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We describe deformed N = Z nuclei in a formalism of α-like quartets. Quartets are constructed variationally by resorting to the use of proper intrinsic states. Various types of intrinsic states are introduced which generate different sets of quartets for a given nucleus. Energy spectra are generated via configurationiteraction calculations in the spaces built with these quartets. The approach is applied to 24Mg and 28Si in the sd shell and to 48Cr in the p f shell. In all cases a good description of the low-lying spectra is achieved. As a peculiarity of the approach, a close correspondence is observed between the various sets of quartets employed and the occurrence of well defined band-like structures in the spectra of the systems under study. [ABSTRACT FROM AUTHOR]

In this contribution we study the even-even Sr isotopes considering the influence of particle-hole intruder states. We find that the rapid onset of deformation at A = 98 and onwards can be explained by the crossing of regular and intruder states. We compare the systematics of Sr with the ones of Zr, Pt, and Hg nuclei. [ABSTRACT FROM AUTHOR]

The astrophysical p process unites all processes that have been introduced to explain the abundance of a group of 30 to 35 neutron-deficient nuclei which are referred to as p nuclei. In general, these p processes include large networks of nuclear reactions and a complete understanding of the individual reaction rates is required to describe the abundance of the p nuclei qualitatively and quantitatively. In many cases the involved nuclear reactions are not accessible in the laboratory, either due to their low cross sections or because they involve unstable or exotic isotopes. For those purposes, the motivation of cross-section measurements performed at the University of Cologne is twofold: First, experimentally constrained reaction rates are of direct relevance for nucleosynthesis network calculations. And second, experimental cross-section values are required to test existing theoretical descriptions and to improve their predictive power. In this work, we present the experimental setups and methods that are used to measure nuclear cross-sections at very low sensitivities and we show a detailed overview of proton-and α-induced reactions that have been measured in Cologne in the last decade. [ABSTRACT FROM AUTHOR]

β− decay lifetimes are essential ingredients for r-process yield calculations. In N≈126 r-process waiting point nuclei first-forbidden and allowed β decays are expected to compete. Recent experiments performed at CERN/ISOLDE showed that 207,208Hg decay predominantly via first-forbidden decays. In addition, following on a high statistics study of the β+ /EC decay of 208At, it is suggested that the Z>82, N<126 nuclei provide an excellent testing ground for global calculations addressing the competition between first-forbidden and allowed β decays. [ABSTRACT FROM AUTHOR]

A solution is worked out for a γ-unstable Bohr Hamiltonian with an infinite square well potential having an adjustable step. The evolution of the model's spectral characteristics are investigated with varying height and width of the additional step, revealing shape coexisting an mixing features. The description of the dynamical shape phase transition in the collective bands of the Te even-even nuclei is offered as a numerical application. [ABSTRACT FROM AUTHOR]

We performed a polarized neutron transmission asymmetry measurement utilizing the 139La(n,γ)140La reaction. This measurement involved the use of a recently developed 3He spin filter mounted on the J-PARC MLF beam line number 4 (BL04). The resulting value of the longitudinal asymmetry AL = (11.7 ± 1.1)% was found to be in good agreement with existing values in the literature suggesting that the method by which we polarize the neutron beam is not a significant source of uncertainty. This preliminary work represents a first step toward future measurements of the angular correlation in (n̅,Υ) reactions necessary in the search for enhanced T-Violation in compound nuclei. [ABSTRACT FROM AUTHOR]

The nuclear mean field as a function of momentum and density is the quantity of crucial relevance in the study of nuclear matter and the equation of state can be obtained from it at momentum equals to Fermi momentum. In order to simulate the momentum dependence of the mean field, the effective interaction is constructed in the simplest form and the parameters are fixed with proper care on the momentum dependent aspects of the mean fields in different kinds of nuclear matter. By fixing the parameters of the interaction, as discussed in the work, microscopic trends of nuclear matter properties and predictions in finite nuclei, not less than any other conventional interaction, could be obtained. [ABSTRACT FROM AUTHOR]

The core recoil momentum distribution of neutron-rich isotopes of light exotic nuclei is studied within a three-body model, where the nuclei are described by a core and two neutrons, with interactions dominated by the s-wave channel. In our framework, the two-body subsystems should have large scattering lengths in comparison with the interaction range allowing to use a three-body model with a zero-range force. The ground-state halo wave functions in momentum space are obtained by using as inputs the two-neutron separation energy and the energies of the singlet neutron-neutron and neutron-core virtual states. Within our model, we obtain the momentum probability densities for the Borromean exotic nuclei 11Li and 22C. In the case of the core recoil momentum distribution of 11Li, a fair reproduction of the experimental data was obtained, without free parameters, considering only the two-body low-energies. By analysing the obtained core momentum distribution in face of recent experimental data, we verify that such data are constraining the 22C two-neutron separation energy to a value between 100 and 400 keV. [ABSTRACT FROM AUTHOR]

