We searched for the bound state of the neutron-rich $\mathrm{\Lambda }$-hypernucleus ${}_{\mathrm{\Lambda }}{}^6\mathrm{H}$, using the ${}^6\mathrm{Li}({\pi }^{-},K^{+})X$ double charge-exchange reaction at a ${\pi }^{-}$ beam momentum of $1.2\mathrm{GeV}/c$ at J-PARC. A total of $1.4\times {10}^{12}{\pi }^{-}$ was driven onto a ${}^6\mathrm{Li}$ target of 3.5-$\mathrm{g}/{\mathrm{cm}}^2$ thickness. No event was observed below the bound threshold, i.e., the mass of ${}_{\mathrm{\Lambda }}{}^4\mathrm{H}+2n$, in the missing-mass spectrum of the ${}^6\mathrm{Li}({\pi }^{-},K^{+})X$ reaction in the $2^{\circ }<{\theta }_{\pi K}<{20}^{\circ }$ angular range. Furthermore, no event was found up to $2.8\mathrm{MeV}/c^2$ above the bound threshold. We obtained the double-differential cross section spectra of the ${}^6\mathrm{Li}({\pi }^{-},K^{+})X$ reaction in the angular range of $2^{\circ }<{\theta }_{\pi K}<{14}^{\circ }$. An upper limit of 0.56 nb/sr (90% C.L.) was obtained for the production cross section of the ${}_{\mathrm{\Lambda }}{}^6\mathrm{H}$ hypernucleus bound state. In addition, not only the bound state region, but also the $\mathrm{\Lambda }$ continuum region and part of the ${\mathrm{\Sigma }}^{-}$ quasifree production region of the ${}^6\mathrm{Li}({\pi }^{-},K^{+}$) reaction were obtained with high statistics. The present missing-mass spectrum will facilitate the investigation of the ${\mathrm{\Sigma }}^{-}$-nucleus optical potential for ${\mathrm{\Sigma }}^{-}-{}^5\mathrm{He}$ through spectrum shape analysis.

The $g$ factor of the first $2^{+}$ state of radioactive ${}^{136}\mathrm{Te}$ with two valence protons and two valence neutrons beyond double-magic ${}^{132}\mathrm{Sn}$ has been measured by the recoil in vacuum (RIV) method. The lifetime of this state is an order of magnitude longer than the lifetimes of excited states recently measured by the RIV method in Sn and Te isotopes, requiring a new evaluation of the free-ion hyperfine interactions and methodology used to determine the $g$ factor. The calibration data are reported and the analysis procedures are described in detail. The resultant $g$ factor has a similar magnitude to the $g$ factors of other nuclei with an equal number of valence protons and neutrons in the major shell. However, an unexpected trend is found in the $g$ factors of the $N=84$ isotones, which decrease from ${}^{136}\mathrm{Te}$ to ${}^{144}\mathrm{Nd}$. Shell model calculations with interactions derived from the CD Bonn potential show good agreement with the $g$ factors and $E2$ transition rates of $2^{+}$ states around ${}^{132}\mathrm{Sn}$, confirming earlier indications that ${}^{132}\mathrm{Sn}$ is a good doubly magic core.

An extension of the atomic mass surface in the region $A\approx 100$ was performed via measurements of the ${}^{100-102}\mathrm{Sr}$ and ${}^{100-102}\mathrm{Rb}$ masses with the ion-trap spectrometer ISOLTRAP at CERN-ISOLDE, including the first direct mass determination of ${}^{102}\mathrm{Sr}$ and ${}^{101,102}\mathrm{Rb}$. These measurements confirm the continuation of the region of deformation with the increase of neutron number, at least as far as $N=65$. To interpret the deformation in the strontium isotopic chain and to determine whether an onset of deformation is present in heavier krypton isotopes, a comparison is made between the experimental values and mean-field and beyond mean-field results available in the literature. To complete this comparison Hartree-Fock-Bogoliubov calculations for even and odd isotopes were performed, illustrating the competition of nuclear shapes in the region.

