We present a fully dynamical simulation of central nuclear collisions around midrapidity at LHC energies. Unlike previous treatments, we simulate all phases of the collision, including the equilibration of the system. For the simulation, we use numerical relativity solutions to anti–de Sitter space/conformal field theory for the preequilibrium stage, viscous hydrodynamics for the plasma equilibrium stage, and kinetic theory for the low-density hadronic stage. Our preequilibrium stage provides initial conditions for hydrodynamics, resulting in sizable radial flow. The resulting light particle spectra reproduce the measurements from the ALICE experiment at all transverse momenta.

The ALICE measurement of $K_S^0$ and $\Lambda$ production at midrapidity in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76\mathrm{TeV}$ is presented. The transverse momentum ($p_T$) spectra are shown for several collision centrality intervals and in the $p_T$ range from $0.4\mathrm{GeV}/c$ ($0.6\mathrm{GeV}/c$ for $\Lambda$) to $12\mathrm{GeV}/c$. The $p_T$ dependence of the $\Lambda /K_S^0$ ratios exhibits maxima in the vicinity of $3\mathrm{GeV}/c$, and the positions of the maxima shift towards higher $p_T$ with increasing collision centrality. The magnitude of these maxima increases by almost a factor of three between most peripheral and most central Pb-Pb collisions. This baryon excess at intermediate $p_T$ is not observed in $pp$ interactions at $\sqrt{s}=0.9\mathrm{TeV}$ and at $\sqrt{s}=7\mathrm{TeV}$. Qualitatively, the baryon enhancement in heavy-ion collisions is expected from radial flow. However, the measured $p_T$ spectra above $2\mathrm{GeV}/c$ progressively decouple from hydrodynamical-model calculations. For higher values of $p_T$, models that incorporate the influence of the medium on the fragmentation and hadronization processes describe qualitatively the $p_T$ dependence of the $\Lambda /K_S^0$ ratio.

The PHENIX collaboration at the Relativistic Heavy Ion Collider (RHIC) reports measurements of azimuthal dihadron correlations near midrapidity in $d+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$. These measurements complement recent analyses by experiments at the Large Hadron Collider (LHC) involving central $p+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$, which have indicated strong anisotropic long-range correlations in angular distributions of hadron pairs. The origin of these anisotropies is currently unknown. Various competing explanations include parton saturation and hydrodynamic flow. We observe qualitatively similar, but larger, anisotropies in $d+\mathrm{Au}$ collisions at RHIC compared to those seen in $p+\mathrm{Pb}$ collisions at the LHC. The larger extracted $v_2$ values in $d+\mathrm{Au}$ are consistent with expectations from hydrodynamic calculations owing to the larger expected initial-state eccentricity compared with that from $p+\mathrm{Pb}$ collisions. When both are divided by an estimate of the initial-state eccentricity the scaled anisotropies follow a common trend with multiplicity that may extend to heavy ion data at RHIC and the LHC, where the anisotropies are widely thought to arise from hydrodynamic flow.

The magnetic moments and isotope shifts of the neutron-deficient francium isotopes ${}^{202\mathrm{\text{−}}205}\mathrm{Fr}$ were measured at ISOLDE-CERN with use of collinear resonance ionization spectroscopy. A production-to-detection efficiency of 1% was measured for ${}^{202}\mathrm{Fr}$. The background from nonresonant and collisional ionization was maintained below one ion in ${10}^5$ beam particles. Through a comparison of the measured charge radii with predictions from the spherical droplet model, it is concluded that the ground-state wave function remains spherical down to ${}^{205}\mathrm{Fr}$, with a departure observed in ${}^{203}\mathrm{Fr}$ ($N=116$).

