The $\alpha$-decay half-lives of recently synthesized superheavy nuclei (SHN) are investigated by employing a unified fission model (UFM) where a new method to calculate the assault frequency of $\alpha$ emission is used. The excellent agreement with the experimental data indicates the UFM is a useful tool to investigate these $\alpha$ decays. It is found that the $\alpha$-decay half-lives become more and more insensitive to the $Q_{\alpha }$ values as the atomic number increases on the whole, which is favorable for us to predict the half-lives of SHN. In addition, a formula is proposed to compute the $Q_{\alpha }$ values for the nuclei with $Z⩾92$ and $N⩾140$ with a good accuracy, according to which the long-lived SHN should be neutron rich. Several weeks ago, two isotopes of a new element with atomic number $Z=117$ were synthesized and their $\alpha$-decay chains have been observed. The $Q_{\alpha }$ formula is found to work well for these nuclei, confirming its predictive power. The experimental half-lives are well reproduced by employing the UFM with the experimental $Q_{\alpha }$ values. This fact that the experimental half-lives are compatible with experimental $Q_{\alpha }$ values supports the synthesis of a new element $117$ and the experimental measurements to a certain extent.

We report a measurement of high-$p_T$ inclusive ${\pi }^0$, $\eta$, and direct photon production in $p+p$ and $d+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\hspace{0.5em}\mathrm{GeV}$ at midrapidity ($0<\eta <1$). Photons from the decay ${\pi }^0\to \gamma \gamma$ were detected in the barrel electromagnetic calorimeter of the STAR experiment at the Relativistic Heavy Ion Collider. The $\eta \to \gamma \gamma$ decay was also observed and constituted the first $\eta$ measurement by STAR. The first direct photon cross-section measurement by STAR is also presented; the signal was extracted statistically by subtracting the ${\pi }^0$, $\eta$, and $\omega$$(782)$ decay background from the inclusive photon distribution observed in the calorimeter. The analysis is described in detail, and the results are found to be in good agreement with earlier measurements and with next-to-leading-order perturbative QCD calculations.

The $\gamma$-ray spectroscopy of ${}^{25}\mathrm{Si}$ and ${}^{29}\mathrm{S}$ has been performed using single neutron knockout reactions with intermediate energy beams of the exotic isotopes ${}^{26}\mathrm{Si}$ and ${}^{30}\mathrm{S}$. Two $\gamma$ rays have been observed in ${}^{25}\mathrm{Si}$ and three in ${}^{29}\mathrm{S}$. These are the first $\gamma$ rays observed in these two isotopes. These two nuclei appear to be well deformed, and possible future intermediate-energy Coulomb excitation measurements would confirm their rotational nature.

Anomalous soft photons in excess of what is expected from electromagnetic bremsstrahlung have been observed in association with the production of hadrons, mostly mesons, in high-energy $K^{+}p$, ${\pi }^{+}p$, ${\pi }^{-}p$, $\mathit{pp}$, and $e^{+}{e}^{-}$ collisions. We propose a model for the simultaneous production of anomalous soft photons and mesons in quantum field theory, in which the meson production arises from the oscillation of color charge densities of the quarks of the underlying vacuum in the flux tube. Because a quark carries both a color charge and an electric charge, the oscillation of the color charge densities will be accompanied by the oscillation of electric charge densities, which will in turn lead to the simultaneous production of soft photons during the meson production process. How the production of these soft photons may explain the anomalous soft photon data is discussed. Further experimental measurements to test the model are proposed.

Measurements of spin observables in $\mathit{pp}\to \mathrm{p⃗}\mathrm{p⃗}{\pi }^0$ are suggested to remove the phase ambiguity of the threshold amplitude. The suggested measurements complement the Indiana University Cyclotron Facility data on $\mathrm{p⃗}\mathrm{p⃗}\to \mathit{pp}{\pi }^0$ to completely determine all the 12 partial wave amplitudes taken into consideration by Meyer et al. [Phys. Rev. C 63, 064002 (2001)] and Deepak et al. [Phys. Rev. C 72, 024004 (2005)].