Predictions and comparisons of hadronic flow observables for Pb+Pb collisions at 2.76 and 5.02 TeV are presented using a hydrodynamics + hadronic cascade hybrid approach. Initial conditions are generated via a new formulation of the IP-Glasma model and then evolved using relativistic viscous hydrodynamics and finally fed into transport cascade in the hadronic phase. The results of this work show excellent agreement with the recent charged hadron anisotropic flow measurements from the ALICE Collaboration of Pb+Pb collisions at 5.02 TeV. Event-by-event distributions of charged hadron $v_n$, flow event-plane correlations, and flow factorization breaking ratios are compared with existing measurements at 2.76 TeV, and are predicted at 5.02 TeV. Further predictions of identified hadron observables (for both light and multistrange hadrons), such as $p_T$-spectra and anisotropic flow coefficients, are presented.

We report on the calculation of Gamow-Teller and double-$\beta$ decay properties for nuclei around ${}^{132}\mathrm{Sn}$ within the framework of the realistic shell model. The effective shell-model Hamiltonian and Gamow-Teller transition operator are derived by way of many-body perturbation theory, without resorting to the empirical effective quenching factor for the Gamow-Teller operator. The results are then compared with the available experimental data, in order to establish the reliability of our approach. This is a mandatory step before we apply the same methodology, in forthcoming studies, to the calculation of the neutrinoless double-$\beta$ decay nuclear matrix elements for nuclei that are currently considered among the best candidates for the detection of this process.

Measurement of $M$, the total multiplicity, for central collision between comparable mass heavy ions can provide a signature for first-order phase transition. The derivative of $M$ with respect to $E^{*}/A$, where $E^{*}$ is the excitation energy in the center of mass and $A$ is the total mass of the dissociating system, is expected to go through maximum as a function of $E^{*}$. Theoretical modeling shows that this is the energy where the specific heat $C_v$ maximizes, which typically happens at the first-order phase transition. The measurement of total $M$ is probably feasible in more than one laboratory.

Yrast and near-yrast levels up to spin values in excess of $I=30\hslash$ have been delineated in the doubly magic ${}^{208}\mathrm{Pb}$ nucleus following deep-inelastic reactions involving ${}^{208}\mathrm{Pb}$ targets and, mostly, 430-MeV ${}^{48}\mathrm{Ca}$ and 1440-MeV ${}^{208}\mathrm{Pb}$ beams. The level scheme was established up to an excitation energy of 16.4 MeV, based on multifold γ-ray coincidence relationships measured with the Gammasphere array. Below the well-known, 0.5-μs ${10}^{+}$ isomer, ten new transitions were added to earlier work. The delineation of the higher parts of the level sequence benefited from analyses involving a number of prompt- and delayed-coincidence conditions. Three new isomeric states were established along the yrast line with $I^{\pi }={20}^{-}$ (10 342 keV), ${23}^{+}$ (11 361 keV), and ${28}^{-}$ (13 675 keV), and respective half-lives of 22(3), 12.7(2), and 60(6) ns. Gamma transitions were also identified preceding in time the ${28}^{-}$ isomer; however, only a few could be placed in the level scheme and no firm spin-parity quantum numbers could be proposed. In contrast, for most states below this ${28}^{-}$ isomer, firm spin-parity values were assigned, based on total electron-conversion coefficients, deduced for low-energy $(<500\mathrm{keV})$ transitions from γ-intensity balances, and on measured γ-ray angular distributions. The latter also enabled the quantitative determination of mixing ratios. The transition probabilities extracted for all isomeric transitions in ${}^{208}\mathrm{Pb}$ have been reviewed and discussed in terms of the intrinsic structure of the initial and final levels involved. Particular emphasis was placed on the many observed $E3$ transitions as they often exhibit significant enhancements in strength [of the order of tens of Weisskopf units (W.u.)] comparable to the one seen for the neutron ${\mathrm{j}}_{15/2}\to {\mathrm{g}}_{9/2}$ $E3$ transition in ${}^{209}\mathrm{Pb}$. In this context, the enhancement of the 725-keV $E3$ transition (56 W.u.) associated with the decay of the highest-lying ${28}^{-}$ isomer observed in this work remains particularly challenging to explain. Large-scale shell-model calculations were performed with two approaches, a first one where the 1, 2, and 3 particle-hole excitations do not mix with one another, and another more complex one, in which such mixing takes place. The calculated levels were compared with the data and a general agreement is observed for most of the ${}^{208}\mathrm{Pb}$ level scheme. At the highest spins and energies, however, the correspondence between theory and experiment is less satisfactory and the experimental yrast line appears to be more regular than the calculated one. This regularity is notable when the level energies are plotted versus the $I(I+1)$ product and the observed, nearly linear, behavior was considered within a simple “rotational” interpretation. Within this approximate picture, the extracted moment of inertia suggests that only the 76 valence nucleons participate in the “rotation” and that the ${}^{132}\mathrm{Sn}$ spherical core remains inert.

