The yield of charged particles associated with high-$p_t$ trigger particles ($8<p_t<15\mathrm{GeV}/\mathrm{c}$) is measured with the ALICE detector in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76\mathrm{TeV}$ relative to proton-proton collisions at the same energy. The conditional per-trigger yields are extracted from the narrow jetlike correlation peaks in azimuthal dihadron correlations. In the 5% most central collisions, we observe that the yield of associated charged particles with transverse momenta $p_t>3\mathrm{GeV}/\mathrm{c}$ on the away side drops to about 60% of that observed in $pp$ collisions, while on the near side a moderate enhancement of 20%–30% is found.

We present new measurements of electron scattering from high-momentum nucleons in nuclei. These data allow an improved determination of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data also include the kinematic region where three-nucleon correlations are expected to dominate.

Stimulated by recent experimental discoveries, triaxial strongly deformed (TSD) states in ${}^{158}\mathrm{Er}$ at ultrahigh spins have been studied by means of the Skyrme-Hartree-Fock model and the tilted-axis-cranking method. Restricting the rotational axis to one of the principal axes—as done in previous cranking calculations—two well-defined TSD minima in the total Routhian surface are found for a given configuration: one with positive and another with negative triaxial deformation $\gamma$. By allowing the rotational axis to change direction, the higher-energy minimum is shown to be a saddle point. This resolves the long-standing question of the physical interpretation of the two triaxial minima at a very similar quadrupole shape obtained in the principal-axis-cranking approach. Several TSD configurations have been predicted, including a highly deformed band, which is a candidate for the structure observed in experiment.

We report transverse momentum ($p_T\le 15\mathrm{GeV}/c$) spectra of ${\pi }^{\pm }$, $K^{\pm }$, $p$, $\overline{p}$, $K_S^0$, and ${\rho }^0$ at midrapidity in $p+p$ and $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$. Perturbative QCD calculations are consistent with ${\pi }^{\pm }$ spectra in $p+p$ collisions but do not reproduce $K$ and $p(\overline{p})$ spectra. The observed decreasing antiparticle-to-particle ratios with increasing $p_T$ provide experimental evidence for varying quark and gluon jet contributions to high-$p_T$ hadron yields. The relative hadron abundances in $\mathrm{Au}+\mathrm{Au}$ at $p_T\gtrsim 8\mathrm{GeV}/c$ are measured to be similar to the $p+p$ results, despite the expected Casimir effect for parton energy loss.

We report new STAR measurements of midrapidity yields for the $\Lambda$, $\overline{\Lambda }$, $K_S^0$, ${\Xi }^{-}$, ${\overline{\Xi }}^{+}$, ${\Omega }^{-}$, ${\overline{\Omega }}^{+}$ particles in $\mathrm{Cu}+\mathrm{Cu}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$, and midrapidity yields for the $\Lambda$, $\overline{\Lambda }$, $K_S^0$ particles in $\mathrm{Au}+\mathrm{Au}$ at $\sqrt{s_{NN}}=200\mathrm{GeV}$. We show that, at a given number of participating nucleons, the production of strange hadrons is higher in $\mathrm{Cu}+\mathrm{Cu}$ collisions than in $\mathrm{Au}+\mathrm{Au}$ collisions at the same center-of-mass energy. We find that aspects of the enhancement factors for all particles can be described by a parametrization based on the fraction of participants that undergo multiple collisions.

The ${}^{110}\mathrm{Pd}$ double-$\beta$ decay $Q$ value was measured with the Penning-trap mass spectrometer ISOLTRAP to be $Q=2017.85(64)\mathrm{keV}$. This value shifted by 14 keV compared with the literature value and is 17 times more precise, resulting in new phase-space factors for the two-neutrino and neutrinoless decay modes. In addition a new set of the relevant matrix elements has been calculated. The expected half-life of the two-neutrino mode was reevaluated as $1.5(6)\times {10}^{20}\mathrm{yr}$. With its high natural abundance, the new results reveal ${}^{110}\mathrm{Pd}$ to be an excellent candidate for double-$\beta$ decay studies.

The neutron-rich nuclei ${}^{94,96}\mathrm{Kr}$ were studied via projectile Coulomb excitation at the REX-ISOLDE facility at CERN. Level energies of the first excited $2^{+}$ states and their absolute $E2$ transition strengths to the ground state are determined and discussed in the context of the $E(2_1^{+})$ and $B(E2;2_1^{+}\to 0_1^{+})$ systematics of the krypton chain. Contrary to previously published results no sudden onset of deformation is observed. This experimental result is supported by a new proton-neutron interacting boson model calculation based on the constrained Hartree-Fock-Bogoliubov approach using the microscopic Gogny-D1M energy density functional.

In-medium binding energies and Mott points for $d$, $t$, ${}^3\mathrm{He}$ and $\alpha$ clusters in low-density nuclear matter have been determined at specific combinations of temperature and density in low-density nuclear matter produced in collisions of $47A$ MeV ${}^{40}\mathrm{Ar}$ and ${}^{64}\mathrm{Zn}$ projectiles with ${}^{112}\mathrm{Sn}$ and ${}^{124}\mathrm{Sn}$ target nuclei. The experimentally derived values of the in-medium modified binding energies are in good agreement with recent theoretical predictions based upon the implementation of Pauli blocking effects in a quantum statistical approach.

