The deuteron to proton polarization transfer coefficients $K_{\mathit{yy}}^{y^{\text{'}}}$ and $K_y^{y^{\text{'}}}$ together with the deuteron analyzing powers are measured in three coplanar configurations of the deuteron-proton breakup reaction with a 135-MeV/nucleon polarized deuteron beam at the RIKEN Accelerator Research Facility. The data are compared with theoretical predictions based on exact solutions of the three-nucleon ($3N$) Faddeev equations with high-precision nucleon-nucleon ($\mathit{NN}$) forces, alone or combined with two $3N$ force (3NF) models, the $2\pi$-exchange Tucson-Melbourne${}^{\text{'}}(99)$ (${\mathrm{TM}}^{\text{'}}99$) and Urbana IX. Large 3NF effects have been found for all the measured observables. Predicted effects are supported by the data, with the exception of the vector analyzing power $A_y^d$. For this observable, theory based on only $\mathit{NN}$ forces is sufficient to explain the data. The behavior of the breakup analyzing powers is found to be different from the corresponding observables in elastic nucleon-deuteron scattering.

The two-particle azimuthal angle correlation (TPAC) and azimuthal charge balance function (ACBF) are used to study the anisotropic expansion in relativistic heavy ion collisions. It is demonstrated by the relativistic quantum molecular dynamics (RQMD) model and a multi-phase transport (AMPT) model that the small-angle correlation in TPAC indeed presents anisotropic expansion, and the large-angle (or back-to-back) correlation is mainly due to global momentum conservations. The AMPT model reproduces the observed TPAC, but the RQMD model fails to reproduce the strong correlations in both small and large azimuthal angles. The width of ACBF from RQMD and AMPT models decreases from peripheral to central collisions, consistent with experimental data, but in contrast to the expectation from thermal model calculations. The ACBF is insensitive to anisotropic expansion. It is a probe for the mechanism of hadronization, similar to the charge balance function in rapidity.

Cross sections for $(n,2n)$, $(n,p)$, $(n,n^{\text{'}}\alpha )$, $(n,t)$, $(n,d^{\text{'}})$, and $(n,\alpha )$ reactions have been measured on tantalum isotopes at the neutron energies of 13.5 to 14.7 MeV using the activation technique. Data are reported for the following reactions: ${}^{181}\mathrm{Ta}(n,2n){}^{180}\mathrm{Ta}{}^g$, ${}^{181}\mathrm{Ta}(n,p){}^{181}\mathrm{Hf}$, ${}^{181}\mathrm{Ta}(n,n^{\text{'}}\alpha ){}^{177}\mathrm{Lu}{}^m$, ${}^{181}\mathrm{Ta}(n,t){}^{179}\mathrm{Hf}{}^{m2}$, ${}^{181}\mathrm{Ta}(n,d^{\text{'}}){}^{180}\mathrm{Hf}{}^m$, and ${}^{181}\mathrm{Ta}(n,\alpha ){}^{178}\mathrm{Lu}{}^m$. The neutron fluences were determined using the monitor reaction ${}^{27}\mathrm{Al}(n,\alpha ){}^{24}\mathrm{Na}$. Results were discussed and compared with the previous works.

Excited states of the neutron-deficient nucleus ${}^{175}\mathrm{Hg}$, populated using fusion-evaporation reactions, are reported for the first time. The spin and parity of the ground state has been determined to be $I^{\pi }=7/2^{-}$ through measurements of the $\alpha$ decay to the daughter nucleus ${}^{171}\mathrm{Pt}$. A structure based on an isomeric state [$T_{1/2}=0.34(3)\hspace{0.5em}\mu$s] with $I^{\pi }=13/2^{+}$ and its decay path to the ground state have been established. The observed structures are interpreted in terms of single-particle configurations, and the trends of coexisting shapes in neighboring nuclei are discussed.

The chiral interpretation of negative-parity twin bands in the odd-$A$ ${}^{135}\mathrm{Nd}$ nucleus was investigated in the interacting boson-fermion model. The IBFM calculation shows that the dominant role in the formation of the chiral pattern has the exchange interaction, i.e., the antisymmetrization of odd fermions with the fermion structure of the bosons. The structure of the twin bands in ${}^{137}\mathrm{Nd}$ has also been investigated, concluding that it is determined by shape fluctuations and prolate-oblate coexistence rather than by chirality.

