The van der Waals interaction is implemented in a hadron resonance gas model. It is shown that this model can describe lattice QCD data of different thermodynamical quantities satisfactorily with the van der Waals parameters $a=1250\pm 150$ MeV ${\mathrm{fm}}^3$ and $r=0.7\pm 0.05$ fm. Further, a liquid-gas phase transition is observed in this model with the critical point at temperature, $T=62.1$ MeV and baryon chemical potential, ${\mu }_B=708$ MeV.

We systematically measured the differential cross sections of inelastic $\alpha$ scattering off self-conjugate $A=4n$ nuclei at two incident energies $E_{\alpha }=130\mathrm{MeV}$ and $386\mathrm{MeV}$ at Research Center for Nuclear Physics, Osaka University. The measured cross sections were analyzed by the distorted-wave Born-approximation (DWBA) calculation using the single-folding potentials, which are obtained by folding macroscopic transition densities with the phenomenological $\alpha N$ interaction. The DWBA calculation with the density-dependent $\alpha N$ interaction systematically overestimates the cross sections for the $\mathrm{\Delta }L=0$ transitions. However, the DWBA calculation using the density-independent $\alpha N$ interaction reasonably well describes all the transitions with $\mathrm{\Delta }L=0$–4. We examined uncertainties in the present DWBA calculation stemming from the macroscopic transition densities, distorting potentials, phenomenological $\alpha N$ interaction, and coupled channel effects in ${}^{12}\mathrm{C}$. It was found that the DWBA calculation is not sensitive to details of the transition densities nor the distorting potentials, and the phenomenological density-independent $\alpha N$ interaction gives reasonable results. The coupled-channel effects are negligibly small for the $2_1^{+}$ and $3_1^{-}$ states in ${}^{12}\mathrm{C}$, but not for the $0_2^{+}$ state. However, the DWBA calculation using the density-independent interaction at $E_{\alpha }=386\mathrm{MeV}$ is still reasonable even for the $0_2^{+}$ state. We concluded that the macroscopic DWBA calculations using the density-independent interaction are reliably applicable to the analysis of inelastic $\alpha$ scattering at $E_{\alpha }\sim 100\mathrm{MeV}/\mathrm{u}$.

Often mass-dependent nuclear observables are summarized by fits to a power law in the nuclear mass $A$, as proportional to $A^{\alpha }$. In this work a simple justification of this usage is presented, also providing a simple expression for the exponent $\alpha$, with one known parameter being the beam-nucleon total cross section and another parameter being a nuclear size $r_0{A}^{1/3}$. Measured power-law exponents $\alpha$ for total and reaction cross sections are near this simple formulation using $r_0=1.6\mathrm{fm}$, whereas quasifree observables are near the simple expression using $r_0=1.2\mathrm{fm}$.

The ${}^{14}\mathrm{N}(p,\gamma ){}^{15}\mathrm{O}$ reaction is the slowest reaction of the carbon-nitrogen cycle of hydrogen burning and thus determines its rate. The precise knowledge of its rate is required to correctly model hydrogen burning in asymptotic giant branch stars. In addition, it is a necessary ingredient for a possible solution of the solar abundance problem by using the solar ${}^{13}\mathrm{N}$ and ${}^{15}\mathrm{O}$ neutrino fluxes as probes of the carbon and nitrogen abundances in the solar core. After the downward revision of its cross section due to a much lower contribution by one particular transition, capture to the ground state in ${}^{15}\mathrm{O}$, the evaluated total uncertainty is still 8%, in part due to an unsatisfactory knowledge of the excitation function over a wide energy range. The present work reports precise $S$ factor data at twelve energies between 0.357 and 1.292 MeV for the strongest transition, capture to the 6.79-MeV excited state in ${}^{15}\mathrm{O}$, and at ten energies between 0.479 and 1.202 MeV for the second strongest transition, capture to the ground state in ${}^{15}\mathrm{O}$. An $R$-matrix fit is performed to estimate the impact of the new data on astrophysical energies. The recently suggested slight enhancement of the 6.79-MeV transition at low energy could not be confirmed. The present extrapolated zero-energy $S$ factors are $S_{6.79}\left(0\right)=1.24\pm 0.11$ keV b and $S_{\mathrm{GS}}\left(0\right)=0.19\pm 0.05$ keV b.

Background: Type I x-ray bursts are the most frequently observed thermonuclear explosions in the galaxy, resulting from thermonuclear runaway on the surface of an accreting neutron star. The ${}^{30}\mathrm{S}(\alpha ,p)$ reaction plays a critical role in burst models, yet insufficient experimental information is available to calculate a reliable, precise rate for this reaction.