The optimized perturbation theory (OPT) method is applied to the SU(2) version of the Nambu–Jona-Lasinio (NJL) model both at zero and at finite temperature and/or density. At the first nontrivial order, the OPT exhibits a class of $1/N_c$ corrections which produce nonperturbative results that go beyond the standard large-$N_c$ or mean-field approximation. The consistency of the OPT method with the Goldstone theorem at this order is established, and appropriate OPT values of the basic NJL (vacuum) parameters are obtained by matching the pion mass and decay constant consistently. Deviations from standard large-$N_c$ relations induced by OPT at this order are derived, for example, for the Gell-Mann–Oakes–Renner relation. Next, the results for the critical quantities and the phase diagram of the model, as well as a number of other thermodynamical quantities of interest, are obtained with OPT and then contrasted with the corresponding results at large $N_c$.

We present a detailed study of partial-wave contributions of nuclear forces to pairing in nuclei. For $T=1,J=0$ pairing, partial waves beyond the standard ${}^1{\mathcal{S}}_0$ channel play an interesting role for the pair formation in nuclei. The additional contributions are dominated by the repulsive ${}^3{\mathcal{P}}_1$ partial wave. Their effects, and generally spin-triplet nuclear forces between paired nucleons, are influenced by the interplay of spin-orbit partners. We explore the impact of including partial waves beyond the ${}^1{\mathcal{S}}_0$ channel on neutron-neutron pairing gaps in semimagic isotopic chains. In addition, we show that nuclear forces favor $T=1,J=0$ over $T=0,J=1$ pairing, except in low-$j$ orbitals. This is in contrast to the free-space motivation that suggests the formation of deuteron-like $T=0$ pairs in $N=Z$ nuclei. The suppression of $T=0$ pairing is because the ${}^3{\mathcal{S}}_1$ strength is distributed on spin-orbit partners and because of the effects of the repulsive ${}^1{\mathcal{P}}_1$ channel and of $D$ waves.

A quantitative comparison is made between the absolute cross sections associated with statistical and dynamical emission of heavy fragments in the ${}^{124}\mathrm{Sn}+{}^{64}\mathrm{Ni}$ and ${}^{112}\mathrm{Sn}+{}^{58}\mathrm{Ni}$ collisions experimentally investigated at 35$A$ MeV beam energy using the multidetector CHIMERA. The result shows that the dynamical process is about twice as probable in the neutron-rich ${}^{124}\mathrm{Sn}+{}^{64}\mathrm{Ni}$ system as in the ${}^{112}\mathrm{Sn}+{}^{58}\mathrm{Ni}$ neutron-poor one. This unexpected and significant difference indicates that the reaction mechanism is strongly dependent on the entrance-channel isospin ($N/Z$) content.

We present a calculation of the properties of vibrational states in deformed, axially-symmetric even-even nuclei, within the framework of a fully self-consistent quasiparticle random phase approximation (QRPA). The same Skyrme energy density and density-dependent pairing functionals are used to calculate the mean field and the residual interaction in the particle-hole and particle-particle channels. We have tested our software in the case of spherical nuclei against fully self-consistent calculations published in the literature, finding excellent agreement. We investigate the consequences of neglecting the spin-orbit and Coulomb residual interactions in QRPA. Furthermore we discuss the improvement obtained in the QRPA result associated with the removal of spurious modes. Isoscalar and isovector responses in the deformed ${}^{24–26}\mathrm{Mg}$, ${}^{34}\mathrm{Mg}$ isotopes are presented and compared to experimental findings.

We investigate the in-medium masses of $D$ and $\mathrm{D̄}$ mesons in the isospin-asymmetric nuclear matter at finite temperatures arising due to the interactions with the nucleons, the scalar-isoscalar meson $\sigma$, and the scalar-isovector meson $\delta$ within a SU(4) model. However, since the chiral symmetry is explicitly broken for the SU(4) case due to the large charm quark mass, we use the SU(4) symmetry here only to obtain the interactions of the $D$ and $\mathrm{D̄}$ mesons with the light hadron sector but use the observed values of the heavy hadron masses and empirical values of the decay constants. The in-medium masses of $J/\psi$ and the excited charmonium states [$\psi (3686)$ and $\psi (3770)$] are also calculated in the hot isospin-asymmetric nuclear matter in the present investigation. These mass modifications arise due to the interaction of the charmonium states with the gluon condensates of QCD, simulated by a scalar dilaton field introduced to incorporate the broken scale invariance of QCD within the effective chiral model. The change in the mass of $J/\psi$ in the nuclear matter with the density is seen to be rather small, as has been shown in the literature by using various approaches, whereas the masses of the excited states of charmonium [$\psi (3686)$ and $\psi (3770)$] are seen to have considerable drop at high densities. The present study of the in-medium masses of $D$ ($\mathrm{D̄}$) mesons as well as of the charmonium states will be of relevance for the observables from the compressed baryonic matter, like the production and collective flow of the $D$ ($\mathrm{D̄}$) mesons, resulting from the asymmetric heavy-ion collision experiments planned at the future facility of the GSI Facility for Antiproton and Ion Research. The mass modifications of $D$ and $\mathrm{D̄}$ mesons as well as of the charmonium states in hot nuclear medium can modify the decay of the charmonium states (${\Psi }^{\prime },{\chi }_c,J/\Psi$) to $D\mathrm{D̄}$ pairs in the hot dense hadronic matter. The small attractive potentials observed for the $\mathrm{D̄}$ mesons may lead to formation of the $\mathrm{D̄}$ mesic nuclei.

