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In the present work, the isovector dipole responses, both in the resonance region and in the low-energy sector, are investigated using the microscopic nuclear Energy Density Functionals (EDFs). The self-consistent QRPA model based on Skyrme Hartree Fock BCS approach is applied to study the evolution of the isovector dipole strength by increasing neutron number and temperature. First, the isovector dipole strength and excitation energies are investigated for the Ni isotopic chain at zero temperature. The evolution of the low-energy dipole strength is studied as a function of the neutron number. In the second part, the temperature dependence of the isovector dipole excitations is studied using the self-consistent finite temperature QRPA, below and above the critical temperatures. It is shown that new excited states become possible due to the thermally occupied states above the Fermi level, and opening of the new excitations channels. In addition, temperature leads to fragmentation of the low-energy strength around the neutron separation energies, and between 9 and 12 MeV. We find that the cumulative sum of the strength below E ≤ 12 MeV decreases in open-shell nuclei due to the vanishing of the pairing correlations as temperature increases up to T = 1 MeV. The analysis of the transition densities in the low-energy region shows that the proton and neutron transition densities display a mixed pattern: both isoscalar and isovector motion of protons and neutrons are obtained inside nuclei, while the neutron transition density is dominant at the surface region. [ABSTRACT FROM AUTHOR]

In this contribution, we report some recent progress in our understanding of particle-vibration coupling (PVC) in nuclei. In particular, we first review the formal development that has allowed some of us to deduce the PVC equations within the Green's functionmethod. Applications are then discussed, both in the case of single-particle states and giant resonances in magic nuclei. We also present a new model that extends the PVC ansatz and is meant to account for the complete low-lying spectra of odd nuclei. [ABSTRACT FROM AUTHOR]

In this contribution, we review some works related with the extraction of the symmetry energy parameters from isovector nuclear excitations, like the giant resonances. Then, we move to the general issue of how to assess whether correlations between a parameter of the nuclear equation of state and a nuclear observable are robust or not. To this aim, we introduce the covariance analysis and we discuss some counter-intuitive, yet enlightening, results from it. [ABSTRACT FROM AUTHOR]

The scope of the paper is to apply a state-of-the-art beyond mean-field model to the description of the Gamow-Teller response in atomic nuclei. This topic recently attracted considerable renewed interest, due, in particular, to the possibility of performing experiments in unstable nuclei. We study the cases of 48Ca,78Ni,132Sn, and 208Pb. Our model is based on a fully self-consistent Skyrme Hartree-Fock plus random phase approximation. The same Skyrme interaction is used to calculate the coupling between particles and vibrations, which leads to the mixing of the Gamow-Teller resonance with a set of doorway states and to its fragmentation. We compare our results with available experimental data. The microscopic coupling mechanism is also discussed in some detail. [ABSTRACT FROM AUTHOR]

The properties of single-particle states in the magic nuclei 40Ca and 208Pb, in particular the energies, spectroscopic factors, and the effective mass, have been studied in a fully self-consistent particle-vibration coupling (PVC) approach within the framework of Skyrme energy density functional theory. All selected phonons are obtained by the random phase approximation, and the same Skyrme interaction is also used in the PVC vertex. We focus on the effect of the noncentral two-body spin-orbit and tensor interactions on the single-particle properties. It has been found that the contributions of those terms are important to improve the results for 208Pb. The calculated single-particle energies and spectroscopic factors are compared to available experimental data. The single-particle level density around the Fermi surface is significantly increased due to the effect of PVC. [ABSTRACT FROM AUTHOR]

Although many random-phase approximation (RPA) calculations of the Gamow-Teller (GT) response exist, this is not the case for calculations going beyond the mean-field approximation. We apply a consistent model, that includes the coupling of the GT resonance to low-lying vibrations, to nuclei of the fp shell. Among other motivations, our goal is to see if the particle-vibration coupling can redistribute the low-lying GT+ strength that is relevant for electron-capture processes in core-collapse supernova. We conclude that the lowering and fragmentation of that strength are consistent with the experimental findings and validate our model. However, the particle-vibration coupling cannot account for the quenching of the total value of the low-lying strength. [ABSTRACT FROM AUTHOR]