Purpose: Our measurement was conducted to search for states in ${}^{34}\mathrm{Ar}$ and determine their quantum properties. In particular, natural-parity states with large $\alpha$-decay partial widths should dominate the stellar reaction rate.

Method: We performed the first measurement of ${}^{30}\mathrm{S}+\alpha$ resonant elastic scattering up to a center-of-mass energy of 5.5 MeV using a radioactive ion beam. The experiment utilized a thick gaseous active target system and silicon detector array in inverse kinematics.

Results: We obtained an excitation function for ${}^{30}\mathrm{S}(\alpha ,\alpha )$ near ${150}^{\circ }$ in the center-of-mass frame. The experimental data were analyzed with $R$-matrix calculations, and we observed three new resonant patterns between 11.1 and 12.1 MeV, extracting their properties of resonance energy, widths, spin, and parity.

Conclusions: We calculated the resonant thermonuclear reaction rate of ${}^{30}\mathrm{S}(\alpha ,p)$ based on all available experimental data of ${}^{34}\mathrm{Ar}$ and found an upper limit about one order of magnitude larger than a rate determined using a statistical model. The astrophysical impact of these two rates has been investigated through one-zone postprocessing type I x-ray burst calculations. We find that our new upper limit for the ${}^{30}\mathrm{S}(\alpha ,p){}^{33}\mathrm{Cl}$ rate significantly affects the predicted nuclear energy generation rate during the burst.

Differential cross sections at $t=t_{\text{min}}$ and decay asymmetries for the $\gamma p\to \varphi p$ reaction have been measured using linearly polarized photons in the range 1.5 to 2.9 GeV. These cross sections were used to determine the Pomeron strength factor. The cross sections and decay asymmetries are consistently described by the $t$-channel Pomeron and pseudoscalar exchange model in the $E_{\gamma }$ region above 2.37 GeV. In the lower energy region, an excess over the model prediction is observed in the energy dependence of the differential cross sections at $t=t_{\text{min}}$. This observation suggests that additional processes or interference effects between Pomeron exchange and other processes appear near the threshold region.

Background: The nuclear spectral function is a fundamental quantity that describes the mean-field and short-range correlation dynamics of nucleons embedded in the nuclear medium; its knowledge is a prerequisite for the interpretation of various electroweak scattering processes off nuclear targets aimed at providing fundamental information on strong and weak interactions. Whereas in the case of the three-nucleon and, partly, the four-nucleon systems, the spectral function can be calculated ab initio within a nonrelativistic many-body Schroedinger approach, in the case of complex nuclei only models of the correlated, high-momentum part of the spectral function are available so far.

Purpose: The purpose of this paper is to present a new approach such that the spectral function for a specific nucleus can be obtained from a reliable many-body calculation based upon realistic nucleon-nucleon interactions, thus avoiding approximations leading to adjustable parameters.

Methods: The expectation value of the nuclear many-body Hamiltonian, containing realistic nucleon-nucleon interaction of the Argonne family, is evaluated variationally by a normalization-conserving linked-cluster expansion and the resulting many-body correlated wave functions are used to calculate the one-nucleon and the two-nucleon momentum distributions; by analyzing the high-momentum behavior of the latter, the spectral function can be expressed in terms of a transparent convolution formula involving the relative and center-of-mass (c.m.) momentum distributions in specific regions of removal energy $E$ and momentum $k$.

Results: It is found that as a consequence of the factorization of the many-body wave functions at short internucleon separations, the high-momentum behavior of the two-nucleon momentum distributions in $A=3,4,12,16,40$ nuclei factorizes, at proper values of the relative and c.m. momenta, into the c.m. and relative momentum distributions, with the latter exhibiting a universal $A$-independent character. By exploiting the factorization property, it is found that the correlated part of the spectral function can be expressed in terms of a convolution formula depending upon the many-body relative and c.m. momentum distributions of a nucleon pair.

Conclusions: The obtained convolution spectral function of the three-nucleon systems, featuring both two-and three-nucleon short-range correlations, perfectly agrees in a wide range of momentum and removal energy with the ab initio spectral function, whereas in the case of complex nuclei the integral of the obtained spectral functions (the momentum sum rule) reproduces with high accuracy the high-momentum part of the one-nucleon momentum distribution, obtained independently from the Fourier transform of the nondiagonal one-body density matrix. Thus, the convolution spectral function we have obtained appears to indeed be a realistic microscopic, parameter-free quantity governed by the features of the underlying two-nucleon interactions.

