79 research outputs found
Gamow Shell Model description of Li isotopes and their mirror partners
Background: Weakly bound and unbound nuclei close to particle drip lines are
laboratories of new nuclear structure physics at the extremes of neutron/proton
excess. The comprehensive description of these systems requires an open quantum
system framework that is capable of treating resonant and nonresonant many-body
states on equal footing. Purpose: In this work, we construct the minimal
complex-energy configuration interaction approach to describe binding energies
and spectra of selected 5 A 11 nuclei. Method: We employ the
complex-energy Gamow shell model (GSM) assuming a rigid He core. The
effective Hamiltonian, consisting of a core-nucleon Woods-Saxon potential and a
simplified version of the Furutani-Horiuchi-Tamagaki interaction with the
mass-dependent scaling, is optimized in the sp space. To diagonalize the
Hamiltonian matrix, we employ the Davidson method and the Density Matrix
Renormalization Group technique. Results: Our optimized GSM Hamiltonian offers
a good reproduction of binding energies and spectra with the root-mean-square
(rms) deviation from experiment of 160 keV. Since the model performs well when
used to predict known excitations that have not been included in the fit, it
can serve as a reliable tool to describe poorly known states. A case in point
is our prediction for the pair of unbound mirror nuclei Li-N in
which a huge Thomas-Ehrman shift dramatically alters the pattern of low-energy
excitations. Conclusion: The new model will enable comprehensive studies of
structure and reactions aspects of light drip-line nuclei.Comment: 11 pages, 3 figure
The NUMEN project: NUclear Matrix Elements for Neutrinoless double beta decay
The article describes the main achievements of the NUMEN project togetherwith an updated and detailed overview of the related R&D activities andtheoretical developments. NUMEN proposes an innovative technique to access thenuclear matrix elements entering the expression of the lifetime of the doublebeta decay by cross section measurements of heavy-ion induced Double ChargeExchange (DCE) reactions. Despite the two processes, namely neutrinoless doublebeta decay and DCE reactions, are triggered by the weak and strong interactionrespectively, important analogies are suggested. The basic point is thecoincidence of the initial and final state many-body wave-functions in the twotypes of processes and the formal similarity of the transition operators. Firstexperimental results obtained at the INFN-LNS laboratory for the40Ca(18O,18Ne)40Ar reaction at 270 MeV, give encouraging indication on thecapability of the proposed technique to access relevant quantitativeinformation. The two major aspects for this project are the K800Superconducting Cyclotron and MAGNEX spectrometer. The former is used for theacceleration of the required high resolution and low emittance heavy ion beamsand the latter is the large acceptance magnetic spectrometer for the detectionof the ejectiles. The use of the high-order trajectory reconstructiontechnique, implemented in MAGNEX, allows to reach the experimental resolutionand sensitivity required for the accurate measurement of the DCE cross sectionsat forward angles. However, the tiny values of such cross sections and theresolution requirements demand beam intensities much larger than manageablewith the present facility. The on-going upgrade of the INFN-LNS facilities inthis perspective is part of the NUMEN project and will be discussed in thearticle
The NUMEN project: NUclear Matrix Elements for Neutrinoless double beta decay
The article describes the main achievements of the NUMEN project together with an updated and detailed overview of the related R&D activities and theoretical developments. NUMEN proposes an innovative technique to access the nuclear matrix elements entering the expression of the lifetime of the double beta decay by cross section measurements of heavy-ion induced Double Charge Exchange (DCE) reactions. Despite the two processes, namely neutrinoless double beta decay and DCE reactions, are triggered by the weak and strong interaction respectively, important analogies are suggested. The basic point is the coincidence of the initial and final state many-body wave-functions in the two types of processes and the formal similarity of the transition operators. First experimental results obtained at the INFN-LNS laboratory for the 40Ca(18O,18Ne)40Ar reaction at 270 MeV, give encouraging indication on the capability of the proposed technique to access relevant quantitative information. The two major aspects for this project are the K800 Superconducting Cyclotron and MAGNEX spectrometer. The former is used for the acceleration of the required high resolution and low emittance heavy ion beams and the latter is the large acceptance magnetic spectrometer for the detection of the ejectiles. The use of the high-order trajectory reconstruction technique, implemented in MAGNEX, allows to reach the experimental resolution and sensitivity required for the accurate measurement of the DCE cross sections at forward angles. However, the tiny values of such cross sections and the resolution requirements demand beam intensities much larger than manageable with the present facility. The on-going upgrade of the INFN-LNS facilities in this perspective is part of the NUMEN project and will be discussed in the article.Consejo Europeo de InvestigaciĂłn (ERC)- Horizon 2020 714625 y 65400
Toward the discovery of matter creation with neutrinoless β β decay
The discovery of neutrinoless
β
β
decay could soon be within reach. This hypothetical ultrarare nuclear decay offers a privileged portal to physics beyond the standard model of particle physics. Its observation would constitute the discovery of a matter-creating process, corroborating leading theories of why the Universe contains more matter than antimatter, and how forces unify at high energy scales. It would also prove that neutrinos and antineutrinos are not two distinct particles but can transform into each other, with their mass described by a unique mechanism conceived by Majorana. The recognition that neutrinos are not massless necessitates an explanation and has boosted interest in neutrinoless
β
β