We construct a simple two-phase equation of state intended to resemble that of compressed baryon-rich matter and then introduce a gradient term in the compressional energy density to take account of finite-range effects in nonuniform configurations. With this model we study the interface between the two coexisting phases and obtain estimates for the associated interface tension. Subsequently, we incorporate the finite-range equation of state into ideal or viscous fluid dynamics and derive the collective dispersion relation for the mechanically unstable modes of bulk matter in the spinodal region of the thermodynamic phase diagram. Combining these results with time scales extracted from existing dynamical transport simulations, we discuss the prospects for spinodal phase separation to occur in nuclear collisions. We argue that these can be optimized by a careful tuning of the collision energy to maximize the time spent by the bulk of the system inside the mechanically unstable spinodal region of the phase diagram. Our specific numerical estimates suggest cautious optimism that this phenomenon may in fact occur, though a full dynamical simulation is needed for a detailed assessment.

We relate the three-dimensional infinite momentum frame spatial charge density of the pion to its electromagnetic form factor $F_{\pi }(Q^2)$. Diverse treatments of the measured form factor data including phenomenological fits, nonrelativistic quark models, the application of perturbative quantum chromodynamics (QCD), QCD sum rules, holographic QCD, and the Nambu–Jona-Lasinio (NJL) model all lead to the result that the charge density at the center of the pion has a logarithmic divergence. Relativistic constituent quark models do not display this singularity. Future measurements planned for larger values of $Q^2$ may determine whether or not a singularity actually occurs.

We estimate the nuclear medium modifications of the quark contribution to the bound nucleon spin sum rule, $J^{q^{*}}$, as well the separate helicity, $\Delta {\Sigma }^{*}$, and the angular momentum, $L^{q^{*}}$, contributions to $J^{q^{*}}$. For the calculation of the bound nucleon generalized parton distributions (GPDs), we use as input the bound nucleon elastic form factors predicted in the quark-meson coupling model. Our model for the bound nucleon GPDs is relevant for incoherent deeply virtual Compton scattering (DVCS) with nuclear targets. We find that the medium modifications increase $J^{q^{*}}$ and $L^{q^{*}}$ and decrease $\Delta {\Sigma }^{*}$ compared to the free nucleon case. The effect is large and increases with increasing nuclear density ρ. For instance, at $\rho ={\rho }_0=0.15\hspace{0.5em}{\mathrm{fm}}^{-3},J^{q^{*}}$ increases by 7%, $L^{q^{*}}$ increases by 20%, and $\Delta {\Sigma }^{*}$ decreases by 17%. These in-medium modifications of the bound nucleon spin properties are a general feature of relativistic mean-field quark models and may be understood qualitatively in terms of the enhancement of the lower component of the quark Dirac spinor in the nuclear medium.

A self-consistent calculation of nuclear matrix elements of the neutrinoless double-beta decays ($0\nu \beta \beta$) of ${}^{76}\mathrm{Ge}$, ${}^{82}\mathrm{Se}$, ${}^{96}\mathrm{Zr}$, ${}^{100}\mathrm{Mo}$, ${}^{116}\mathrm{Cd}$, ${}^{128}\mathrm{Te}$, ${}^{130}\mathrm{Te}$, and ${}^{136}\mathrm{Xe}$ is presented in the framework of the renormalized quasiparticle random phase approximation (RQRPA) and the standard QRPA. The pairing and residual interactions as well as the two-nucleon short-range correlations are for the first time derived from the same modern realistic nucleon-nucleon potentials, namely, from the charge-dependent Bonn potential (CD-Bonn) and the Argonne V18 potential. In a comparison with the traditional approach of using the Miller-Spencer Jastrow correlations, matrix elements for the $0\nu \beta \beta$ decay are obtained that are larger in magnitude. We analyze the differences among various two-nucleon correlations including those of the unitary correlation operator method (UCOM) and quantify the uncertainties in the calculated $0\nu \beta \beta$-decay matrix elements.