The nuclear structure community is striving to determine a nuclear energy functional which is as universal and as accurate as possible. When a functional is determined by fitting free parameters, the constraints on these parameters coming from excited states (like the well-known giant resonances) are not, as a rule, imposed. This work shows that at least three constraints could be imposed on Skyrme functionals, by explaining the physical background and discussing their relevance. [ABSTRACT FROM AUTHOR]

Mean field schemes, from simple Hartree—Fock plus random phase approximation calculations of the ground and excited states to more sophisticated approaches which include pairing as well, have been popular for quite a long time. In these models, the input is an effective interaction. We still lack a precise link between this interaction and a more fundamental theory; however, there have been various new recent attempts to correlate empirical pieces of evidence about nuclear (and neutron) matter, or experimental results, with the properties of the effective interactions. In this contribution, we claim that, while we have indeed made some progress in our understanding of certain features of the interactions, we are still missing a clue about its proper density dependence and about its isovector properties. [ABSTRACT FROM AUTHOR]

Microscopic calculations of nuclear states excited by means of charge-exchange reactions and involving spin and isospin degrees of freedom, in particular, of the Gamow—Teller and the spin—dipole resonances, are discussed. The framework is a fully self-consistent nonrelativistic spherical quasiparticle random-phase approximation constructed on top of the Hartree—Fock—Bardeen—Cooper—Schrieffer approach. Our results are compared with available experimental data, and a critical discussion is attempted. [ABSTRACT FROM AUTHOR]

In the present contribution, we discuss the relevance of fully self-consistent HF plus RPA (or HF-BCS plus QRPA) calculations based on Skyrme effective forces, and their impact on our present knowledge of basic properties of the nuclear equation of state, like the incompressibilty and the symmetry energy. Finally, we address the problem whether correlations beyond mean field can alter the picture obtained at the (Q)RPA level. Throghout the paper, the comparison with the results obtained using Gogny forces, or RMF Lagrangians, will be emphasized. [Copyright &y& Elsevier]

Abstract: We study the role of the tensor term of the Skyrme effective interactions on the spin–orbit splittings in the isotones and isotopes. The different role of the triplet-even and triplet-odd tensor forces is pointed out by analyzing the spin–orbit splittings in these nuclei. The experimental isospin dependence of these splittings cannot be described by Hartree–Fock calculations employing the usual Skyrme parametrizations, but is very well accounted for when the tensor interaction is introduced. The capability of the Skyrme forces to reproduce binding energies and charge radii in heavy nuclei is not destroyed by the introduction of the tensor term. Finally, we also discuss the effect of the tensor force on the centroid of the Gamow–Teller states. [Copyright &y& Elsevier]

The status of the theoretical research on the compressional modes of finite nuclei and the incompressibility K∞ of nuclear matter, is reviewed. It is argued that the recent experimental data on the Isoscalar Giant Monopole Resonance (ISGMR) allow extracting the value of K∞ with an uncertainity of about ± 12 MeV. Non-relativistic (Skyrme, Goguy) and relativistic mean field models predict for K∞ values which are significantly different from one another, namely ≈ 220–235 and 250–270 MeV respectively. It is shown that the solution of this puzzle requires a better determination of the symmetry energy at, and around, saturation. The role played by the experimental data of the Isoscalar Giant Dipole Resonance (ISGDR) is also discussed. [Copyright &y& Elsevier]

Isoscalar monopole and dipole resonances in [sup 90]Zr, [sup 116]Sn, [sup 144]Sm, and [sup 208]Pb are studied within the framework of self-consistent HF-RPA or HF-BCS plus quasiparticle RPA. A comparison with recent experimental data obtained at Texas A&M University, as well as the problems related to the determination of the nuclear incompressibility K[sub ∞], is discussed. [ABSTRACT FROM AUTHOR]