decay. The field stands now at a turning point. A new round of experiments is currently being prepared for the next decade to cover an important region of parameter space. In parallel, advances in nuclear theory are laying the groundwork to connect the nuclear decay with the underlying new physics. Meanwhile, the particle theory landscape continues to find new motivations for neutrinos to be their own antiparticle. This review brings together the experimental, nuclear theory, and particle theory aspects connected to neutrinoless
β
β
decay to explore the path toward, and beyond, its discovery
Perspectives of Nuclear Physics in Europe: NuPECC Long Range Plan 2010
The goal of this European Science Foundation Forward Look into the future of Nuclear Physics is to bring together
the entire Nuclear Physics community in Europe to formulate a coherent plan of the best way to develop the field in
the coming decade and beyond.<p></p>
The primary aim of Nuclear Physics is to understand the origin, evolution, structure and phases of strongly interacting matter, which constitutes nearly 100% of the visible matter in the universe. This is an immensely important and challenging task that requires the concerted effort of scientists working in both theory and experiment, funding agencies, politicians and the public.<p></p>
Nuclear Physics projects are often “big science”, which implies large investments and long lead times. They need careful forward planning and strong support from policy makers. This Forward Look provides an excellent tool to achieve this. It represents the outcome of detailed scrutiny by Europe’s leading experts and will help focus the views of the scientific community on the most promising directions in the field and create the basis for funding agencies to provide adequate support.<p></p>
The current NuPECC Long Range Plan 2010 “Perspectives of Nuclear Physics in Europe” resulted from consultation
with close to 6 000 scientists and engineers over a period of approximately one year. Its detailed recommendations
are presented on the following pages. For the interested public, a short summary brochure has been produced to
accompany the Forward Look.<p></p>
Double Beta Decay, Majorana Neutrinos, and Neutrino Mass
The theoretical and experimental issues relevant to neutrinoless double-beta
decay are reviewed. The impact that a direct observation of this exotic process
would have on elementary particle physics, nuclear physics, astrophysics and
cosmology is profound. Now that neutrinos are known to have mass and
experiments are becoming more sensitive, even the non-observation of
neutrinoless double-beta decay will be useful. If the process is actually
observed, we will immediately learn much about the neutrino. The status and
discovery potential of proposed experiments are reviewed in this context, with
significant emphasis on proposals favored by recent panel reviews. The
importance of and challenges in the calculation of nuclear matrix elements that
govern the decay are considered in detail. The increasing sensitivity of
experiments and improvements in nuclear theory make the future exciting for
this field at the interface of nuclear and particle physics.Comment: invited submission to Reviews of Modern Physics, higher resolution
figures available upon request from authors, Version 2 has fixed typos and
some changes after referee report
Three-Nucleon Forces: Implementation and Applications to Atomic Nuclei and Dense Matter
Recent advances in nuclear structure theory have significantly enlarged the
accessible part of the nuclear landscape via ab initio many-body calculations.
These developments open new ways for microscopic studies of light, medium-mass
and heavy nuclei as well as nuclear matter and represent an important step
toward a systematic and comprehensive understanding of atomic nuclei across the
nuclear chart. While remarkable agreement has been found between different
many-body methods for a given nuclear Hamiltonian, the comparison with
experiment and the understanding of theoretical uncertainties are still
important open questions. The observed discrepancies to experiment indicate
deficiencies in presently used nuclear interactions and operators. Chiral
effective field theory (EFT) allows to systematically derive contributions to
nucleon-nucleon (NN), three-nucleon (3N) and higher-body interactions including
estimates of theoretical uncertainties. While the treatment of NN interactions
in many-body calculations is well established, the calculation of 3N
interactions and their incorporation in ab initio frameworks is still a
frontier. This work reviews in detail recent and current developments on the
derivation and implementation of improved 3N interactions and provides a
comprehensive introduction to fundamental methods for their practical
calculation and representation. We further give an overview of novel and
established methods that facilitate the inclusion and treatment of 3N
interactions in ab initio nuclear structure frameworks and present a selection
of the latest calculations of atomic nuclei as well as nuclear matter based on
state-of-the-art nuclear NN and 3N interactions derived within chiral EFT.
Finally, we discuss ongoing efforts, open questions and future directions.Comment: 148 pages, 77 figures, 9 tables, published versio
Preparations for Quantum Simulations of Quantum Chromodynamics in 1+1 Dimensions: (II) Single-Baryon -Decay in Real Time
A framework for quantum simulations of real-time weak decays of hadrons and
nuclei in a 2-flavor lattice theory in one spatial dimension is presented. A
single generation of the Standard Model is found to require 16 qubits per
spatial lattice site after mapping to spin operators via the Jordan-Wigner
transformation. Both quantum chromodynamics and flavor-changing weak
interactions are included in the dynamics, the latter through four-Fermi
effective operators. Quantum circuits which implement time evolution in this
lattice theory are developed and run on Quantinuum's H1-1 20-qubit trapped ion
system to simulate the -decay of a single baryon on one lattice site.
These simulations include the initial state preparation and are performed for
both one and two Trotter time steps. The potential intrinsic error-correction
properties of this type of lattice theory are discussed and the leading lattice
Hamiltonian required to simulate -decay of nuclei induced by a
neutrino Majorana mass term is provided.Comment: 26 pages, 11 figure
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