We study the nuclear modifications of full jets and their structures in relativistic heavy-ion collisions, including the effect of hydrodynamic medium response to jet quenching. To study the evolutions of the full jet shower and the traversed medium with energy and momentum exchanges between them, we formulate a coupled jet-fluid model consisting of a set of jet transport equations and relativistic hydrodynamics equations with source terms. In our model, the full jet shower interacts with the medium and gets modified via collisional and radiative processes during the propagation. Meanwhile, the energy and momentum are deposited from the jet shower to the medium and then evolve with the medium hydrodynamically. The full jet defined by a cone size in the final state includes the jet shower and the particles produced from jet-induced flow. We apply our model to calculate the full jet energy loss and the nuclear modifications of jet rate and shape in Pb+Pb collisions at $2.76A\mathrm{TeV}$. It is found that the inclusion of jet-induced flow contribution leads to stronger jet-cone size dependence for jet energy loss and jet suppression. Jet-induced flow also has a significant contribution to jet shape function and dominates at large angles away from the jet axis.

Recent measurements at the Large Hadron Collider involve the correlation of different azimuthal flow harmonics $v_n$. These new observables add constraints to theoretical models and probe aspects of the system that are independent of traditional single-harmonic measurements such as two-particle and multiparticle cumulants $v_n\left\{m\right\}$. Many of these new observables have not yet been measured at the Relativistic Heavy Ion Collider (RHIC), leaving an opportunity to make predictions as a test of models across energies. We make predictions using NeXSPheRIO, a hydrodynamical model which has accurately reproduced a large set of single-harmonic correlations in a large range of transverse momenta and centralities at RHIC. Our predictions thus provide an important baseline for comparison to correlations of flow harmonics, which contain nontrivial information about the initial state as well as quark-gluon plasma transport properties. We also point out significant biases that can appear when using wide centrality bins and nontrivial event weighting, necessitating care in performing experimental analyses and in comparing theoretical calculations to these measurements.

By combining microscopically calculated level densities with the Metropolis walk method, we develop a consistent framework for treating the energy and angular-momentum dependence of the nuclear shape evolution in the fission process. For each nucleus under consideration, the level density is calculated microscopically for each of more than five million shapes with a recently developed combinatorial method. The method employs the same single-particle levels as those used for the extraction of the pairing and shell contributions to the macroscopic-microscopic potential-energy surface. Containing no new parameters, the treatment is suitable for elucidating the energy dependence of the dynamics of warm nuclei on pairing and shell effects. It is illustrated for the fission fragment mass distribution for several uranium and plutonium isotopes of particular interest.

We show that observations of the core temperature of transiently accreting neutron stars combined with observations of an accretion outburst give a lower limit to the neutron star core heat capacity. For the neutron stars in the low mass x-ray binaries KS 1731-260, MXB 1659-29, and XTE J1701-462, we show that the lower limit is a factor of a few below the core heat capacity expected if neutrons and protons in the core are paired, so that electrons provide the dominant contribution to the heat capacity. This limit rules out a core dominated by a quark color-flavor-locked phase, which would have a much lower heat capacity. Future observations of or limits on cooling during quiescence will further constrain the core heat capacity.

