hobill D.,University of Calgary | Capozziello S.,University of Naples Federico II | And 2 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We discuss weak lensing characteristics in the gravitational field of a compact object in the low-energy approximation of fourth order f(R)-gravity theory. The particular solution is characterized by a gravitational strength parameter σ and a distance scale rc much larger than the Schwarzschild radius. Above rc gravity is strengthened and as a consequence weak lensing features are modified compared to the Schwarzschild case. We find a critical impact parameter (depending upon rc) for which the behavior of the deflection angle changes. Using the Virbhadra-Ellis lens equation we improve the computation of the image positions, Einstein ring radii, magnification factors and the magnification ratio. We demonstrate that the magnification ratio as function of image separation obeys a power law depending on the parameter σ, with a double degeneracy. No σ≠0 value gives the same power as the one characterizing Schwarzschild black holes. As the magnification ratio and the image separation are the lensing quantities most conveniently determined by direct measurements, future lensing surveys will be able to constrain the parameter σ based on this prediction. © 2013 American Physical Society.

Chianese M.,Complesso University Monte gelo | Chianese M.,University of Naples Federico II | Miele G.,Complesso University Monte gelo | Miele G.,University of Naples Federico II | And 4 more authors.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

In this Letter we focus our attention on the IceCube events in the energy range between 60 and 100 TeV, which show an order 2-sigma excess with respect to a power-law with spectral index 2. We analyze the possible origin of such an excess by comparing the distribution of the arrival directions of IceCube events with the angular distributions of simply distributed astrophysical galactic/extragalactic sources, as well as with the expected flux coming from DM interactions (decay and annihilation) for different DM profiles. The statistical analysis performed seems to disfavor the correlation with the galactic plane, whereas rules out the DM annihilation scenario only in case of small clumpiness effect. The small statistics till now collected does not allow to scrutinize the cases of astrophysical isotropic distribution and DM decay scenarios. For this reason we perform a forecast analysis in order to stress the role of future Neutrino Telescopes. © 2016 The Authors.

Cotroneo D.,University of Naples Federico II | Cotroneo D.,Complesso University Monte gelo | Di Leo D.,University of Naples Federico II | Di Leo D.,Complesso University Monte gelo | And 3 more authors.
2013 28th IEEE/ACM International Conference on Automated Software Engineering, ASE 2013 - Proceedings | Year: 2013

The assessment of operating systems robustness with respect to unexpected or anomalous events is a fundamental requirement for mission-critical systems. Robustness can be tested by deliberately exposing the system to erroneous events during its execution, and then analyzing the OS behavior to evaluate its ability to gracefully handle these events. Since OSs are complex and stateful systems, robustness testing needs to account for the timing of erroneous events, in order to evaluate the robust behavior of the OS under different states. This paper presents SABRINE (StAte-Based Robustness testIng of operatiNg systEms), an approach for state-aware robustness testing of OSs. SABRINE automatically extracts state models from execution traces, and generates a set of test cases that cover different OS states. We evaluate the approach on a Linux-based Real-Time Operating System adopted in the avionic domain. Experimental results show that SABRINE can automatically identify relevant OS states, and find robustness vulnerabilities while keeping low the number of test cases. © 2013 IEEE.

Dargiewicz M.,Complesso University Monte gelo | Biczysko M.,Complesso University Monte gelo | Biczysko M.,Italian Institute of Technology | Improta R.,CNR Institute of Biostructure and Bioimaging | Barone V.,Normal School of Pisa
Physical Chemistry Chemical Physics | Year: 2012

Time-Dependent Density Functional Theory (TD-DFT) computations, with M05-2X and PBE0 functionals, have been employed for a detailed study of the Electron-Driven Proton-Transfer (PT) processes in an Adenine-Thymine Watson-Crick Base Pair in the gas phase and in solution, with the bulk solvent described by the polarizable continuum model. In the gas phase, TD-DFT computations predict that the Adenine → Thymine Charge Transfer (CT) excited state undergoes a barrierless PT reaction, in agreement with CC2 computations (S. Perun, A. Sobolewski, W. Domcke, J. Phys. Chem. A, 2006, 110, 9031.). The good agreement between the TD-DFT approach and CC2 results validates the former for the studies of excited state properties, excited state proton transfer reaction, and deactivation mechanisms in the DNA base pairs. Next, it is shown that inclusion of solvent effects significantly influences the possibility of both barrier-less excited state proton transfer and radiation-less deactivation through conical intersection with the ground state, affecting the energy of the CT excited state in the Franck-Condon region, the energy barrier associated to the PT process and the energy gap with the ground electronic state. These findings clearly indicate that environmental effects, with a special attention to proper treatment of dynamical solvation effects, have to be included for reliable computational analysis of photophysical and photochemical processes occurring in condensed phases. © 2012 the Owner Societies.

Barone V.,Normal School of Pisa | Bloino J.,Normal School of Pisa | Bloino J.,Complesso University Monte gelo | Biczysko M.,Complesso University Monte gelo
Physical Chemistry Chemical Physics | Year: 2010

The DFT/N07D computational model has been applied to the study of molecular structure, vibrational frequencies and hyperfine coupling constants of vinyl radical in the ground electronic state, taking into account vibrational effects beyond harmonic approximation. Moreover, the TD-DFT/N07D approach has been applied to the study of structures and properties of the title radical in excited electronic states. Vertical and adiabatic electronic excitation energies have been computed and the vibrationally resolved one photon absorption spectrum of the Ã2A′′←X2A 1 electronic transition has been simulated. Computational results have been compared with the available experimental data and theoretical studies at the coupled-cluster and MRCI levels, showing remarkable accuracy of the TD-DFT/DFT//N07D model. This finding paves the route toward reliable studies of magnetic, vibrational and electronic properties for quite large unstable open-shell species of current biological and/or technological interest in their ground and excited electronic states. © 2010 the Owner Societies.

Loading Complesso University Monte gelo collaborators
Loading Complesso University Monte gelo collaborators