We develop an innovative technique for studying inhomogeneous phases with a spontaneous broken symmetry. The method relies on the knowledge of the exact form of the free energy in the homogeneous ...phase and on a specific gradient expansion of the order parameter. We apply this method to quark matter at vanishing temperature and large chemical potential, which is expected to be relevant for astrophysical considerations. The method is remarkably reliable and fast as compared to performing the full numerical diagonalization of the quark Hamiltonian in momentum space and is designed to improve the standard Ginzburg-Landau expansion close to the phase transition points. For definiteness, we focus on inhomogeneous chiral symmetry breaking, accurately reproducing known results for one-dimensional and two-dimensional modulations and examining novel crystalline structures, as well. Consistently with previous results, we find that the energetically favored modulation is the so-called one-dimensional real-kink crystal. We propose a qualitative description of the pairing mechanism to motivate this result.
To be able to achieve their physics goals, future neutrino-oscillation experiments will need to reconstruct the neutrino energy with very high accuracy. In this work, we analyze how the energy ...reconstruction may be affected by realistic detection capabilities, such as energy resolutions, efficiencies, and thresholds. This allows us to estimate how well the detector performance needs to be determined a priori in order to avoid a sizable bias in the measurement of the relevant oscillation parameters. We compare the kinematic and calorimetric methods of energy reconstruction in the context of two νμ → νμ disappearance experiments operating in different energy regimes. For the calorimetric reconstruction method, we find that the detector performance has to be estimated with an O(10%) accuracy to avoid a significant bias in the extracted oscillation parameters. Thus, in the case of kinematic energy reconstruction, we observe that the results exhibit less sensitivity to an overestimation of the detector capabilities.
The model of Nambu and Jona-Lasinio has been extensively used to model the possible occurrence of quark matter in the core of compact stars. While based entirely on similar physical assumptions, ...previous studies have been performed using a variety of model versions, differing in both the number of active quark flavors and the structure of the quark-quark interaction. We discuss the results of our systematic analysis, designed to clarify the role of the vector and instanton-induced interactions in determining the properties of hybrid stars. The results of our calculations, carried out using a state-of-the-art description of the hadronic phase, show that the instanton-induced interaction does not affect the stiffness of the quark matter equation of state, whereas the effect of the repulsive vector interaction is sizable. However, no values of the corresponding coupling constants allow for the formation of a stable core of quark matter.
We discuss the dependence of the pulsation frequencies of the axial quasi-normal modes of a non-rotating neutron star upon the equation of state describing the star interior. The continued fraction ...method has been used to compute the complex frequencies for a set of equations of state based on different physical assumptions and spanning a wide range of stiffness. The numerical results show that axial gravitational waves carry relevant information on both the structure of neutron star matter and the nature of the hadronic interactions.
Proton decay and nuclear dynamics Alvioli, M.; Benhar, O.; Ericson, M. ...
Physical review. C, Nuclear physics,
04/2010, Letnik:
81, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The kinematics of the decay of a bound proton is governed by the proton spectral function. We evaluate this quantity in {sup 16}O using the information from nuclear physics experiments. It also ...includes a correlated part. The reliability of this evaluation is sufficient to open the possibility of correlated cuts in the missing mass and momentum variables to identify the decay events from the bound protons with a possible increase of the signal-to-noise ratio.
The transition from hadronic matter to quark matter in the core of neutron stars is likely to be associated with the appearance of a mixed phase, leading to a smooth variation of the star density ...profile. We discuss the results of a systematic study of the properties of the mixed phase on Coulomb and surface effects. A state-of-the-art nonrelativistic equation of state of nuclear matter has been used for the low density phase, while quark matter has been described within the MIT bag model, including the effect of perturbative one-gluon exchange interactions. The implications for neutron star structure are discussed.
Precise measurement of neutrino oscillations, and hence the determination of their masses demands a quantitative understanding of neutrino-nucleus interactions. To this aim, two-body meson-exchange ...currents have to be accounted for along within realistic models of nuclear dynamics. We summarize our progresses towards the construction of a consistent framework, based on quantum Monte Carlo methods and on the spectral function approach, that can be exploited to accurately describe neutrino interactions with atomic nuclei over the broad kinematical region covered by neutrino experiments.
We report the results of a calculation of the neutrino- and antineutrino-induced γ-ray production cross section for oxygen target. Our analysis is focused on the kinematical region of neutrino energy ...larger than ~200 MeV, in which single-nucleon knockout is known to be the dominant reaction mechanism. The numerical results have been obtained using a realistic model of the target spectral function, extensively tested against electron-nucleus scattering data. We find that at neutrino energy 600 MeV the fraction of neutral-current interactions leading to emission of γ-rays of energy larger than 6 MeV is ~41%, and that the contribution of the p3/2 state is overwhelming.
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