The $Q_{\text{EC}}$ value of the superallowed ${\beta }^{+}$ emitter ${}^{42}\mathrm{Sc}$ has been measured with the JYFLTRAP Penning-trap mass spectrometer at the University of Jyväskylä to be 6426.350(53) keV. This result is at least a factor of four more precise than all previous measurements, which were also inconsistent with one another. As a byproduct we determine the excitation energy of the $7^{+}$ isomeric state in ${}^{42}\mathrm{Sc}$ to be 616.771(62) keV, which deviates by $8\sigma$ from the previous measurement.

The deformation parameters $(\beta ,\gamma )$ together with two-quasiparticle excitations are taken into account, for the first time, as coordinates within a symmetry conserving (angular momentum and particle number) generator coordinate method. The simultaneous consideration of collective as well as single-particle degrees of freedom allows us to describe soft and rigid nuclei as well as the transition region in between. We apply the new theory to the study of the spectra and transition probabilities of the ${}^{156–172}\mathrm{Er}$ isotopes with a pairing-plus-quadrupole residual interaction. Good agreement with the experimental results is obtained for most of the observables studied and with the same quality for the very soft and the strongly deformed nuclei.

Background: Symmetries are a powerful way to characterize nuclear wave functions. A true dynamical symmetry, where the Hamiltonian is block-diagonal in subspaces defined by the group, is rare. More likely is a quasidynamical symmetry: states with different quantum numbers (i.e., angular momentum) nonetheless sharing similar group-theoretical decompositions.

Purpose: We use group-theoretical decomposition to investigate backbending, an abrupt change in the moment of inertia along the yrast line, in ${}^{48,49,50}\mathrm{Cr}$: prior mean-field calculations of these nuclides suggest a change from strongly prolate to more spherical configurations as one crosses the backbending and increases in angular momentum.

Methods: We decompose configuration-interaction shell-model wave functions using the SU(2) groups $L$ (total orbital angular momentum) and $S$ (total spin), and the groups SU(3) and SU(4). We do not need a special basis but only matrix elements of Casimir operators, applied with a modified Lanczos algorithm.

Results: We find quasidynamical symmetries, albeit often of a different character above and below the backbending, for each group. While the strongest evolution was in SU(3), the decompositions did not suggest a decrease in deformation. We point out with a simple example that mean-field and SU(3) configurations may give very different pictures of deformation.

Conclusions: Persistent quasidynamical symmetries for several groups allow us to identify the members of a band and to characterize how they evolve with increasing angular momentum, especially before and after backbending.

Background: The possible existence of a phase transition to a ferromagnetic state in neutron matter as origin of the extremely high magnetic fields of neutron stars is still an open issue. Whereas many phenomenological interactions predict this transition at densities accessible in neutron stars, microscopic calculations based on realistic interactions show no indication of it. The existence or non-existence of this transition is a consequence of the different role of nucleon-nucleon correlations in polarized and unpolarized neutron matter. Therefore, to give a definite answer to this issue it is necessary to analyze the behavior of these correlations.

Purpose: Using the Hellmann–Feynman theorem we analyze the contribution of the different terms of the nucleon-nucleon interaction to the spin symmetry energy of neutron matter with the purpose of identifying the nature and role of correlations in polarized and unpolarized neutron matter.

Methods: The analysis is performed within the microscopic Brueckner–Hartree–Fock approach using the Argonne V18 realistic potential plus the Urbana IX three-body force.

Results: Our results show no indication of a ferromagnetic transition as the spin symmetry energy of neutron matter is always an increasing function of density. They show also that the main contribution to it comes from the $S=0$ channel, acting only in non-polarized neutron matter, in particular from the ${}^1{S}_0$ and the ${}^1{D}_2$ partial waves. Three-body forces are found to play a secondary role in the determination of the spin symmetry energy.

Conclusions: By evaluating the kinetic energy difference between the correlated system and the underlying Fermi sea to estimate the importance of correlations in spin-polarized neutron matter, we conclude that non-polarized neutron matter is more correlated than totally polarized one.