Neutron-rich $N=22$, 24, 26 magnesium isotopes were studied via in-beam $\gamma$-ray spectroscopy at the RIKEN Radioactive Isotope Beam Factory following secondary fragmentation reactions on a carbon target at $\approx 200\mathrm{MeV}/\mathrm{\text{nucleon}}$. In the one- and two-proton removal channels from ${}^{39}\mathrm{Al}$ and ${}^{40}\mathrm{Si}$ beams, two distinct $\gamma$-ray transitions were observed in ${}^{38}\mathrm{Mg}$, while in the one-proton removal reaction from ${}^{37}\mathrm{Al}$ a new transition was observed in addition to the known $2_1^{+}\to 0_{\mathrm{g}.\mathrm{s}.}^{+}$ decay. From the experimental systematics and comparison to theoretical predictions it is concluded that the transitions belong to the $2_1^{+}\to 0_{\mathrm{g}.\mathrm{s}.}^{+}$ and $4_1^{+}\to 2_1^{+}$ decays in ${}^{36}\mathrm{Mg}$ and ${}^{38}\mathrm{Mg}$, respectively. For ${}^{34}\mathrm{Mg}$, previously reported $2_1^{+}$ and $4_1^{+}$ level energies were remeasured. The deduced $E(4_1^{+})/E(2_1^{+})$ ratios for ${}^{34,36,38}\mathrm{Mg}$ of 3.14(5), 3.07(5), and 3.07(5) are almost identical and suggest the emergence of a large area of deformation extending from the $N=20$ to the $N=28$ shell quenching.

We present possible indications for flavor separation during the QCD crossover transition based on continuum extrapolated lattice QCD calculations of higher order susceptibilities. We base our findings on flavor-specific quantities in the light and strange quark sector. We propose a possible experimental verification of our prediction, based on the measurement of higher order moments of identified particle multiplicities. Since all our calculations are performed at zero baryochemical potential, these results are of particular relevance for the heavy-ion program at the LHC.

We present results for three charmonia states (${\psi }^{\prime }$, ${\chi }_c$, and $J/\psi$) in $d+\mathrm{Au}$ collisions at $|y|<0.35$ and $\sqrt{s_{NN}}=200\mathrm{GeV}$. We find that the modification of the ${\psi }^{\prime }$ yield relative to that of the $J/\psi$ scales approximately with charged particle multiplicity at midrapidity across $p+A$, $d+\mathrm{Au}$, and $A+A$ results from the Super Proton Synchrotron and the Relativistic Heavy Ion Collider. In large-impact-parameter collisions we observe a similar suppression for the ${\psi }^{\prime }$ and $J/\psi$, while in small-impact-parameter collisions the more weakly bound ${\psi }^{\prime }$ is more strongly suppressed. Owing to the short time spent traversing the Au nucleus, the larger ${\psi }^{\prime }$ suppression in central events is not explained by an increase of the nuclear absorption owing to meson formation time effects.

Proton-nucleus collisions ($p+A$) at LHC energies provide a rigorous test of color glass condensate (CGC), a model proposed to describe the high energy limit of quantum chromodynamics. In the CGC the average multiplicity of charged particles at midrapidity in $p+A$ collisions depends logarithmically on the number of participants, $N_{\mathrm{part}}$. In contrast, the wounded nucleon model of independent nucleon-nucleon scatterings, verified at RHIC energies, predicts that multiplicity in $p+A$ depends linearly on $N_{\mathrm{part}}$. We argue that the dependence of mean multiplicity on $N_{\mathrm{part}}$ in $p+A$ collisions at LHC energies can single out a model of particle production, thus offering a stringent test of the CGC and the wounded nucleon model. Based on this observation we propose a novel experimental test of color coherence in $p+A$ collisions.

We study the mass dependence for identified particle average transverse momentum and harmonic flow coefficients in proton-lead ($p$-Pb) collisions, recently measured at the LHC. The collective mechanism in the $p$-Pb system predicts a specific mass ordering in these observables: the growth of the average transverse momentum with the particle mass and a mass splitting of the elliptic flow coefficient, i.e., smaller differential elliptic flow of protons than pions for $p_T<2\mathrm{GeV}$. This provides an opportunity to distinguish between the collective scenario and the mechanism based on the initial gluon dynamics in the evolution of the $p$-Pb system.