A new critical survey is presented of all half-life, decay-energy, and branching-ratio measurements related to 20 superallowed $0^{+}\to 0^{+}\beta$ decays. Compared with our last review, there are numerous improvements: First, we have added 27 recently published measurements and eliminated 9 references, either because they have been superseded by much more precise modern results or because there are now reasons to consider them fatally flawed; of particular importance, the new data include a number of high-precision Penning-trap measurements of decay energies. Second, we have used the recently improved isospin symmetry-breaking corrections, which were motivated by these new Penning-trap results. Third, our calculation of the statistical rate function $f$ now accounts for possible excitation in the daughter atom, a small effect but one that merits inclusion at the present level of experimental precision. Finally, we have re-examined the systematic uncertainty associated with the isospin symmetry-breaking corrections by evaluating the radial-overlap correction using Hartree-Fock radial wave functions and comparing the results with our earlier calculations, which used Saxon-Woods wave functions; the provision for systematic uncertainty has been changed as a consequence. The new “corrected” $\mathcal{F}t$ values are impressively constant and their average, when combined with the muon lifetime, yields the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, $V_{\mathit{ud}}=0.97425\pm 0.00022$. The unitarity test on the top row of the matrix becomes $\left|V_{\mathit{ud}}\right|{}^2+\left|V_{\mathit{us}}\right|{}^2+\left|V_{\mathit{ub}}\right|{}^2=0.99995\pm 0.00061$. Both $V_{\mathit{ud}}$ and the unitarity sum have significantly reduced uncertainties compared with our previous survey, although the new value of $V_{\mathit{ud}}$ is statistically consistent with the old one. From these data we also set limits on the possible existence of scalar interactions, right-hand currents, and extra $Z$ bosons. Finally, we discuss the priorities for future theoretical and experimental work with the goal of making the CKM unitarity test even more definitive.

We have investigated the photoneutron reactions on the isotopes ${}^{192}\mathrm{Os}$ and ${}^{191,193}\mathrm{Ir}$ for astrophysically relevant photon energies just above the neutron separation energy. The experiments were performed using the photoactivation technique at the superconducting Darmstadt linear electron accelerator (S-DALINAC). The measurements extend the existing experimental database on photoneutron reactions in this mass region and serve as an important test for the state-of-the-art statistical model calculations commonly used for the prediction of stellar reaction rates.

The recently developed chiral nucleon-nucleon ($\mathit{NN}$) potential by E. Epelbaum, W. Glöckle, and Ulf-G. Meißner, Nucl. Phys. A747, 362 (2005) has been employed to study the two-nucleon bound and scattering states. Chiral $\mathit{NN}$ potential up to next-to-next-to-next-to leading order ($\mathrm{N}{}^3\mathrm{LO}$) is used to calculate the $\mathit{np}$ differential cross section and deuteron binding energy in a realistic three dimensional approach. The obtained results based on this helicity representation are compared to the standard partial wave (PW) results. This comparison shows that the 3D approach provides the same accuracy in the description of $\mathit{NN}$ observables and the results are in close agreement with available experimental data.

We explore neutron skin predictions for ${}^{208}\mathrm{Pb}$ in relation to the symmetry pressure in various microscopic models based on realistic nucleon-nucleon potentials and either the Dirac-Brueckner-Hartree-Fock approach or the conventional Brueckner-Hartree-Fock framework implemented with three-body forces. We also discuss the correlation between the neutron skin and the radius of a fixed-mass neutron star.

Neutron hole states in the exotic $N=27$ isotope ${}^{44}\mathrm{Cl}$ have been populated using the intermediate-energy single-neutron knockout reaction ${}^9\mathrm{Be}({}^{45}\mathrm{Cl},{}^{44}\mathrm{Cl})\mathrm{X}$. The momentum distribution of the residual ${}^{44}\mathrm{Cl}$ nuclei after direct population of the ground state is consistent with removal of an $l=1$ neutron. This observation and comparison with a shell-model calculation imply that $p_{3/2}$ neutrons from above the $N=28$ major shell closure play important roles in the ground states of both ${}^{44}\mathrm{Cl}$ and ${}^{45}\mathrm{Cl}$. The present result is significant because ${}^{44}\mathrm{Cl}$ is even closer to the valley of stability than ${}^{43}\mathrm{S}$, where a similar result was recently obtained using a $g$-factor measurement.

Evaporation residues and fission excitation functions obtained in complete fusion reactions leading to Po compound nuclei have been analyzed in the framework of the standard statistical model. Macroscopic fission barriers deduced from the cross-section data analysis are compared with the predictions of various theoretical models and available data. A drop in the Po barriers with the decrease in a neutron number was found, which is stronger than predicted by any theory. The presence of entrance channel effects and collective excitations in the compound nucleus decay is considered as a possible reason for the barrier reduction.

Sets of simple relations for evaluation of the half-lives of α transitions between the ground states of parent and daughter nuclei are presented. Experimental data for half-lives in 344 α emitters are used for obtaining the sets of equations. The sets of simple expressions are found for the whole data set as well as for heavy and light subsets of nuclei. Terms related to the orbital moment and parity of α transition are introduced for the case of α decay in even-odd, odd-even, and odd-odd nuclei. The electron screening effect is taken into account.