We present a study on the isoscalar quadrupole strength in tin nuclei, focusing mainly on the low-energy region. The calculations are performed using the Skyrme-type energy density functionals within the fully self-consistent quasiparticle random phase approximation, allowing for a good description of the experimental data for the first 2+ state and the isoscalar giant quadrupole resonance. It is found that the first 2+ state and the low-energy quadrupole states between 3 and 6 MeV display an opposite behavior with increasing neutron number. While the strength of the first 2+ state decreases, some excited states start to accumulate between 3 and 6 MeV, and increase their strength with increasing neutron number. This low-energy region between 3 and 6 MeV is quite sensitive to the changes in the shell structure with increasing neutron number. In particular, between 116Sn and 132Sn, the filling of the neutron orbitals with large values of j, has an important impact on the low-energy region. Our analysis shows that the low-energy states have a noncollective character, except the first 2+ state. In addition, the states in the low-energy region above 5 MeV display an interesting pattern: with the increase of the neutron number, their strength increases and their nature changes, namely they switch from proton excitations to neutron-dominated one. We conclude that the low-energy quadrupole states between 3 and 6 MeV can provide information about the shell evolution in open-shell nuclei. [ABSTRACT FROM AUTHOR]

We analyze and propose a solution to the apparent inconsistency between our current knowledge of the equation of state of asymmetric nuclear matter, the energy of the isobaric analog state (IAS) in a heavy nucleus such as 208Pb, and the isospin symmetry breaking forces in the nuclear medium. This is achieved by performing state-of-the-art Hartree-Fock plus random phase approximation calculations of the IAS that include all isospin symmetry breaking contributions. To this aim, we propose a new effective interaction that is successful in reproducing the IAS excitation energy without compromising other properties of finite nuclei. [ABSTRACT FROM AUTHOR]

Background: Minimally invasive surgery (MIS) in medial displacement calcaneus osteotomy (MDCO) has been proposed for surgical correction of adult-acquired flat foot deformity (AAFD) to reduce complications of open approaches. The aim of our study is to systematically analyze complications and the clinical and radiological results of MIS- MDCO. Methods: A systematic review of the English literature was performed on 30th October 2023. Randomized controlled trials and non-randomized trials, cohort studies, case–control studies and case series concerning surgical correction of AAFD with MIS-MDCO and with at least 15 patients were included. Case reports, technical notes, animal or cadaveric studies were excluded. The quality and risk of bias of the studies included were evaluated using GRADE and MINORS systems. Complications rate, clinical and radiological results were inferred from the studies included. Results: Nine articles were included. A total of 501 cases treated with MIS-MDCO were analysed with a mean follow-up of 11.9 ± 5.1 months. The reported wound infection rate was about 3% and sural neuropathy was rated about 1%. Only 4% of the cases required removal of the screw for pain. In the comparative studies (MIS versus Open MDCO), comparable clinical results but with significant differences (P < 0.001) in infection rates (1% versus 14%) and sural neuropathy (2% versus 1%) were observed. Conclusion: AAFD correction performed with MIS-MDCO, with the limitation of a poor quality and high risk of bias of the included studies, seems to provide good clinical results and high subjective satisfaction with a lower complication rate compared to open approach. Further high-quality long-term comparative studies could better clarify complications and clinical and radiological outcomes of the MIS technique in the treatment of AAFD. Level of evidence: Level IV. [ABSTRACT FROM AUTHOR]

The effect of temperature on the evolution of the isovector dipole and isoscalar quadrupole excitations in 68Ni and 120Sn nuclei is studied within the fully self-consistent finite temperature quasiparticle random phase approximation framework, based on the Skyrme-type SLy5 energy density functional. The new low-energy excitations emerge due to the transitions from thermally occupied states to the discretized continuum at finite temperatures, whereas the isovector giant dipole resonance is not strongly impacted by the increase of temperature. The radiative dipole strength at low energies is also investigated for the 122Sn nucleus, becoming compatible with the available experimental data when the temperature is included. In addition, both the isoscalar giant quadrupole resonance and low-energy quadrupole states are sensitive to the temperature effect: while the centroid energies decrease in the case of the isoscalar giant quadrupole resonance, the collectivity of the first 2+ state is quenched and the opening of new excitation channels fragments the low-energy strength at finite temperatures. [ABSTRACT FROM AUTHOR]