Multinucleon transfer reactions near barrier energies have been investigated with a multistep model based on the dinuclear system (DNS) concept, in which the capture of two colliding nuclei, the transfer dynamics, and the deexcitation process of primary fragments are described by an analytical formula, diffusion theory, and a statistical model, respectively. The nucleon transfer takes place after forming the DNS and is coupled to the dissipation of relative motion energy and angular momentum by solving a set of microscopically derived master equations within the potential energy surface. Specific reactions of ${}^{40,48}\mathrm{Ca}+{}^{124}\mathrm{Sn}, {}^{40}\mathrm{Ca}({}^{40}\mathrm{Ar},{}^{58}\mathrm{Ni})+{}^{232}\mathrm{Th}, {}^{40}\mathrm{Ca}\left({}^{58}\mathrm{Ni}\right)+{}^{238}\mathrm{U}$, and ${}^{40,48}\mathrm{Ca}\left({}^{58}\mathrm{Ni}\right)+{}^{248}\mathrm{Cm}$ near barrier energies are investigated. It is found that fragments are produced by multinucleon transfer reactions with maximal yields along the $\beta$-stability line. The isospin relaxation is particularly significant in the process of fragment formation. The incident energy dependence of heavy target-like fragments in the reaction of ${}^{58}\mathrm{Ni}+{}^{248}\mathrm{Cm}$ is analyzed thoroughly.

The discovery of pulsars PSR J1614–2230 and PSR J0348+0432 with masses of around $2M_{\odot }$ imposes strong constraints on the equations of state of cold, ultradense matter. If a phase transition from hadronic matter to quark matter were to occur in the inner cores of such massive neutron stars, the energetically favorable state of quark matter would be a color superconductor. In this study, we analyze the stability and maximum mass of such neutron stars. The hadronic phase is described by nonlinear relativistic mean-field models, and the local Nambu-Jona Lasinio model is used to describe quark matter in the 2SC+s quark phase. The phase transition is treated as a Maxwell transition, assuming a sharp hadron-quark interface, and the “constant-sound-speed” (CSS) parametrization is employed to discuss the existence of stellar twin configurations. We find that massive neutron stars such as J1614-2230 and J0348+0432 can only exist on the connected stellar branch but not on the disconnected twin-star branch. The latter can only support stars with masses that are strictly below $2M_{\odot }$.

The event-by-event fission model $\mathtt{FREYA}$ has been improved, in particular to address deficiencies in the calculation of photon observables. We discuss the improvements that have been made and introduce several new variables, some detector dependent, that affect the photon observables. We show the sensitivity of $\mathtt{FREYA}$ to these variables. We then compare the results to the available photon data from spontaneous and thermal neutron-induced fission.

Background: Low-energy multinucleon transfer reactions may be used for production of new neutron-enriched heavy nuclei.

Purpose: Our aim is to investigate the influence of proton ($Z=82$) and neutron ($N=82$, 126) shells as well as orientation effects on the formation of reaction products in the inverse quasifission process in the reactions ${}^{156,160}\mathrm{Gd}+{}^{186}\mathrm{W}$.

Methods: Mass, energy, and angular distributions of primary binary fragments formed in the reactions ${}^{156}\mathrm{Gd}+{}^{186}\mathrm{W}$ at an energy of 878 MeV, and ${}^{160}\mathrm{Gd}+{}^{186}\mathrm{W}$ at 860 and 935 MeV, have been measured using the double-arm time-of-flight spectrometer CORSET at the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions (FLNR) at the Joint Institute for Nuclear Research (JINR), Dubna.

Results: Enhancement in the yield of products with masses 200–215 u has been found for both reactions. The cross sections of the formation of trans-target fragments with masses around 208 u are found to be about 10 μb at the Coulomb barrier energy and reach the level of 0.5 mb at the energy above the barrier for side-to-side collision.

Conclusions: The enhanced yield of products with masses heavier than the target mass confirms the important role of the closed shells at $Z=82$ and $N=82$, 126 in the inverse quasifission process in low-energy damped collisions. The orientation effect caused by the strong deformation of colliding nuclei can result in a gain in the yield of heavy target-like fragments.

We present a study on the applicability of transverse mass scaling for identified particle spectra in proton-proton collisions at $\sqrt{s}=7$ TeV based on data taken by the ALICE experiment at the LHC. The measured yields are parametrized and compared to estimates obtained from a generalized transverse mass scaling approach applied to different reference particle spectra. It is found that generalized transverse mass scaling is not able to describe the measured spectra over the full range in transverse momentum. At low $p_{\text{T}}$, deviations of $20\%$ or more are obtained, in particular, if pions are used as reference particles. A better scaling performance is obtained when kaons are used as reference particles. At high $p_{\text{T}}$ all tested spectra with the possible exception of the charged kaons exhibit a scaling behavior. Investigating the feed-down contributions from resonance decays to the charged pion yields reveals, that using them as reference a general scaling may not be achievable. Our findings imply that for precision measurements of direct photon and di-electron spectra at low transverse momentum one should measure the relevant hadronic background, instead of relying on $m_{\text{T}}$ scaling for its estimate.