We investigate effects of cluster particle correlations on two- and three-particle azimuth correlator observables sensitive to local strong parity violation. We use two-particle angular correlation measurements as inputs and estimate the magnitudes of the effects with straightforward assumptions. We found that the measurements of the azimuth correlator observables in the STAR experiment can be entirely accounted for by cluster particle correlations together with a reasonable range of cluster anisotropy in nonperipheral collisions. Our result suggests that new physics, such as local strong parity violation, may not be required to explain the correlator data.

In a Poincaré-covariant vector-boson-exchange theory, the pion possesses components of pseudovector origin, which materially influence its observable properties. For a range of such quantities, we explore the consequences of a momentum-independent interaction, regularized in a symmetry-preserving manner. The contact interaction, while capable of describing pion static properties, produces a form factor whose evolution for $Q^2>0.17\hspace{0.5em}$GeV${}^2$ disagrees markedly with experiment and whose asymptotic power-law behavior conflicts strongly with perturbative QCD.

Finite energy sum rules for vector and axial-vector currents are derived in a thermal medium to provide constraints for the spectral behavior of $\rho$ and $a_1$ mesons at nonvanishing temperature and hence to study the tendency toward chiral symmetry restoration. The parity-mixing ansatz for the $\rho$ and $a_1$ spectra, including finite widths, is investigated as a function of temperature. Characteristic differences between vector and axial-vector channels are discussed with regard to the implementation of the chiral-symmetry-breaking scale, $4\pi$ times the pion decay constant, in the sum-rule approach.

The mass and isospin dependence of symmetry energy coefficients $a_{\mathrm{sym}}$ of finite nuclei are investigated with the measured nuclear masses incorporating the liquid drop mass formula. The enhanced $a_{\mathrm{sym}}$ for nearly symmetric nuclei are observed. To describe the mass and isospin dependence of $a_{\mathrm{sym}}$, a modified formula based on the conventional surface-symmetry term is proposed and the corresponding rms deviation of nuclear masses is checked.

Monte Carlo simulations are used to compute the centrality dependence of the collision zone eccentricities (${\varepsilon }_{2,4}$), for both spherical and deformed ground state nuclei, for different model scenarios. Sizable model dependent differences are observed. They indicate that measurements of the second and fourth order Fourier flow coefficients $v_{2,4}$, expressed as the ratio $\frac{v_4}{(v_2){}^2}$, can provide robust constraints for distinguishing between different theoretical models for the initial-state eccentricity. Such constraints could remove one of the largest impediments to a more precise determination of the specific viscosity from precision $v_{2,4}$ measurements at the Relativistic Heavy Ion Collider (RHIC).

An evaluation of data obtained in ($n,n^{\prime }\gamma$) experiments reveals strong $M1$ $3_i^{-}\to 3_1^{-}$ transitions in nuclei near the $N=50$ (${}^{92}\mathrm{Zr}$, ${}^{94}\mathrm{Mo}$, and ${}^{96}\mathrm{Mo}$), $Z=50$ (${}^{112}\mathrm{Cd}$ and ${}^{114}\mathrm{Cd}$), and $N=82$ (${}^{144}\mathrm{Nd}$) shell closures. The observed $\langle 3_1^{-}\left|\right|M1\left|\right|3_i^{-}\rangle$ matrix elements scale with the $\langle 2_1^{+}\left|\right|M1\left|\right|2_{\mathrm{ms}}^{+}\rangle$ matrix elements connecting the mixed-symmetric and symmetric quadrupole excitations. In accordance with a picture of a mixed two-component quantum system, the energy difference between the initial $3_i^{-}$ state and the $3_1^{-}$ octupole phonon is proportional to the $|\langle 3_1^{-}|\left|E3\right||0_{\mathrm{gs}}^{+}\rangle |$ matrix element. The possibility of assigning the $3^{-}$ states of interest as octupole isovector states is discussed.