We study the 11Li and 22C nuclei at leading order (LO) in halo effective field theory (Halo EFT). Using the value of the 22C rms matter radius deduced in Ref. [1] as an input in a LO calculation, we simultaneously constrain the values of the two-neutron (2n) separation energy of 22C and the virtual-state energy of the 20C-neutron system (hereafter denoted 21C). The 1-σ uncertainty of the input rms matter radius datum, along with the theory error estimated from the anticipated size of the higher-order terms in the Halo EFT expansion, gives an upper bound of about 100 keV for the 2n separation energy. We also study the electric dipole excitation of 2n halo nuclei to a continuum state of two neutrons and the core at LO in Halo EFT. We first compare our results with the 11Li data from a Coulomb dissociation experiment and obtain good agreement within the theoretical uncertainty of a LO calculation. We then obtain the low-energy spectrum of B(E1) of this transition at several different values of the 2n separation energy of 22C and the virtual-state energy of 21C. Our predictions can be compared to the outcome of an ongoing experiment on the Coulomb dissociation of 22C to obtain tighter constraints on the two- and three-body energies in the 22C system. [ABSTRACT FROM AUTHOR]

Pairing and quartetting are competing phenomena in nuclei. In the selfconjugate nuclei from the fp-shell, the competition between T=0 pairing (deuteron-like) and alpha clusterisation is predicted to be affected by the spin-orbit interaction. In order to probe the α structure of fp-shell nuclei, the nuclear break-up of 40Ca and 40Ar has been measured at GANIL. The α spectroscopic factors obtained for the N=Z nucleus and the N≠Z nuclei do not reflect any difference. This might be an indication that the tail of the wave function in not sensitive to nuclear asymmetry. Perspectives for probing the deuteron-like pairing (T=0) are given. [ABSTRACT FROM AUTHOR]

The 3He(α, γ)7Be and 3H(α, γ)7Li astrophysical S factors are evaluated at low collision energies (less than 2.5 MeV in the centre-of-mass frame) within the no-core shell model with continuum using a renormalized chiral nucleon-nucleon interaction. [ABSTRACT FROM AUTHOR]

Electron scattering at very high Bjorken x from hadrons provides an excellent test of models, has an important role in high energy physics, and from nuclei, provides a window into short range correlations. Light nuclei have a key role because of the relatively well-known nuclear structure. The development of a novel tritium target for Jefferson Lab has led to renewed interest in the mass three system. For example, deep inelastic scattering experiments in the light nuclei provide a powerful means to determine the neutron structure function. The isospin dependence of electron scattering from mass- 3 nuclei provide information on short range correlations in nuclei. The program using the new tritium target will be presented along with a summary of other experiments aimed at revealing the large-x structure of the nucleon. [ABSTRACT FROM AUTHOR]

Chiral extrapolations of the binding energy of the X(3872) molecular state are investigated using an explicitly renormalizable framework free of finite cut-off artefacts. Insights into the binding mechanisms are discussed: if the X is less bound with the growing pion mass, its binding energy is governed by the explicit pion mass dependence from one-pion exchange; an opposite behaviour would indicate the importance of the pionmass dependent short-range interactions, in addition to pionic effects. The important role of the three-body DDπ dynamics is emphasised. [ABSTRACT FROM AUTHOR]

We briefly review the theory for electromagnetic reactions in light nuclei based on the coupled-cluster formulation of the Lorentz integral transform method. Results on photodisintegration reactions of 22O and 40Ca are reported and preliminary calculations on the Coulomb sum rule for 4He are discussed. [ABSTRACT FROM AUTHOR]

The strong interaction of antikaons (K-) with nucleons and nuclei in the lowenergy regime represents an active research field connected intrinsically with few-body physics. There are important open questions like the question of antikaon nuclear bound states - the prototype system being K-pp. A unique and rather direct experimental access to the antikaon-nucleon scattering lengths is provided by precision X-ray spectroscopy of transitions in low-lying states of light kaonic atoms like kaonic hydrogen isotopes. In the SIDDHARTA experiment at the electron-positron collider DAФNE of LNF-INFN we measured the most precise values of the strong interaction observables, i.e. the strong interaction on the 1s ground state of the electromagnetically bound K-p atom leading to a hadronic shift ϵ1s and a hadronic broadening Γ1s of the 1s state. The SIDDHARTA result triggered new theoretical work which achieved major progress in the understanding of the low-energy strong interaction with strangeness. Antikaon-nucleon scattering lengths have been calculated constrained by the SIDDHARTA data on kaonic hydrogen. For the extraction of the isospin-dependent scattering lengths a measurement of the hadronic shift and width of kaonic deuterium is necessary. Therefore, new X-ray studies with the focus on kaonic deuterium are in preparation (SIDDHARTA2). Many improvements in the experimental setup will allow to measure kaonic deuterium which is challenging due to the anticipated low X-ray yield. Especially important are the data on the X-ray yields of kaonic deuterium extracted from a exploratory experiment within SIDDHARTA. [ABSTRACT FROM AUTHOR]