${}^{209}\mathrm{Bi}$ alpha decay to the ground and to the first excited state have been recently observed for the first time with a large BGO scintillating bolometer. The half-life of ${}^{209}\mathrm{Bi}$ is determined to be ${\tau }_{1/2}=(2.01\pm 0.08)\times {10}^{19}\mathrm{yr}$ while the branching ratio for the ground-state to ground-state transition is $(98.8\pm 0.3)\%$.

It has long been recognized that the observation of $\gamma$ rays originating from nuclear deexcitation can be exploited to identify neutral-current neutrino-nucleus interactions in water-Cherenkov detectors. We report the results of a calculation of the neutrino- and antineutrino-induced $\gamma$-ray production cross section for the oxygen target. Our analysis is focused on the kinematical region of neutrino energy larger than $\sim 200\mathrm{MeV}$, in which a single-nucleon knockout is known to be the dominant reaction mechanism. The numerical results have been obtained using for the first time a realistic model of the target spectral function, extensively tested against electron-nucleus scattering data. We find that at a neutrino energy of 600 MeV the fraction of neutral-current interactions leading to emission of $\gamma$ rays of energy larger than 6 MeV is $\sim 41\%$, and that the contribution of the $p_{3/2}$ state is overwhelming.

The parameters in the macroscopic droplet part of the finite-range droplet model (FRDM) are related to the properties of the equation of state. In the FRDM (1992) version, the optimization of the model parameters was not sufficiently sensitive to variations of the compressibility constant $K$ and the density-symmetry constant $L$ to allow their determination. In the new, more accurate FRDM-2011a adjustment of the model constants to new and more accurate experimental masses allows the determination of $L$ together with the symmetry-energy constant $J$. The optimization is still not sensitive to $K$ which is therefore fixed at $K=240\mathrm{MeV}$. Our results are $J=32.5\pm 0.5\mathrm{MeV}$ and $L=70\pm 15\mathrm{MeV}$ and a considerably improved mass-model accuracy $\sigma =0.5700\mathrm{MeV}$, with respect to the 2003 Atomic Mass Evaluation (AME2003) for FRDM-2011a, compared to $\sigma =0.669\mathrm{MeV}$ for FRDM (1992).

The muon-capture reactions ${}^2\mathrm{H}({\mu }^{-},{\nu }_{\mu })nn$ and ${}^3\mathrm{He}({\mu }^{-},{\nu }_{\mu }){}^3\mathrm{H}$ are studied with nuclear potentials and charge-changing weak currents, derived in chiral effective field theory. The low-energy constants (LECs) $c_D$ and $c_E$, present in the three-nucleon potential and ($c_D$) axial-vector current, are constrained to reproduce the $A=3$ binding energies and the triton Gamow-Teller matrix element. The muon-capture rates on deuteron and ${}^3\mathrm{He}$ are predicted to be $399\pm 3{\sec }^{-1}$ and $1494\pm 21{\sec }^{-1}$, respectively. The spread accounts for the cutoff sensitivity, as well as uncertainties in the LECs and electroweak radiative corrections. By comparing the calculated and precisely measured rates on ${}^3\mathrm{He}$, a value for the induced pseudoscalar form factor is obtained in good agreement with the chiral perturbation theory prediction.

We perform the first quantitative analysis of the reaction cross sections of ${}^{28–32}\mathrm{Ne}$ by ${}^{12}\mathrm{C}$ at $240\mathrm{MeV}/\mathrm{nucleon}$, using the double-folding model with the Melbourne $g$ matrix and the deformed projectile density calculated by antisymmetrized molecular dynamics. To describe the tail of the last neutron of ${}^{31}\mathrm{Ne}$, we adopt the resonating group method combined with antisymmetrized molecular dynamics. The theoretical prediction excellently reproduces the measured cross sections of ${}^{28–32}\mathrm{Ne}$ with no adjustable parameters. The ground state properties of ${}^{31}\mathrm{Ne}$, i.e., strong deformation and a halo structure with spin parity $3/2^{-}$, are clarified.

The first direct mass measurement of ${}^6\mathrm{He}$ has been performed with the TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the mass of ${}^8\mathrm{He}$ was determined with improved precision over our previous measurement. The obtained masses are $m({}^6\mathrm{He})=6.018885883(57)\mathrm{u}$ and $m({}^8\mathrm{He})=8.03393444(11)\mathrm{u}$. The ${}^6\mathrm{He}$ value shows a deviation from the literature of $4\sigma$. With these new mass values and the previously measured atomic isotope shifts we obtain charge radii of 2.060(8) and 1.959(16) fm for ${}^6\mathrm{He}$ and ${}^8\mathrm{He}$, respectively. We present a detailed comparison to nuclear theory for ${}^6\mathrm{He}$, including new hyperspherical harmonics results. A correlation plot of the point-proton radius with the two-neutron separation energy demonstrates clearly the importance of three-nucleon forces.