The nucleus ${}^{154}\mathrm{Gd}$ is located in a region of the nuclear chart where rapid changes of nuclear deformation occur as a function of particle number. It was investigated using a combination of $\gamma$-ray scattering experiments and a $\gamma \gamma$-coincidence study following electron capture decay of ${}^{154}\mathrm{Tb}^m$. A novel decay channel from the scissors mode to the first excited $0^{+}$ state was observed. Its transition strength was determined to $B(M1;1_{sc}^{+}\to 0_2^{+})=0.031(4){\mu }_N^2$. The properties of the scissors mode of ${}^{154}\mathrm{Gd}$ imply a much larger matrix element than previously thought for the neutrinoless double-$\beta$ decay to the $0_2^{+}$ state in such a shape-transitional region. Theory indicates an even larger effect for ${}^{150}\mathrm{Nd}$.

We present a detailed study of the effect of different three-nucleon interactions in $p$-${}^3\mathrm{He}$ elastic scattering at low energies. In particular, two interactions have been considered: one derived from effective field theory at next-to-next-to-leading order and one derived from a more phenomenological point of view—the so-called Illinois model. The four-nucleon scattering observables are calculated by using the Kohn variational principle and the hyperspherical harmonics technique, and the results are compared with available experimental data. We have found that the inclusion of both interactions improves the agreement with the experimental data, in particular, for the proton vector analyzing power.

The ${\mathcal{D}}_{03}$ dibaryon is generated dynamically as a resonance pole in a $\pi N{\Delta }^{\prime }$ three body model, where ${\Delta }^{\prime }$ is a stable $\Delta$ baryon. Using separable interactions dominated by the $\Delta (1232)$ isobar for $\pi N$ and by the ${\mathcal{D}}_{12}(2150)$ isobar for $N{\Delta }^{\prime }$, with ${\mathcal{D}}_{12}(2150)$ the $N\Delta$ dibaryon deduced in and constrained by ${}^{1}D_2$ $pp$ scattering, the model reduces to an effective two body problem for $\Delta {\Delta }^{\prime }$ which is solved. The mass and width of ${\mathcal{D}}_{03}$ are found close to those of the $I(J^P)=0(3^{+})$ resonance peak observed by WASA-at-COSY in pion-production $pn$ collisions at 2.37 GeV.

The pairing gap for ${}^{53}\mathrm{Ca}$ obtained from new experimental data on the masses of ${}^{52–54}\mathrm{Ca}$ has the smallest value yet observed. This is explained in the framework of the nuclear shell model with schematic and realistic Hamiltonians as being due to shell gaps around the low-$j$ orbital $1p_{1/2}$. Minima in the pairing gaps for all nuclei are shown and discussed.

We report on the first measurement of inclusive $J/\psi$ elliptic flow $v_2$ in heavy-ion collisions at the LHC. The measurement is performed with the ALICE detector in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76\mathrm{TeV}$ in the rapidity range $2.5<y<4.0$. The dependence of the $J/\psi$ $v_2$ on the collision centrality and on the $J/\psi$ transverse momentum is studied in the range $0\le p_T<10\mathrm{GeV}/c$. For semicentral Pb-Pb collisions at $\sqrt{s_{NN}}=2.76\mathrm{TeV}$, an indication of nonzero $v_2$ is observed with a largest measured value of $v_2=0.116\pm 0.046(\mathrm{stat})\pm 0.029(\mathrm{syst})$ for $J/\psi$ in the transverse momentum range $2\le p_T<4\mathrm{GeV}/c$. The elliptic flow measurement complements the previously reported ALICE results on the inclusive $J/\psi$ nuclear modification factor and favors the scenario of a significant fraction of $J/\psi$ production from charm quarks in a deconfined partonic phase.

The Lead Radius Experiment has provided the first model-independent evidence in favor of a neutron-rich skin in ${}^{208}\mathrm{Pb}$. Although the error bars are large, the reported large central value of 0.33 fm is particularly intriguing. To test whether such a thick neutron skin in ${}^{208}\mathrm{Pb}$ is already incompatible with laboratory experiments or astrophysical observations, we employ relativistic models with neutron-skin thickness in ${}^{208}\mathrm{Pb}$ ranging from 0.16 to 0.33 fm to compute ground-state properties of finite nuclei, their collective monopole and dipole response, and mass-versus-radius relations for neutron stars. No compelling reason was found to rule out models with large neutron skins in ${}^{208}\mathrm{Pb}$ from the set of observables considered in this Letter.

Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, $\Delta \varphi$, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the $\Delta \varphi$ dependence of jet yields in $0.14{\mathrm{nb}}^{-1}$ of $\sqrt{s_{NN}}=2.76\mathrm{TeV}$ $\mathrm{Pb}+\mathrm{Pb}$ collisions at the LHC for jet transverse momenta $p_T>45\mathrm{GeV}$ in different collision centrality bins using an underlying event subtraction procedure that accounts for elliptic flow. The variation of the jet yield with $\Delta \varphi$ was characterized by the parameter, $v_2^{\mathrm{jet}}$, and the ratio of out-of-plane ($\Delta \varphi \sim \pi /2$) to in-plane ($\Delta \varphi \sim 0$) yields. Nonzero $v_2^{\mathrm{jet}}$ values were measured in all centrality bins for $p_T<160\mathrm{GeV}$. The jet yields are observed to vary by as much as 20% between in-plane and out-of-plane directions.

The level structures of the very neutron-rich nuclei ${}^{128}\mathrm{Pd}$ and ${}^{126}\mathrm{Pd}$ have been investigated for the first time. In the $r$-process waiting-point nucleus ${}^{128}\mathrm{Pd}$, a new isomer with a half-life of $5.8(8)\mu \mathrm{s}$ is proposed to have a spin and parity of $8^{+}$ and is associated with a maximally aligned configuration arising from the $g_{9/2}$ proton subshell with seniority $\upsilon =2$. For ${}^{126}\mathrm{Pd}$, two new isomers have been identified with half-lives of 0.33(4) and $0.44(3)\mu \mathrm{s}$. The yrast $2^{+}$ energy is much higher in ${}^{128}\mathrm{Pd}$ than in ${}^{126}\mathrm{Pd}$, while the level sequence below the $8^{+}$ isomer in ${}^{128}\mathrm{Pd}$ is similar to that in the $N=82$ isotone ${}^{130}\mathrm{Cd}$. The electric quadrupole transition that depopulates the $8^{+}$ isomer in ${}^{128}\mathrm{Pd}$ is more hindered than the corresponding transition in ${}^{130}\mathrm{Cd}$, as expected in the seniority scheme for a semimagic, spherical nucleus. These experimental findings indicate that the shell closure at the neutron number $N=82$ is fairly robust in the neutron-rich Pd isotopes.

Nuclear matrix elements (NME) for the most promising candidates to detect neutrinoless double beta decay have been computed with energy density functional methods including deformation and pairing fluctuations explicitly on the same footing. The method preserves particle number and angular momentum symmetries and can be applied to any decay without additional fine tunings. The finite range density dependent Gogny force is used in the calculations. An increase of 10%–40% in the NME with respect to the ones found without the inclusion of pairing fluctuations is obtained, reducing the predicted half-lives of these isotopes.

Configuration-space matrix elements of $N$-body potentials arise naturally and ubiquitously in the Ritz-Galerkin solution of many-body quantum problems. For the common specialization of local, finite-range potentials, we develop the exact tensor hypercontraction method, which provides a quantized renormalization of the coordinate-space form of the $N$-body potential, allowing for a highly separable tensor factorization of the configuration-space matrix elements. This representation allows for substantial computational savings in chemical, atomic, and nuclear physics simulations, particularly with respect to difficult “exchangelike” contractions.

A measurement of beam helicity asymmetries in the reaction ${}^3\overrightarrow{\mathrm{He}}(\overrightarrow{e},e^{\prime }n)pp$ is performed at the Mainz Microtron in quasielastic kinematics to determine the electric to magnetic form factor ratio of the neutron $G_E^n/G_M^n$ at a four-momentum transfer $Q^2=1.58{\mathrm{GeV}}^2$. Longitudinally polarized electrons are scattered on a highly polarized ${}^3\mathrm{He}$ gas target. The scattered electrons are detected with a high-resolution magnetic spectrometer, and the ejected neutrons are detected with a dedicated neutron detector composed of scintillator bars. To reduce systematic errors, data are taken for four different target polarization orientations allowing the determination of $G_E^n/G_M^n$ from a double ratio. We find ${\mu }_n{G}_E^n/G_M^n=0.250\pm 0.058(\mathrm{stat})\pm 0.017(\mathrm{syst})$.