Narrow Results

In nuclear physics, the relativistic mean-field theory describes the nucleus as a system of Dirac nucleons which interact via meson fields. In a static case and without nonlinear self-coupling of the σ meson, the relativistic mean-field equations become a system of Dirac equations where the potential is given by the meson and photon fields. The aim of this work is to prove the existence of solutions of these equations. We consider a minimization problem with constraints that involve negative spectral projectors and we apply the concentration-compactness lemma to find a minimizer of this problem. We show that this minimizer is a solution of the relativistic mean-field equations considered.

In this paper, we consider a model for a nucleon interacting with the ω and σ mesons in the atomic nucleus. The model is relativistic, but we study it in the nuclear physics non-relativistic limit, which is of a very different nature from the one of the atomic physics. Ground states with a given angular momentum are shown to exist for a large class of values for the coupling constants and the mesons' masses. Moreover, we show that, for a good choice of parameters, the very striking shapes of mesonic densities inside and outside the nucleus are well described by the solutions of our model.

This work presents results on charged state topology of relativistic fragmentation of ⁶Li and ⁷Li nuclei at 4.5A and 3.8A GeV/c, respectively, on photoemulsion nuclei. The results would make it possible to answer some topical questions concerning the cluster structure of lithium isotopes. The isotopic composition of fragments and the channels of ^6,7Li fragmentation as well as the mean momenta ρβc of projectile fragments have been measured. Yields of ¹H(³He) appear to have the highest probability due to the fragmentation of ⁷Li, while ²H(⁴He) and ¹H(⁴He) are dominant through ⁶Li-fragmentation process. The presence of exotic ⁶He among fragmentation process is observed in ⁷Li with yield 3% while 0.65% were found in ⁶Li.

I discuss how global QCD fits of parton distribution functions (PDFs) can make the somewhat separated fields of high-energy particle physics and lower energy hadronic and nuclear physics interact to the benefit of both. I review specific examples of this interplay from recent works of the CTEQ-Jefferson Lab collaboration, including hadron structure at large parton momentum and gauge boson production at colliders. I devote particular attention to quantifying theoretical uncertainties arising in the treatment of large partonic momentum contributions to deep inelastic scattering (DIS) observables, and to discussing the experimental progress needed to reduce these.

A tribute to Bruno Rossi. A sketch is given of the sparkling period of the research on Cosmic Rays in Florence by Rossi and his Team. The Group of Arcetri flared up as a meteor on the "Tuscan Hill" which has seen Galileo as a solitary giant opening a new era in Physics some centuries before.

Nuclear-structure theory is an important ingredient in the interpretation of many experiments that look for physics beyond the Standard Model. I review the role of nuclear structure in attempts to learn more about neutrinos through double beta-decay and to discover new sources of CP violation through atomic electric-dipole moments.

It has been a natural desire for a long time to be able to describe nuclear physics in terms of the fundamental strong interaction. Recently some significant progress has been made in this area in terms of lattice QCD calculations of simple nuclear physics processes such as nucleon nucleon scattering. An attempt is made to introduce the progress made in this area, to an audience composed mainly of many-body theorists (non-lattice QCD and even non-particle/nuclear physics) interested in inter-disciplinary approaches.

Ettore Majorana was the brightest Italian theoretical physicist of the XX century (actually, Enrico Fermi regarded him as the brightest in the world of his time, and compared him to Galileo and Newton), even if to some people Majorana is often known mainly for his mysterious disappearance, in 1938, when he was 31. In this paper, we present a panoramic view of the main scientific articles published by him, as well as their significance. We also briefly outline his life, the biographical data being based on letters, documents, testimonies discovered or collected by the author during more than four decades, and contained since 1986 in Recami's book quoted in the text. Finally, extensive information and comments are added with regard to the scientific manuscripts left unpublished by Majorana. Two pictures complete the paper.