Background: In the context of the investigation of the quark gluon plasma produced in heavy-ion collisions, hadrons containing heavy (charm or beauty) quarks play a special role for the characterization of the hot and dense medium created in the interaction. The measurement of the production of charm and beauty hadrons in proton–proton collisions, besides providing the necessary reference for the studies in heavy-ion reactions, constitutes an important test of perturbative quantum chromodynamics (pQCD) calculations. Heavy-flavor production in proton–nucleus collisions is sensitive to the various effects related to the presence of nuclei in the colliding system, commonly denoted cold-nuclear-matter effects. Most of these effects are expected to modify open-charm production at low transverse momenta $\left(p_{\mathrm{T}}\right)$ and, so far, no measurement of $D$-meson production down to zero transverse momentum was available at mid-rapidity at the energies attained at the CERN Large Hadron Collider (LHC).

Purpose: The measurements of the production cross sections of promptly produced charmed mesons in $p$-Pb collisions at the LHC down to $p_{\mathrm{T}}=0$ and the comparison to the results from $pp$ interactions are aimed at the assessment of cold-nuclear-matter effects on open-charm production, which is crucial for the interpretation of the results from Pb-Pb collisions.

Methods: The prompt charmed mesons $D^0,D^{+},D^{*+}$, and $D_s^{+}$ were measured at mid-rapidity in $p$-Pb collisions at a center-of-mass energy per nucleon pair $\sqrt{s_{NN}}=5.02$ TeV with the ALICE detector at the LHC. $D$ mesons were reconstructed from their decays $D^0\to K^{-}{\pi }^{+},D^{+}\to K^{-}{\pi }^{+}{\pi }^{+}, D^{*+}\to D^0{\pi }^{+},D_s^{+}\to \varphi {\pi }^{+}\to K^{-}{K}^{+}{\pi }^{+}$, and their charge conjugates, using an analysis method based on the selection of decay topologies displaced from the interaction vertex. In addition, the prompt $D^0$ production cross section was measured in $pp$ collisions at $\sqrt{s}=7$ TeV and $p$-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV down to $p_{\mathrm{T}}=0$ using an analysis technique that is based on the estimation and subtraction of the combinatorial background, without reconstruction of the $D^0$ decay vertex.

Results: The production cross section in $pp$ collisions is described within uncertainties by different implementations of pQCD calculations down to $p_{\mathrm{T}}=0$. This allowed also a determination of the total $c\overline{c}$ production cross section in $pp$ collisions, which is more precise than previous ALICE measurements because it is not affected by uncertainties owing to the extrapolation to $p_{\mathrm{T}}=0$. The nuclear modification factor $R_{p\mathrm{Pb}}\left(p_{\mathrm{T}}\right)$, defined as the ratio of the $p_{\mathrm{T}}$-differential $D$ meson cross section in $p$-Pb collisions and that in $pp$ collisions scaled by the mass number of the Pb nucleus, was calculated for the four $D$-meson species and found to be compatible with unity within uncertainties. The results are compared to theoretical calculations that include cold-nuclear-matter effects and to transport model calculations incorporating the interactions of charm quarks with an expanding deconfined medium.

Conclusions: These measurements add experimental evidence that the modification of the $D$-meson transverse momentum distributions observed in Pb–Pb collisions with respect to $pp$ interactions is due to strong final-state effects induced by the interactions of the charm quarks with the hot and dense partonic medium created in ultrarelativistic heavy-ion collisions. The current precision of the measurement does not allow us to draw conclusions on the role of the different cold-nuclear-matter effects and on the possible presence of additional hot-medium effects in $p\text{-Pb}$ collisions. However, the analysis technique without decay-vertex reconstruction, applied on future larger data samples, should provide access to the physics-rich range down to $p_{\mathrm{T}}=0$.

We reexamine the deuteron elastic breakup cross sections on ${}^{12}\mathrm{C}$ and ${}^{10}\mathrm{Be}$ at low incident energies, for which a serious discrepancy between the continuum-discretized coupled-channels (CDCC) method and the Faddeev-Alt-Grassberger-Sandhas (FAGS) theory was pointed out. We show the closed channels neglected in the preceding study affect significantly the breakup cross section calculated with the CDCC method, resulting in good agreement with the result of FAGS theory.