Charge radii of all magnesium isotopes in the $sd$ shell have been measured, revealing evolution of the nuclear shape throughout two prominent regions of assumed deformation centered on ${}^{24}\mathrm{Mg}$ and ${}^{32}\mathrm{Mg}$. A striking correspondence is found between the nuclear charge radius and the neutron shell structure. The importance of cluster configurations towards $N=8$ and collectivity near $N=20$ is discussed in the framework of the fermionic molecular dynamics model. These essential results have been made possible by the first application of laser-induced nuclear orientation for isotope shift measurements.

We present a Pfaffian formula for projection and symmetry restoration for wave functions of the general Bogoliubov form, including quasiparticle excited states and linear combinations of them. This solves a long-standing problem in calculating states of good symmetry, arising from the sign ambiguity of the commonly used determinant formula. A simple example is given of projecting a good particle number and angular momentum from a Bogoliubov wave function in the Fock space of a single $j$-shell.

The two-body photodisintegration cross section of ${}^4\mathrm{He}$ into a proton and triton was measured with monoenergetic photon beams in 0.5 MeV energy steps between 22 and 30 MeV. High-pressure ${}^4\mathrm{He}\mathrm{\text{−}}\mathrm{Xe}$ gas scintillators of various ${}^4\mathrm{He}/\mathrm{Xe}$ ratios served as targets and detectors. Pure Xe gas scintillators were used for background studies. A NaI detector together with a plastic scintillator paddle was employed for determining the incident photon flux. Our comprehensive data set follows the trend of the theoretical calculations of the Trento group very well, although our data are consistently lower in magnitude by about 5%. However, they differ significantly from the majority of the previous data, especially from the recent data of Shima et al. The latter data had put into question the validity of theoretical approaches used to calculate core-collapse supernova explosions and big-bang nucleosynthesis abundances of certain light nuclei.

Evidence for the neutron-rich hypernucleus ${}_{\Lambda }{}^6\mathrm{H}$ is presented from the FINUDA experiment at $\mathrm{DA}\Phi \mathrm{NE}$, Frascati, studying $({\pi }^{+},{\pi }^{-})$ pairs in coincidence from the $K_{\mathrm{stop}}^{-}+{}^6\mathrm{Li}\to {}_{\Lambda }{}^6\mathrm{H}+{\pi }^{+}$ production reaction followed by ${}_{\Lambda }{}^6\mathrm{H}\to {}^6\mathrm{He}+{\pi }^{-}$ weak decay. The production rate of ${}_{\Lambda }{}^6\mathrm{H}$ undergoing this two-body ${\pi }^{-}$ decay is determined to be $(2.9\pm 2.0)\times {10}^{-6}/K_{\mathrm{stop}}^{-}$. Its binding energy, evaluated jointly from production and decay, is $B_{\Lambda }({}_{\Lambda }{}^6\mathrm{H})=(4.0\pm 1.1)\mathrm{MeV}$ with respect to ${}^5\mathrm{H}+\Lambda$. A systematic difference of $(0.98\pm 0.74)\mathrm{MeV}$ between $B_{\Lambda }$ values derived separately from decay and from production is tentatively assigned to the ${}_{\Lambda }{}^6\mathrm{H}$ $0_{\mathrm{g}.\mathrm{s}.}^{+}\to 1^{+}$ excitation.

We apply the ab initio no-core shell model combined with the resonating-group method approach to calculate the cross sections of the ${}^3\mathrm{H}(d,n){}^4\mathrm{He}$ and ${}^3\mathrm{He}(d,p){}^4\mathrm{He}$ fusion reactions. These are important reactions for the big bang nucleosynthesis and the future of energy generation on Earth. Starting from a selected similarity-transformed chiral nucleon-nucleon interaction that accurately describes two-nucleon data, we performed many-body calculations that predict the $S$ factor of both reactions. Virtual three-body breakup effects are obtained by including excited pseudostates of the deuteron in the calculation. Our results are in satisfactory agreement with experimental data and pave the way for microscopic investigations of polarization and electron-screening effects, of the ${}^3\mathrm{H}(d,\gamma n){}^4\mathrm{He}$ bremsstrahlung and other reactions relevant to fusion research.

The technique of invariant mass spectroscopy has been used to measure, for the first time, the ground state energy of neutron-unbound ${}^{28}\mathrm{F}$, determined to be a resonance in the ${}^{27}\mathrm{F}+n$ continuum at $2\underline{2}0(\underline{5}0)\mathrm{keV}$. States in ${}^{28}\mathrm{F}$ were populated by the reactions of a $62\mathrm{MeV}/\mathrm{u}$ ${}^{29}\mathrm{Ne}$ beam impinging on a $288\mathrm{mg}/{\mathrm{cm}}^2$ beryllium target. The measured ${}^{28}\mathrm{F}$ ground state energy is in good agreement with USDA/USDB shell model predictions, indicating that $pf$ shell intruder configurations play only a small role in the ground state structure of ${}^{28}\mathrm{F}$ and establishing a low-$Z$ boundary of the island of inversion for $N=19$ isotones.