I discuss the role of relativistic quantum mechanics in few-body physics, various formulations of relativistic few-body quantum mechanics and how they are related. [ABSTRACT FROM AUTHOR]

Many light nuclei display behaviour that indicates that rather than behaving as an A-body systems, the protons and neutrons condense into clusters. The α-particle is the most obvious example of such clustering. This contribution examines the role of such α-clustering on the structure, symmetries and dynamics of the nuclei 8Be, 12C and 16O, recent experimental measurements and future perspectives. [ABSTRACT FROM AUTHOR]

Precise measurement of neutrino oscillations, and hence the determination of their masses demands a quantitative understanding of neutrino-nucleus interactions. To this aim, two-body meson-exchange currents have to be accounted for along within realistic models of nuclear dynamics. We summarize our progresses towards the construction of a consistent framework, based on quantum Monte Carlo methods and on the spectral function approach, that can be exploited to accurately describe neutrino interactions with atomic nuclei over the broad kinematical region covered by neutrino experiments. [ABSTRACT FROM AUTHOR]

The present understanding of nuclear electromagnetic properties including electromagnetic moments, form factors and transitions in nuclei with A ⩽ 10 is reviewed. Emphasis is on calculations based on nuclear Hamiltonians that include two- and threenucleon realistic potentials, along with one- and two-body electromagnetic currents derived from a chiral effective field theory with pions and nucleons. [ABSTRACT FROM AUTHOR]

An ab initio (i.e., from first principles) theoretical framework capable of providing a unified description of the structure and low-energy reaction properties of light nuclei is desirable to further our understanding of the fundamental interactions among nucleons, and provide accurate predictions of crucial reaction rates for nuclear astrophysics, fusion-energy research, and other applications. In this contribution we review ab initio calculations for nucleon and deuterium scattering on light nuclei starting from chiral two- and three-body Hamiltonians, obtained within the framework of the ab initio no-core shell model with continuum. This is a unified approach to nuclear bound and scattering states, in which square-integrable energy eigenstates of the A-nucleon system are coupled to (A-a)+a target-plus-projectile wave functions in the spirit of the resonating group method to obtain an efficient description of the many-body nuclear dynamics both at short and medium distances and at long ranges. [ABSTRACT FROM AUTHOR]

Few-body systems with resonant S-wave interactions show universal properties which are independent of the interaction at short distances. These properties include a geometric spectrum of three- and higher-body bound states and universal correlations between few-body observables. They can be observed on a wide range of scales from hadrons and nuclei to ultracold atoms. In this contribution, we focus on few-body universality in halo nuclei which can be considered as effective few-body systems consisting of halo nucleons and a core. This concept provides a unifying framework for halo nuclei with calculable corrections. Recent progress in this field with an emphasis on the possibility of finding Efimov states in halo nuclei is discussed. [ABSTRACT FROM AUTHOR]

For 43 stable nuclei-targets in a wide interval of mass number 28 ≤ A ≤ 200 the intensities Iγγ of the two-step cascades were measured. The experimental data are interpreted and approximated with a high accuracy within a simple practical model describing two-step γ decay of neutron resonance. [ABSTRACT FROM AUTHOR]

Recent results of the Fayans energy density functional (EDF) for spherical nuclei are reviewed. A comparison is made with predictions of several Skyrme EDFs. The charge radii and characteristics of the first 2+ excitations in semi-magic nuclei are briefly discussed. The single-particle spectra of doubly magic nuclei are considered in more detail. The phonon-particle coupling effects are analyzed including the tadpole term. [ABSTRACT FROM AUTHOR]

Characteristics of the decay of alpha like nuclei produced in various reactions with alpha conjugate nuclei are discussed. We observe a significant number of events in which a large fraction of the system breaks up into alpha-conjugate nuclei. Lighter fragments in the various decay channels appear to originate from a neck-like region between 4 and 7 cm/ns whereas the heavier fragments appear to originate from velocities near the beam velocity. This behavior is consistent with a hierarchy effect that cannot be explained by statistical processes. [ABSTRACT FROM AUTHOR]

In the present study, B(E2; 2+ → 0+) values have been measured in the 208Rn and 206Po nuclei through Coulomb excitation of re-accelerated radioactive beams in inverse kinematics at CERN-ISOLDE. The resulting B(E2; 2+ → 0+) in 208Rn is ~ 0.08 e²b². These nuclei lie in, or at the boundary of the region where seniority scheme should persist. However, contributions from collective excitations may be present when moving away from the N = 126 shell closure. To date, surprisingly little is known of the transition probabilities between the low-spin states in this region. [ABSTRACT FROM AUTHOR]

Limits of stability of nuclear systems are explored within the frame-work of a finite-range interacting Fermi gas model and microcanonical thermodynamics in Thomas-Fermi approximation. It is found that with increasing excitation energy, infinite systems become unstable against volume boiling, while finite systems become subject to surface boiling, providing a natural explanation for the observed saturation-like patterns, or limiting temperature, in caloric curves. Boiling patterns of iso-asymmetric matter are discussed. [ABSTRACT FROM AUTHOR]