The double-polarization observable $E$ was studied for the reaction $\gamma p\to p\omega$ using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at the Thomas Jefferson National Accelerator Facility and the longitudinally polarized frozen-spin target (FROST). The observable was measured from the charged decay mode of the meson, $\omega \to {\pi }^{+}{\pi }^{-}{\pi }^0$, using a circularly polarized tagged-photon beam with energies ranging from the $\omega$ threshold at 1.1 to 2.3 GeV. A partial-wave analysis within the Bonn-Gatchina framework found dominant contributions from the $3/2^{+}$ partial wave near threshold, which is identified with the subthreshold $N\left(1720\right)3/2^{+}$ nucleon resonance. To describe the entire data set, which consisted of $\omega$ differential cross sections and a large variety of polarization observables, further contributions from other nucleon resonances were found to be necessary. With respect to nonresonant mechanisms, $\pi$ exchange in the $t$ channel was found to remain small across the analyzed energy range, while Pomeron $t$-channel exchange gradually grew from the reaction threshold to dominate all other contributions above $W\approx 2$ GeV.

In this paper, we calculate the properties of two-neutrino double-$\beta$ ($2\nu \beta \beta$) decays for nuclei within $fpg$ ($1p_{3/2},0f_{5/2},1p_{1/2},0g_{9/2}$) shell model space systematically under the framework of the nuclear shell model. Both of the decays on the ${\beta }^{-}$ side ($2\nu 2{\beta }^{-}$) and the mixed ${\beta }^{+}$ and electron capture types ($2\nu 2{\beta }^{+},2\nu {\beta }^{+}\mathrm{EC}$, and $2\nu \mathrm{ECEC}$) are taken into consideration. Results of the calculated half lives, nuclear matrix elements (NMEs), phase space factors, and branching ratios are shown. Good agreements between theory and experiments have been reached. Accumulations of the NMEs are also analyzed which do not support the single-state dominance hypothesis. The half lives of the nuclei ${}^{86}\mathrm{Kr},{}^{70}\mathrm{Zn}$, and ${}^{84}\mathrm{Sr}$ are predicted to be $4.2\times {10}^{22},1.4\times {10}^{23}$, and $1.9\times {10}^{23}$ years respectively which appears attractive for future experimental probing.

The double differential spectra $d^2\sigma /d\mathrm{\Omega }dE$ of $p$, $d$, $t$, ${}^{3,4,6}\mathrm{He}$, ${}^{6,7,8,9}\mathrm{Li}$, ${}^{7,9,10}\mathrm{Be}$, and ${}^{10,11,12}\mathrm{B}$ were measured at seven scattering angles, ${15.6}^{\circ }$, ${20}^{\circ }$, ${35}^{\circ }$, ${50}^{\circ }$, ${65}^{\circ }$, ${80}^{\circ }$, and ${100}^{\circ }$, in the laboratory system for proton induced reactions on a silver target. Measurements were done for three proton energies: 1.2, 1.9, and 2.5 GeV. The experimental data were compared to calculations performed by means of two-step theoretical microscopic models. The first step of the reaction was described by the intranuclear cascade model incl4.6 and the second one by four different models (ABLA07, GEM2, gemini++, and SMM) using their standard parameter settings. Systematic deviations of the data from predictions of the models were observed. The deviations were especially large for the forward scattering angles and for the kinetic energy of emitted particles in the range from about 50 to 150 MeV. This suggests that some important non-equilibrium mechanism is lacking in the present day microscopic models of proton-nucleus collisions in the studied beam energy range.

Measurements of the ${}^{169}\mathrm{Tm}(n,2n){}^{168}\mathrm{Tm}$ cross section have been performed via the activation technique at 13 energies between 8.5 and 15.0 MeV. The purpose of this comprehensive data set is to provide an alternative diagnostic tool for obtaining subtle information on the neutron energy distribution produced in inertial confinement deuterium-tritium fusion experiments at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. The ${}^{169}\mathrm{Tm}(n,2n){}^{168}\mathrm{Tm}$ reaction not only provides the primary 14-MeV neutron fluence, but also the important down-scattered neutron fluence, the latter providing information on the density achieved in the deuterium-tritium plasma during a laser shot.