In this work, we introduce a new approach which is meant to be a first step towards complete self-consistent low-lying spectroscopy of odd nuclei. So far, we essentially limit ourselves to the description of a double-magic core plus an extra nucleon. The model does not contain any free adjustable parameter and is instead based on a Hartree-Fock (HF) description of the particle states in the core, together with self-consistent random-phase approximation (RPA) calculations for the core excitations. We include both collective and noncollective excitations, with proper care of the corrections due to the overlap between them (i.e., due to the nonorthonormality of the basis). As a consequence, with respect to traditional particle-vibration coupling calculations in which one can only address single-nucleon states and particle-vibration multiplets, we can also describe states of shell-model types like 2 particle-1 hole. We will report results for 49Ca and 133Sb and discuss future perspectives. [ABSTRACT FROM AUTHOR]

The couplings between particles and vibrations in atomic nuclei play a key role in the understanding of various nuclear properties, as it has been highlighted along several decades. In this contribution, after a short survey of the early discoveries of particle-phonon multiplets around the 208Pb region, we review recent experiments and theoretical attempts to understand low-energy spectra of odd-nuclei close to magic and semi-magic cores, where particle-phonon coupling phenomena play a significant role. The focus will be on nuclei around 48Ca , 132Sn , 208Pb and neutron-rich Ni isotopes. Special emphasis will be given to experimental techniques based on high-resolution γ -spectroscopy and to recent theoretical developments aimed at disentangling particle-phonon coupled states and other more hybrid configurations, using the Hybrid Configuration Mixing model that has been recently proposed by the Milano group. [ABSTRACT FROM AUTHOR]

We propose a self-consistent quasiparticle random-phase approximation (QRPA) plus quasiparticle-vibration coupling (QPVC) model with Skyrme interactions to describe the width and the line shape of giant resonances in open-shell nuclei, in which the effect of superfluidity should be taken into account in both the ground state and the excited states. We apply the new model to the Gamow-Teller resonance in the superfluid nucleus 120Sn, including both the isoscalar spin-triplet and the isovector spin-singlet pairing interactions. The strength distribution in 120Sn is well reproduced and the underlying microscopic mechanisms, related to QPVC and also to isoscalar pairing, are analyzed in detail. [ABSTRACT FROM AUTHOR]

The nuclear β -decay half-lives of Ni and Sn isotopes, around the closed shell nuclei 78 Ni and 132 Sn, are investigated by computing the distribution of the Gamow–Teller strength using the Quasiparticle Random Phase Approximation (QRPA) with quasiparticle-vibration coupling (QPVC), based on ground-state properties obtained by Hartree–Fock–Bogoliubov (HFB) calculations. We employ the effective interaction SkM ⁎ and a zero-range effective pairing force. The half-lives are strongly reduced by including the QPVC. We study in detail the effects of isovector (IV) and isoscalar (IS) pairing. Increasing the IV strength tends to increase the lifetime for nuclei in the proximity of, but lighter than, the closed-shell ones in QRPA calculations, while the effect is significantly reduced by taking into account the QPVC. On the contrary, the IS pairing mainly plays a role for nuclei after the shell closure. Increasing its strength decreases the half-lives, and the effect at QRPA and QRPA+QPVC level is comparable. The effect of IS pairing is particularly pronounced in the case of the Sn isotopes, where it turns out to be instrumental to obtain good agreement with experimental data. [ABSTRACT FROM AUTHOR]