We calculate transverse momentum distribution of direct photons from various sources by taking into account the initial state momentum anisotropy of quark-gluon plasma (QGP) and late stage transverse flow effects. To evaluate the photon yield from hadronic matter we include the contributions from baryon-meson reactions. The total photon yield, calculated for various combinations of initial conditions and transition temperatures, is then compared with the recent measurement of photon transverse momentum distribution by the PHENIX Collaboration. It is shown that because of the initial state anisotropy the photon yield from the QGP is larger by a factor of 8–10 than that of the isotropic case in the intermediate $p_T$ regime. It is also demonstrated that the presence of such an anisotropy can describe the PHENIX photon data better than the isotropic case in the present model. We show that the isotropization time thus extracted lies within the range $1.5⩾{\tau }_{\mathrm{iso}}⩾0.5$ fm/$c$ for the initial conditions used here.

Using the ground-state energy of ${}^{16}\mathrm{O}$ obtained with the realistic $V_{\mathrm{UCOM}}$ interaction as a test case, we present a comprehensive comparison of different configuration interaction (CI) and coupled-cluster (CC) methods, analyzing the intrinsic advantages and limitations of each of the approaches. In particular, we use the importance-truncated (IT) CI and no-core shell model (NCSM) schemes with up to 4-particle-4-hole (4p4h) excitations, with and without the Davidson extensivity corrections, as well as the size extensive CC methods with a complete treatment of one- and two-body clusters (CCSD) and a noniterative treatment of connected three-body clusters via the completely renormalized correction to the CCSD energy defining the CR-CC(2,3) approach, which are all capable of handling larger systems with dozens of explicitly correlated fermions. We discuss the impact of the center-of-mass contaminations, the choice of the single-particle basis, and size-extensivity on the resulting energies. When the IT-CI and IT-NCSM methods include the 4p4h excitations and when the CC calculations include the 1p1h, 2p2h, and 3p3h clusters, as in the CR-CC(2,3) approach, we observe an excellent agreement among the different methodologies, particularly when the Davidson extensivity corrections are added to the IT-CI energies and the effects of the connected three-body clusters are accounted for in the CC calculations. This shows that despite their individual limitations, the IT-CI, IT-NCSM, and CC methods can provide precise and consistent ab initio nuclear structure predictions. Furthermore, the IT-CI, IT-NCSM, and CC ground-state energy values obtained for ${}^{16}\mathrm{O}$ are in reasonable agreement with the experimental value, providing further evidence that the $V_{\mathrm{UCOM}}$ two-body interaction may allow for a good description of binding energies for heavier nuclei and that all of the methods used in this study account for most of the relevant particle correlation effects.

177 neutron spectroscopic factors for nickel isotopes have been extracted by performing a systematic analysis of the angular distributions measured from ($d,p$) transfer reactions. A subset of the extracted spectroscopic factors are compared to predictions of large-basis shell models in the full $\mathit{pf}$ model space using the GXPF1A effective interaction, and the $(f_{5/2},p_{3/2},p_{1/2},g_{9/2})$ model space using the JJ4PNA interaction. For ground states, the predicted spectroscopic factors using the GXPF1A effective interaction in the full $\mathit{pf}$ model space agree very well with the experimental values, while predictions based on several other effective interactions and model spaces are about 30% higher than the experimental values. For low-energy excited states ($<3.5$ MeV), the agreement between the extracted spectroscopic factors and shell model calculations is not better than a factor of two.

The ($p,p\alpha$) reaction on ${}^{12}\mathrm{C}$ was investigated experimentally using polarized incident protons of 100 MeV. The scattered proton and $\alpha$ particle, from the knockout reaction, were detected in coincidence. Coincident data, which were obtained at ten quasifree angle pairs for proton angles ranging from ${25}^{°}$ to ${110}^{°}$, were analyzed in terms of the distorted-wave impulse approximation (DWIA). Calculated energy-sharing cross section and analyzing power distributions reproduce the data reasonably well, indicating that a quasifree knockout mechanism dominates the reaction. Since measurements of analyzing powers were made, spin-orbit distortions were included in the DWIA calculations. The effects of this were found to be very small near zero recoil momentum and did not destroy the validity of the factorization approximation where the two-body $p\text{−}\alpha$ cross section enters as a multiplicative factor in the three-body ($p,p\alpha$) cross section expression. Spectroscopic factors derived from the data are consistent with theoretical predictions. Analyzing power data also follow the trend of free $p\text{−}{}^4\mathrm{He}$ scattering data, and comparisons with DWIA predictions are in reasonable agreement. Because the two-body interaction response between the projectile and the $\alpha$ cluster was found to resemble the scattering of protons from a free $\alpha$ particle to a remarkable degree, the present results would strongly imply the existence of preformed $\alpha$ clusters in ${}^{12}\mathrm{C}$.