We present an overview of recent efforts to calculate the interactions among hadrons using lattice QCD. After outlining the techniques that are used to extract scattering parameters, we detail the latest calculations of meson–meson scattering, baryon–baryon scattering and multi-meson systems obtained with domain-wall valence quarks on the staggered MILC lattices by the NPLQCD collaboration. Estimates of the computational resources required to achieve precision results in the baryon sector are presented.

Microscopic local optical potentials from two sources were calculated by folding the numerical g-matrices over point proton and neutron RMF densities of target nuclei. The hard-core Hamada–Johnston and the soft-core Urbana v-14 local inter-nucleon potentials have been used to generate numerical g-matrices by solving Bethe–Goldstone integral equation. The calculated potentials have been used to analyze successfully both the proton and neutron differential elastic scattering and polarization data at 65 MeV over a wide mass region of targets: ¹²C–²⁰⁸Pb. Comparison of the present results with a phenomenological optical model analyzes is also presented. Mass number dependence of the mean square radii of the two microscopic potentials are in close agreement with each other as well as with empirical results.

The experimental search for the formation of the lithium isotope ¹⁰Li was carried out in the inclusive ¹¹B(π^-, p)X and correlation ¹²C(π^-, pp)X, ¹⁴C(π^-, pt)X, ¹⁴C(π^-, dd)X measurements in the stopped π^--meson absorption reactions. Excited states of ¹⁰Li with the resonance energy E_r = 6.1 ± 0.1 MeV, 7.9 ± 0.2 MeV and 10.1 ± 0.1 MeV were observed for the first time.

The thermal conductivity of pionic medium has been evaluated with the help of its standard expression from the relaxation time approximation, where inverse of pion relaxation time or pion thermal width has been obtained from the imaginary part of pion self-energy. In the real-time formalism of thermal field theory, the finite temperature calculations of pion self-energy for πσ and πρ loops have been done. The numerical value of our thermal conductivity increases with temperature very softly, though at particular temperature, our estimation has to consider a large band of phenomenological uncertainty.

Theoretical and computational frameworks of complexity science are dominated by binary structures. This binary bias, seen in the ubiquity of pair-wise networks and formal binary operations in mathematical models, limits our capacity to faithfully capture irreducible polyadic interactions in higher-order systems. A paradigmatic example of a higher-order interaction is the Borromean link of three interlocking rings. In this paper, we propose a mathematical framework via hypergraphs and hypermatrix algebras that allows to formalize such forms of higher-order bonding and connectivity in a parsimonious way. Our framework builds on and extends current techniques in higher-order networks — still mostly rooted in binary structures such as adjacency matrices — and incorporates recent developments in higher-arity structures to articulate the compositional behavior of adjacency hypermatrices. Irreducible higher-order interactions turn out to be a widespread occurrence across natural sciences and socio-cultural knowledge representation. We demonstrate this by reviewing recent results in computer science, physics, chemistry, biology, ecology, social science, and cultural analysis through the conceptual lens of irreducible higher-order interactions. We further speculate that the general phenomenon of emergence in complex systems may be characterized by spatio-temporal discrepancies of interaction arity.

Jerry Duggan was an experimental MeV-accelerator-based nuclear and atomic physicist who, over the past few decades, played a key role in the important transition of this field from basic to applied physics. His fascination for and application of particle accelerators spanned almost 60 years, and led to important discoveries in the following fields: accelerator-based analysis (accelerator mass spectrometry, ion beam techniques, nuclear-based analysis, nuclear microprobes, neutron techniques); accelerator facilities, stewardship, and technology development; accelerator applications (industrial, medical, security and defense, and teaching with accelerators); applied research with accelerators (advanced synthesis and modification, radiation effects, nanosciences and technology); physics research (atomic and molecular physics, and nuclear physics); and many other areas and applications. Here we describe Jerry’s physics education at the University of North Texas (B. S. and M. S.) and Louisiana State University (Ph.D.). We also discuss his research at UNT, LSU, and Oak Ridge National Laboratory, his involvement with the industrial aspects of accelerators, and his impact on many graduate students, colleagues at UNT and other universities, national laboratories, and industry and acquaintances around the world. Along the way, we found it hard not to also talk about his love of family, sports, fishing, and other recreational activities. While these were significant accomplishments in his life, Jerry will be most remembered for his insight in starting and his industry in maintaining and growing what became one of the most diverse accelerator conferences in the world — the International Conference on the Application of Accelerators in Research and Industry, or what we all know as CAARI. Through this conference, which he ran almost single-handed for decades, Jerry came to know, and became well known by, literally thousands of atomic and nuclear physicists, accelerator engineers and vendors, medical doctors, cultural heritage ... the list goes on and on. While thousands of his acquaintances already miss Jerry, this is being felt most by his family and us (B.D. and F.D.M).