We investigate the impact of the neutron-skin thickness ΔRnp on the energy difference between the anti-analog giant dipole resonance (AGDR), EAGDR, and the isobaric analog state (IAS), EIAS, in a heavy nucleus such as 208Pb. For guidance, we first develop a simple and analytic, yet physical, approach based on the Droplet Model that linearly connects the energy difference EAGDR-EIAS with ΔRnp. To test this correlation on more fundamental grounds, we employ a family of systematically varied Skyrme energy density functionals where variations on the value of the symmetry energy at saturation density J are explored. The calculations have been performed within the fully self consistent Hartree-Fock (HF) plus charge-exchange random phase approximation (RPA) framework. We confirm the linear correlation within our microscopic apporach and, by comparing our results with available experimental data in 208Pb, we find that our analysis is consistent with ΔRnp = 0.204±0.009 fm, J = 31.4±0.5 MeV and a slope parameter of the symmetry energy at saturation of L = 76.4±5.4 MeV - the attached errors correspond to a lower-limit estimate of the systematic plus experimental uncertainties. These results are in agreement with those extracted from different experimental data albeit, L and ΔRnp are somewhat large when compared to previous estimations based on giant resonance studies. Possible hints whether model dependence can explain this difference are provided. [ABSTRACT FROM AUTHOR]

Nuclear β decay in magic nuclei is investigated, taking into account the coupling between particles and collective vibrations, on top of self-consistent random phase approximation calculations based on Skyrme density functionals. The low-lying Gamow-Teller strength is shifted downwards and at times becomes fragmented; as a consequence, the β-decay half-lives are reduced due to the increase of the phase space available for the decay. In some cases, this leads to a very good agreement between theoretical and experimental lifetimes: this happens, in particular, in the case of the Skyrme force SkM* that can also reproduce the line shape of the high-energy Gamow-Teller resonance as was previously shown. [ABSTRACT FROM AUTHOR]

The Gamow-Teller (GT) strength distributions and isobaric analog resonance (IAR) states of several N = Z + 2 nuclei with mass number A = 42 - 58 are studied by using a self-consistent Skyrme Hartree-Fock-Bogoliubov method plus quasiparticle random phase approximation (HFB+QRPA) formalism. The isoscalar spin-triplet pairing interaction is included in QRPA on top of the isovector spin-singlet one in the HFB method. It is found that the isoscalar pairing correlations mix largely the (νj> → πj<) configurations into the low-energy states, and this mixing plays an important role in the formation and in the collectivity of these low-energy states. Furthermore, the observed excitation energy of the low-energy GT state with respect to the IAR can be well reproduced when the strength of isoscalar pairing is about 1.0-1.05 times that of the isovector pairing, irrespective of the adopted Skyrme interactions. In N = Z + 2 nuclei in the middle of the pf-shell, a mutual cooperative effect of isoscalar pairing and tensor interaction is found; namely, the tensor force reduces the spin-orbit splittings and enhances the effect of the isoscalar pairing. [ABSTRACT FROM AUTHOR]

We study the electric dipole polarizability αD in 208Pb based on the predictions of a large and representative set of relativistic and nonrelativistic nuclear mean-field models. We adopt the droplet model as a guide to better understand the correlations between αD and other isovector observables. Insights from the droplet model suggest that the product of αD and the nuclear symmetry energy at saturation density J is much better correlated with the neutron skin thickness Δrnp of 208Pb than the polarizability alone. Correlations of αDJ with &#Δrnp and with the symmetry energy slope parameter L suggest that αDJ is a strong isovector indicator. Hence, we explore the possibility of constraining the isovector sector of the nuclear energy density functional by comparing our theoretical predictions against measurements of both αD and the parity-violating asymmetry in 208Pb. We find that the recent experimental determination of αD in 208Pb in combination with the range for the symmetry energy at saturation density J = [31 ± (2)est] MeV suggests Δrnp(208Pb) = 0.165 ± (0.009)expt ± (0.013)theor ± (0.021)est fm and L = 43 ± (6)expt ± (8)theor ± (12)est MeV. [ABSTRACT FROM AUTHOR]

