7,887 research outputs found
Relativistic Hamiltonians in many-body theories
We discuss the description of a many-body nuclear system using Hamiltonians
that contain the nucleon relativistic kinetic energy and potentials with
relativistic corrections. Through the Foldy-Wouthuysen transformation, the
field theoretical problem of interacting nucleons and mesons is mapped to an
equivalent one in terms of relativistic potentials, which are then expanded at
some order in 1/m_N. The formalism is applied to the Hartree problem in nuclear
matter, showing how the results of the relativistic mean field theory can be
recovered over a wide range of densities.Comment: 14 pages, uses REVTeX and epsfig, 3 postscript figures; a postscript
version of the paper is available by anonymous ftp at
ftp://carmen.to.infn.it/pub/depace/papers/951
Fermion propagators in space-time
The one- and the two-particle propagators for an infinite non-interacting
Fermi system are studied as functions of space-time coordinates. Their
behaviour at the origin and in the asymptotic region is discussed, as is their
scaling in the Fermi momentum. Both propagators are shown to have a divergence
at equal times. The impact of the interaction among the fermions on their
momentum distribution, on their pair correlation function and, hence, on the
Coulomb sum rule is explored using a phenomenological model. Finally the
problem of how the confinement is reflected in the momentum distribution of the
system's constituents is briefly addressed.Comment: 26 pages, 9 figures, accepted for publication on Phys. Rev.
Inelastic electron-nucleus scattering and scaling at high inelasticity
Highly inelastic electron scattering is analyzed within the context of the
unified relativistic approach previously considered in the case of quasielastic
kinematics. Inelastic relativistic Fermi gas modeling that includes the
complete inelastic spectrum - resonant, non-resonant and Deep Inelastic
Scattering - is elaborated and compared with experimental data. A
phenomenological extension of the model based on direct fits to data is also
introduced. Within both models, cross sections and response functions are
evaluated and binding energy effects are analyzed. Finally, an investigation of
the second-kind scaling behavior is also presented.Comment: 39 pages, 13 figures; formalism extended and slightly reorganized,
conclusions extended; to appear in Phys. Rev.
Hoarding disorder: A new obsessive-compulsive related disorder in DSM-5
Obsessive-compulsive disorder (OCD) and related disorders have been the subject of significant revisions in the fifth edition of the Diagnostic and Statistical Manual (DSM-5). One of these major changes has been the removal of OCD from the \u2018Anxi- ety Disorders\u2019 section and its instalment in a new and distinct Obsessive-Compulsive and Related Disorders (OCRDs) chap- ter. However, it is the instatement of Hoarding Disorder (HD) as a new OCRD that marks the most significant change. Previously considered a symptom of OCPD, and subsequently linked to OCD, it is now acknowledged that hoarding can emerge inde- pendently from any alternative condition. The present paper provides an updated review of recent investigations supporting the status of HD as an independent nosological entity. Specifi- cally, we will present the new DSM-5 diagnostic criteria and examine the literature pertaining to the psychopathological and phenomenological aspects of the disorder, with particular atten- tion to practical strategies that can help clinicians to recognise and differentiate HD from OCD. Finally, the available assess- ment and treatment strategies for HD are summarised
New Measurements of Nucleon Structure Functions from the CCFR/NuTeV Collaboration
We report on the extraction of the structure functions F_2 and Delta xF_3 =
xF_3nu-xF_3nubar from CCFR neutrino-Fe and antineutrino-Fe differential cross
sections. The extraction is performed in a physics model independent (PMI) way.
This first measurement for Delta xF_3, which is useful in testing models of
heavy charm production, is higher than current theoretical predictions. The F_2
(PMI) values measured in neutrino and muon scattering are in good agreement
with the predictions of Next to Leading Order PDFs (using massive charm
production schemes), thus resolving the long-standing discrepancy between the
two sets of data.Comment: 5 pages. Presented by Arie Bodek at the CIPNAP2000 Conference, Quebec
City, May 200
- …