Nuclear response for the Skyrme effective interaction with zero-range tensor terms. II. Sum rules and instabilities

The formalism of linear response theory for Skyrme forces including tensor terms presented in article [1] is generalized for the case of a Skyrme energy density functional in infinite matter. We also present analytical results for the odd-power sum rules, with particular attention to the inverse energy weighted sum rule, $M_{-1}$, as a tool to detect instabilities in Skyrme functionals.Comment: Submitted to Phys. Rev.

Pirate or subscriber? An exploratory study on italian consumers' music habits

Purpose of the paper: This paper analyzes Italian consumers’ music habits in terms of online piracy behaviors and their interest toward subscription-based music services (SBMS), i.e. services that for a small monthly fee give users legal access to vast music libraries across multiple devices. The objective is to try and profile a piracy-prone consumer and explore if SBMS could be a viable alternative to online music piracy in Italy, where the general piracy rate is very high. Methodology: The study is based on an empirical quantitative analysis through the collection of 505 questionnaires completed by Italian consumers. Findings: The paper highlights how Italian consumers reflect the ‘attitude-behavior gap’ in music consumption, as they perceive online music piracy as ethically wrong, yet they still show low preference for the legal, reasonably priced choice (such as SBMS). Younger, male, lower education, students have the highest propensity towards online piracy. In addition, consumers’ awareness, familiarity and interest in subscriptionbased music services are still very low. Research limitations: The limitations of the paper are linked mainly to the adapted scales, to the omission of alternative determinants of attitude towards piracy, to the composition of the sample and for analyzing only two subscription-based music services (Napster and Spotify). Managerial implications: The results call for greater efforts by music industry actors and public institutions to educate Italian consumers about the consequences of their online piracy behavior and the possible solutions offered by SBMS. Originality of the paper: This paper is the first to focus on Italian consumers’ music habits, their attitude and behavior towards online piracy and their interest toward subscription-based music services as a viable alternative

The two-nucleon electromagnetic charge operator in chiral effective field theory (χ\chiEFT) up to one loop

The electromagnetic charge operator in a two-nucleon system is derived in chiral effective field theory ($\chi$EFT) up to order $e\, Q$ (or N4LO), where $Q$ denotes the low-momentum scale and $e$ is the electric charge. The specific form of the N3LO and N4LO corrections from, respectively, one-pion-exchange and two-pion-exchange depends on the off-the-energy-shell prescriptions adopted for the non-static terms in the corresponding potentials. We show that different prescriptions lead to unitarily equivalent potentials and accompanying charge operators. Thus, provided a consistent set is adopted, predictions for physical observables will remain unaffected by the non-uniqueness associated with these off-the-energy-shell effects.Comment: 16 pages, 10 figure

Electromagnetic Structure and Reactions of Few-Nucleon Systems in χ\chiEFT

We summarize our recent work dealing with the construction of the nucleon-nucleon potential and associated electromagnetic currents up to one loop in chiral effective field theory ($\chi$EFT). The magnetic dipole operators derived from these currents are then used in hybrid calculations of static properties and low-energy radiative capture processes in few-body nuclei. A preliminary set of results are presented for the magnetic moments of the deuteron and trinucleons and thermal neutron captures on $p$, $d$, and $^3$He.Comment: Invited talk to the 19th International IUPAP Conference on Few-Body Problems in Physic

Electromagnetic structure of A=2 and 3 nuclei in chiral effective field theory

The objectives of the present work are twofold. The first is to address and resolve some of the differences present in independent, chiral-effective-field-theory (\chiEFT) derivations up to one loop, recently appeared in the literature, of the nuclear charge and current operators. The second objective is to provide a complete set of \chiEFT predictions for the structure functions and tensor polarization of the deuteron, for the charge and magnetic form factors of 3He and 3H, and for the charge and magnetic radii of these few-nucleon systems. The calculations use wave functions derived from high-order chiral two- and three-nucleon potentials and Monte Carlo methods to evaluate the relevant matrix elements. Predictions based on conventional potentials in combination with \chiEFT charge and current operators are also presented. There is excellent agreement between theory and experiment for all these observables for momentum transfers up to q< 2.0-2.5 (1/fm); for a subset of them, this agreement extends to momentum transfers as high as q~5-6 (1/fm). A complete analysis of the results is provided.Comment: 34 pages, Revte

Parental involvement in the lives of intercollegiate athletes

Research has been growing on the topic of parental involvement in the lives of their children, and the concept of overinvolved parents. Little research has examined these topics in regards to intercollegiate student-athletes. This study addresses that gap by examining parental involvement in regards to intercollegiate student-athletes and their athletic and academic endeavors. Specifically it examines how involved parents are in the lives of their intercollegiate student-athlete children, and the concept of overinvolvement in regards to this population. A qualitative, case-study method was utilized for this research. Participants included eight intercollegiate student-athletes and the five academic advisors for athletics that worked with them. Participants completed two interviews and one journal, and all of the data was analyzed utilizing thematic analysis. The themes that emerged were types of involvement, increasing involvement, overinvolvement, outcomes of overinvolvement, and the fine line between healthy involvement and overinvolvement. The present study offers insight into how student-athletes and academic advisors perceive parental involvement. This knowledge can be utilized by practitioners to improve how they communicate with parents and student-athletes. Also, researchers can employ this information to improve the overall understanding of parental involvement in regards to athletes.

Electromagnetic processes in a χ\chiEFT framework

Recently, we have derived a two--nucleon potential and consistent nuclear electromagnetic currents in chiral effective field theory with pions and nucleons as explicit degrees of freedom. The calculation of the currents has been carried out to include N$^3$LO corrections, consisting of two--pion exchange and contact contributions. The latter involve unknown low-energy constants (LECs), some of which have been fixed by fitting the $np$ S- and P-wave phase shifts up to 100 MeV lab energies. The remaining LECs entering the current operator are determined so as to reproduce the experimental deuteron and trinucleon magnetic moments, as well as the $np$ cross section. This electromagnetic current operator is utilized to study the $nd$ and $n^3$He radiative captures at thermal neutron energies. Here we discuss our results stressing on the important role played by the LECs in reproducing the experimental data.Comment: Invited talk at the 5th International Conference on Quarks and Nuclear Physics, to appear in Chinese Physics

Thermal neutron captures on dd and 3^3He

We report on a study of the $nd$ and $n\,^3$He radiative captures at thermal neutron energies, using wave functions obtained from either chiral or conventional two- and three-nucleon realistic potentials with the hyperspherical harmonics method, and electromagnetic currents derived in chiral effective field theory up to one loop. The predicted $nd$ and $n\,^3$He cross sections are in good agreement with data, but exhibit a significant dependence on the input Hamiltonian. A comparison is also made between these and new results for the $nd$ and $n\,^3$He cross sections obtained in the conventional framework for both potentials and currents.Comment: 4 pages, 4 eps figures; references added; corrections to text and abstract as suggested by referee adde

Jamming in complex networks with degree correlation

We study the effects of the degree-degree correlations on the pressure congestion J when we apply a dynamical process on scale free complex networks using the gradient network approach. We find that the pressure congestion for disassortative (assortative) networks is lower (bigger) than the one for uncorrelated networks which allow us to affirm that disassortative networks enhance transport through them. This result agree with the fact that many real world transportation networks naturally evolve to this kind of correlation. We explain our results showing that for the disassortative case the clusters in the gradient network turn out to be as much elongated as possible, reducing the pressure congestion J and observing the opposite behavior for the assortative case. Finally we apply our model to real world networks, and the results agree with our theoretical model