The isoscalar giant monopole resonance (ISGMR) in Cd, Sn, and Pb isotopes has been studied within the self-consistent Skyrme Hartree-Fock + BCS and quasiparticle random phase approximation (QRPA). Three Skyrme parameter sets are used in the calculations (i.e., SLy5, SkM*, and SkP) since they are characterized by different values of the compression modulus in symmetric nuclear matter; namely, K∞ = 230,217, and 202 MeV, respectively. We also investigate the effect of different types of pairing forces on the ISGMR in Cd, Sn, and Pb isotopes. The various calculated energies and the strength distributions of the ISGMR are compared with available experimental data. We find that SkP underestimates the various energies for all isotopes due to its low value of the nuclear matter incompressibility; namely, K∞ = 202 MeV. However, it can give a better description on the constrained energies for Cd isotopes and a reasonable peak energy for some nuclei. On the other hand, the SLy5 parameter set, supplemented by an appropriate pairing interaction, gives a reasonable description of the scaling energies in Cd and Sn isotopes and a good centroid energy in Pb isotopes. A better description of ISGMR in Cd and Sn isotopes is achieved by the SkM* interaction, which has a somewhat softer value of the nuclear incompressibility. [ABSTRACT FROM AUTHOR]

The recent high-resolution measurement of the electric dipole (El) polarizability aD in 208Pb [A. Tamii et al., Phys. Rev. Lett. 107, 062502 (2011)] provides a unique constraint on the neutron-skin thickness of this nucleus. The neutron-skin thickness rskin of 208Pb is a quantity of critical importance for our understanding of a variety of nuclear and astrophysical phenomena. To assess the model dependence of the correlation between αD and rskin, we carry out systematic calculations for 208Pb, 132Sn, and 48Ca based on the nuclear density functional theory using both nonrelativistic and relativistic energy density functionals. Our analysis indicates that whereas individual models exhibit a linear dependence between αD and rskjn, this correlation is not universal when one combines predictions from a host of different models. By averaging over these model predictions, we provide estimates with associated systematic errors for rskin and αD for the nuclei under consideration. We conclude that precise measurements of rskin in both 48Ca and 208Pb--combined with the recent measurement of αD--should significantly constrain the isovector sector of the nuclear energy density functional. [ABSTRACT FROM AUTHOR]

The multipole dependent effects induced by tensor correlations on the charge-exchange spin-dipole (SD) modes of the light nucleus 16O are studied within a Hartree-Fock (HF) plus self-consistent random-phase approximation (RPA), using Skyrme-type interactions. The role played by the triplet-even and triplet-odd tensor terms are examined separately to explain either the softening or hardening of the excitation energies of SD modes. The unperturbed and RPA summed strengths, calculated with and without the tensor force, are discussed and compared with the results of shell-model calculations. [ABSTRACT FROM AUTHOR]

We present a systematic analysis of the effects induced by tensor correlations on low-lying collective states of magic nuclei, by using the fully self-consistent random phase approximation (RPA) model with Skyrme interactions. The role of the tensor correlations is analyzed in detail in the case of quadrupole (2+) and octupole (3-) low-lying collective states in 208Pb. The example of 40Ca is also discussed, as well as the case of magnetic dipole states (1+). [ABSTRACT FROM AUTHOR]

Accurate assessment of the value of the incompressibility coefficient, K, of symmetric nuclear matter, which is directly related to the curvature of the equation of state (EOS), is needed to extend our knowledge of the EOS in the vicinity of the saturation point. We review the current status of K as determined from experimental data on isoscalar giant monopole and dipole resonances (compression modes) in nuclei, by employing the microscopic theory based on the random-phase approximation (RPA). [ABSTRACT FROM AUTHOR]

Abstract: A nuclear structure model based on linear response theory (i.e., random phase approximation) and which includes pairing correlations and anharmonicities (coupling with collective vibrations), has been implemented in such a way that it can be applied on the same footing to magic as well as open-shell nuclei. As applications, we have chosen to study the dipole excitations both in well known, stable isotopes like 208Pb and 120Sn as well as in the neutron-rich, unstable 132Sn nucleus, by addressing in the latter case the question about the nature of the low-lying strength. Our results suggest that the model is reliable and predicts in all cases low-lying strength of non collective nature. [Copyright &y& Elsevier]