The birth of nuclear physics in the 1920s and its culmination in the 1940s which changed human history forever is reviewed in broad touches. I briefly mention further developments of nuclear physics connecting it to modern astrophysics, high-energy physics, etc.

Nuclear-structure theory is an important ingredient in the interpretation of many experiments that look for physics beyond the Standard Model. I review the role of nuclear structure in attempts to to learn more about neutrinos through double beta-decay and to discover new sources of CP violation through atomic electric-dipole moments.

It has been a natural desire for a long time to be able to describe nuclear physics in terms of the fundamental strong interaction. Recently some significant progress has been made in this area in terms of lattice QCD calculations of simple nuclear physics processes such as nucleon nucleon scattering. An attempt is made to introduce the progress made in this area, to an audience composed mainly of many-body theorists (non-lattice QCD and even non-particle/nuclear physics) interested in inter-disciplinary approaches.

Jerry Duggan was an experimental MeV-accelerator-based nuclear and atomic physicist who, over the past few decades, played a key role in the important transition of this field from basic to applied physics. His fascination for and application of particle accelerators spanned almost 60 years, and led to important discoveries in the following fields: accelerator-based analysis (accelerator mass spectrometry, ion beam techniques, nuclear-based analysis, nuclear microprobes, neutron techniques); accelerator facilities, stewardship, and technology development; accelerator applications (industrial, medical, security and defense, and teaching with accelerators); applied research with accelerators (advanced synthesis and modification, radiation effects, nanosciences and technology); physics research (atomic and molecular physics, and nuclear physics); and many other areas and applications. Here we describe Jerry’s physics education at the University of North Texas (B. S. and M. S.) and Louisiana State University (Ph.D.). We also discuss his research at UNT, LSU, and Oak Ridge National Laboratory, his involvement with the industrial aspects of accelerators, and his impact on many graduate students, colleagues at UNT and other universities, national laboratories, and industry and acquaintances around the world. Along the way, we found it hard not to also talk about his love of family, sports, fishing, and other recreational activities. While these were significant accomplishments in his life, Jerry will be most remembered for his insight in starting and his industry in maintaining and growing what became one of the most diverse accelerator conferences in the world — the International Conference on the Application of Accelerators in Research and Industry, or what we all know as CAARI. Through this conference, which he ran almost single-handed for decades, Jerry came to know, and became well known by, literally thousands of atomic and nuclear physicists, accelerator engineers and vendors, medical doctors, cultural heritage ... the list goes on and on. While thousands of his acquaintances already miss Jerry, this is being felt most by his family and us (B.D. and F.D.M).

The following sections are included:

• IWARA 2007 in a Nutshell
  • Gravitation, cosmology and mathematical physics
  • Nuclear physics, hadrons and QCD
  • Astronomy and astrophysics

• Conclusions

• Acknowledgments

The DESIR collaboration proposes the construction of a low-energy beam facility at GANIL-SPIRAL2 to study the properties of exotic nuclei in unexplored regions of the nuclide chart. Beam preparation devices including gas catchers, radiofrequency quadrupoles, high resolution separators and ion traps are under construction in order to provide high quality beams to the users. The DESIR Physics program addresses by means of complementary experimental techniques most of the current interrogations regarding the structure of exotic nuclei, the fundamental interactions driving their properties, as well as their formation in the universe.