Background: The ${}^{22}\mathrm{Ne}(p,\gamma ){}^{23}\mathrm{Na}$ reaction is the most uncertain process in the neon-sodium cycle of hydrogen burning. At temperatures relevant for nucleosynthesis in asymptotic giant branch stars and classical novae, its uncertainty is mainly due to a large number of predicted but hitherto unobserved resonances at low energy.

Purpose: A new direct study of low-energy ${}^{22}\mathrm{Ne}(p,\gamma ){}^{23}\mathrm{Na}$ resonances has been performed at the Laboratory for Underground Nuclear Astrophysics (LUNA), in the Gran Sasso National Laboratory, Italy.

Method: The proton capture on ${}^{22}\mathrm{Ne}$ was investigated in direct kinematics, delivering an intense proton beam to a ${}^{22}\mathrm{Ne}$ gas target. $\gamma$ rays were detected with two high-purity germanium detectors enclosed in a copper and lead shield suppressing environmental radioactivity.

Results: Three resonances at 156.2 keV [$\omega \gamma =(1.48\pm 0.10)\times {10}^{-7}$ eV], 189.5 keV [$\omega \gamma =(1.87\pm 0.06)\times {10}^{-6}$ eV] and 259.7 keV [$\omega \gamma =(6.89\pm 0.16)\times {10}^{-6}$ eV] proton beam energy, respectively, have been observed for the first time. For the levels at $E_{\mathrm{x}}=8943.5$, 8975.3, and 9042.4 keV excitation energy corresponding to the new resonances, the $\gamma$-decay branching ratios have been precisely measured. Three additional, tentative resonances at 71, 105, and 215 keV proton beam energy, respectively, were not observed here. For the strengths of these resonances, experimental upper limits have been derived that are significantly more stringent than the upper limits reported in the literature.

Conclusions: Based on the present experimental data and also previous literature data, an updated thermonuclear reaction rate is provided in tabular and parametric form. The new reaction rate is significantly higher than previous evaluations at temperatures of 0.08–0.3 GK.

Background: Competing interpretations of the results of a ${}^{30}\mathrm{Mg}$($t,p$)${}^{32}\mathrm{Mg}$ measurement populating the ground state and $0_2^{+}$ state in ${}^{32}\mathrm{Mg}$, both limited to a two-state mixing description, have left an open question regarding the nature of the ${}^{32}\mathrm{Mg}$ ground state.

Purpose: Inspired by recent shell-model calculations, we explore the possibility of a consistent interpretation of the available data for the low-lying $0^{+}$ states in ${}^{32}\mathrm{Mg}$ by expanding the description from two-level to three-level mixing.

Methods: A phenomenological three-level mixing model of unperturbed 0p0h, 2p2h, and 4p4h states is applied to describe both the excitation energies in ${}^{32}\mathrm{Mg}$ and the transfer reaction cross sections.

Results: Within this approach, self-consistent solutions exist that provide good agreement with the available experimental information obtained from the ${}^{30}\mathrm{Mg}$($t,p$)${}^{32}\mathrm{Mg}$ reaction.

Conclusion: The inclusion of the third state, namely the 4p4h configuration, resolves the “puzzle” that results from a two-levelmodel interpretation of the same data. In our analysis, the ${}^{32}\mathrm{Mg}$ ground state emerges naturally as dominated by intruder (2p2h and 4p4h) configurations, at the 95% level.

A quantitative description of the change in ground-state neutron occupancies between ${}^{136}\mathrm{Xe}$ and ${}^{136}\mathrm{Ba}$, the initial and final state in the neutrinoless double-$\beta$ decay of ${}^{136}\mathrm{Xe}$, has been extracted from precision measurements of the cross sections of single-neutron-adding and -removing reactions. Comparisons are made to recent theoretical calculations of the same properties using various nuclear-structure models. These are the same calculations used to determine the magnitude of the nuclear matrix elements for the process, which at present disagree with each other by factors of 2 or 3. The experimental neutron occupancies show some disagreement with the theoretical calculations.