We calculate, for the first time, the state-dependent pairing gap of a finite nucleus (120Sn) diagonalizing the bare nucleon-nucleon potential (Argonne v14) in a Hartree-Fock basis (with effective k-mass mk &ap; 0.7m), within the framework of the generalized Bogoliubov-Valatin approximation including scattering states up to 800 MeV above the Fermi energy to achieve convergence. The resulting gap accounts for about half of the experimental gap. The combined effect of the bare nucleon-nucleon potential and of the induced pairing interaction arising from the exchange of low-lying surface vibrations between nucleons moving in time-reversal states close to the Fermi energy accounts for the experimental gap. [ABSTRACT FROM AUTHOR]

The exchange of low-lying collective vibrations between pairs of nucleons moving in time reversal states close to the Fermi energy provides a conspicuous contribution to the nuclear pairing interaction, which accounts for 30-50% of the pairing gap in the case of nuclei along the stability valley, and to essentially all of the pairing correlations of the most loosely bound nucleons in the case of halo nuclei. [ABSTRACT FROM AUTHOR]

We present new theoretical results of the flux-averaged [sup 12]C(ν[sub e], e[sup -])[sup 12]N and [sup 12]C(ν[sub μ], mu;[sup -])[sup 12]N cross sections with ν[sub μ](ν[sub e]) coming from the decay-in-flight (decay-at-rest) of π[sup +](μ[sup +]). These cross sections are relevant for the interpretation of the recent experiments on neutrino oscillation performed by the LSND and KARMEN collaborations. The microscopic approaches used are charge-exchange random phase approximation (RPA), charge-exchange RPA among quasiparticles (QRPA), and the Shell Model. We show that the exclusive cross sections are in nice agreement with the experimental values for both reactions when a large-scale shell-model calculation is performed. Concerning the inclusive cross section for ν[sub μ] coming from the decay-in-flight of π[sup +], the calculated value keeps overestimating the experimental one by 20-30%, while the inclusive cross section due to ν[sub e] coming from the decay-at-rest of μ[sup +] is in agreement within experimental error bars with the measured values. The shell-model prediction for the decay-in-flight neutrino cross section is reduced compared to the RPA one because of the different kind of correlations in the calculation of the spin modes (in particular, the quenching of the 1[sup +]) and partially due to the shell-model configuration basis, which is not large enough, as we show using arguments based on sum rules. [ABSTRACT FROM AUTHOR]

In this paper we apply Nuclear Field Theory techniques to describe the 123Te K-electron capture, whose half-life is reported to be the longest one ever measured in a single β decay. The theoretical half-life we obtain varies in the range (6.0 × 1019 − 8.9 × 1019)yr, which overestimates by a factor 3–4 the experimental one. [ABSTRACT FROM AUTHOR]

The Gamow–Teller strength distributions of 116 Sb and 122 Sb were measured with the 116 , 122 Sn (3 He , t) 116 , 122 Sb charge-exchange reactions at 140 MeV/u . The measurements were carried out at the Research Center for Nuclear Physics (RCNP) at Osaka University in Osaka, Japan using the Grand Raiden spectrometer. The data were analysed by Multipole-Decomposition Analysis (MDA). The Gamow–Teller strengths summed up to 28 MeV are (38 ± 7) % and (48 ± 6) % of the Ikeda sum rule for 116 Sb and 122 Sb , respectively, if the quasi-free scattering (QFS) contribution is not subtracted. These percentages are (29 ± 7) % and (35 ± 5) % , respectively, if the QFS contribution is maximally subtracted. These results were compared to those from previous measurements of the same isotopes, to recent measurements of 150 Pm , and to a Quasi-particle Random-Phase Approximation (QRPA) calculation with Quasi-Particle Vibration Coupling (QPVC). The data suggest that the true QFS contribution is small for 116 Sb , but are inconclusive about whether the QFS contribution is small or significant for 122 Sb . Therefore, these data may provide an interesting test for the general quenching phenomenon of the Gamow–Teller Resonance (GTR). However, more research to reveal the nature of the QFS contribution is still needed on both the experimental and the theoretical side. [ABSTRACT FROM AUTHOR]

We study double charge-exchange phonon states in neutron-rich nuclei, in particular the double isobaric analog states and the double Gamow-Teller excitations, induced by the double isospin operator ∑i,j=1At-(i)t-(j) and spin-isospin operator ∑i,j=1Aσ(i)t-(i)σ(j)t-(j), respectively. We employ quartic commutator relations to evaluate the average energies EDIAS-2EIAS and EDGTR-EDIAS-2(EGTR-EIAS), and conventional double commutator relations to evaluate the average energies of EGTR-EIAS and EIAS. We have found that the corrections from quartic commutators follow the approximate laws: EDIAS-2EIAS≈3/2A-1/3MeV and EDGTR-EDIAS-2(EGTR-EIAS)≈16A-1MeV. While the former is dominated by direct Coulomb effects because Coulomb exchange cancels out to some extent with isospin symmetry breaking contributions originated from the nuclear strong force, the latter is sensitive to the difference in strength between the spin and spin-isospin channels of the strong interaction. [ABSTRACT FROM AUTHOR]

One of the few exact results for the description of the time evolution of an inhomogeneous, interacting many-particle system is given by the harmonic potential theorem (HPT). The relevance of this theorem is that it sets a tight constraint on time-dependent many-body approximations. In this contribution, we show that the original formulation of the HPT is valid also for the case of spin-, velocity-, and density-dependent interactions. This result is completely general and relevant, among the rest, for nuclear structure theory both in the case of ab initio and of more phenomenological approaches. As an example, we report on a numerical implementation by testing the small-amplitude limit of the time-dependent Hartree-Fock--also known as the random phase approximation--for the translational frequencies of a neutron system trapped in a harmonic potential. [ABSTRACT FROM AUTHOR]

We perform time-dependent Hartree-Fock (TDHF) calculations, employing Skyrme functionals, to investigate the small amplitude dipole response of selected neutron-rich nuclei and Sn isotopes. A detailed comparison with the dipole strength predicted by random-phase approximation calculations is presented for the first time. TDHF results are also confronted to Vlasov calculations, to explore up to which extent a semiclassical picture can explain the properties of the nuclear response. The focus is on the low-energy response, below the giant dipole resonance region, where different modes of nonnegligible strength are identified. We show that the relative weight of these excitations evolves with nuclear global features, such as density profile and neutron skin, which in turn reflect important properties of the nuclear effective interaction. A thorough analysis of the associated transition densities turns out to be quite useful to better characterize the mixed isoscalar (IS)-isovector (IV) nature of the different modes and their surface/volume components. In particular, we show that the dipole response in the so-called pygmy dipole resonance region corresponds to isoscalarlike surface oscillations, of larger strength in nuclei with a more diffuse surface. The ratio between the IV and IS energy-weighted sum rule fractions exhausted in this region is shown to almost linearly increase with the neutron skin thickness in Sn isotopes. [ABSTRACT FROM AUTHOR]

Absolute differential cross sections for elastic p 7 Be and p 8 B small-angle scattering were measured in inverse kinematics at an energy of 0.7 GeV/u at GSI Darmstadt. The hydrogen-filled ionization chamber IKAR was used as an active target to detect the recoil protons. The projectile tracking and isotope identification were performed with multi-wire proportional chambers and scintillation detectors. The measured cross sections were analysed using the Glauber multiple-scattering theory. The root-mean-square (rms) nuclear matter radii R m = 2.42 (4) fm for 7Be and R m = 2.58 (6) fm for 8B were obtained. The radial density distribution deduced for 8B exhibits a proton halo structure with the rms halo radius R h = 4.24 (25) fm. A comparison of the deduced experimental radii is displayed with existing experimental and theoretical data. [ABSTRACT FROM AUTHOR]

The structure of the 131Sn nucleus was studied at the Institut Laue-Langevin by prompt-delayed -ray spectroscopy across the 0.3 μs, 23/2-isomeric state at 4670 keV, following cold-neutron-induced fission of 235U and 241Pu targets. New -ray transitions are observed and the results are compared with theoretical calculations performed with the Hybrid Configuration Mixing Model. The latter suggests that the majority of the states can be well-described in terms of couplings between single-hole degrees of freedom and 132Sn core excitations, pointing to a robust neutron shell closure at N = 82. [ABSTRACT FROM AUTHOR]