Overlap functions for one-nucleon removal are calculated as solutions of the inhomogeneous equation. The source term for this equation is generated by the $0\hslash \omega$ no-core shell-model wave functions and the effective nucleon-nucleon ($\mathit{NN}$) interactions that fit oscillator matrix elements derived from the $\mathit{NN}$ scattering data. For the lightest $A⩽4$ nuclei this method gives reasonable agreement with exact ab initio calculations. For $4<A⩽16$, this method gives a fair agreement between the calculated and measured asymptotic normalization coefficients. The spectroscopic factors obtained show systematic deviation from the corresponding shell-model values. This deviation correlates with nucleon separation energies and follows a similar trend seen in the reduction factor of the nucleon knockout cross sections. Comparison with the overlap functions and spectroscopic factors obtained in the variational Monte Carlo method is presented and discussed.

Measurements of the ${}^{241}\mathrm{Am}$($n,2n$) reaction cross section have been performed at the Joint Research Centre (JRC) Geel in the frame of a collaboration between the European Commission (EC) JRC and French laboratories from CNRS and the Commissariat à L’Energie Atomique (CEA) Cadarache. Raw material coming from the Atalante facility of CEA Marcoule has been transformed by JRC Karlsruhe into suitable ${}^{241}\mathrm{Am}$O${}_2$ samples embedded in Al${}_2$O${}_3$ matrices specifically designed for these measurements. The irradiations were carried out at the $7$-MV Van de Graaff accelerator. The ${}^{241}\mathrm{Am}$($n,2n$) reaction cross section was determined relative to the ${}^{27}\mathrm{Al}$($n,\alpha$)${}^{24}\mathrm{Na}$ standard cross section. The measurements were performed in four sessions, using quasi-mono-energetic neutrons with energies ranging from $8$ to $21$ MeV produced via the ${}^2\mathrm{H}$($d,n$)${}^3\mathrm{He}$ and the ${}^3\mathrm{H}$($d,n$)${}^4\mathrm{He}$ reactions. The induced activity was measured by standard $\gamma$-ray spectrometry using a high-purity germanium detector. Below $15$ MeV, the present results are in agreement with data obtained earlier. Above 15 MeV, these measurements allowed the experimental investigation of the ${}^{241}\mathrm{Am}$($n,2n$) reaction cross section for the first time. The present data are in good agreement with predictions obtained with the talys code that uses an optical and fission model developed at CEA.

A simple approach is proposed allowing actual calculations of the preequilibrium dynamics in ultrarelativistic heavy-ion collisions to be performed for a far-from-equilibrium initial state. The method is based on the phenomenological macroscopic equations that describe the relaxation dynamics of the energy-momentum tensor and are motivated by Boltzmann kinetics in the relaxation-time approximation. It gives the possibility to match smoothly a nonthermal initial state to the hydrodynamics of the quark gluon plasma. The model contains two parameters, the duration of the prehydrodynamic stage and the initial value of the relaxation-time parameter, and allows one to assess the energy-momentum tensor at a supposed time of initialization of the hydrodynamics.

The deformed doubly magic nucleus ${}^{270}\mathrm{Hs}$ has so far only been observed as the four-neutron ($4n$) evaporation residue of the reaction ${}^{26}\mathrm{Mg}+{}^{248}\mathrm{Cm}$, where a maximum cross section of $3$ pb was measured. Theoretical studies on the formation of ${}^{270}\mathrm{Hs}$ in the $4n$ evaporation channel of fusion reactions with different entrance channel asymmetry in the framework of a two-parameter Smoluchowski equation predict that the reactions ${}^{48}\mathrm{Ca}+{}^{226}\mathrm{Ra}$ and ${}^{36}\mathrm{S}+{}^{238}\mathrm{U}$ result in higher cross sections due to lower reaction $Q$ values, in contrast to simple arguments based on the reaction asymmetry, which predict opposite trends. Calculations using hivap predict cross sections for the reaction ${}^{36}\mathrm{S}+{}^{238}\mathrm{U}$ that are similar to those of the ${}^{26}\mathrm{Mg}+{}^{248}\mathrm{Cm}$ reaction. Here, we report on the first measurement of evaporation residues formed in the complete nuclear fusion reaction ${}^{36}\mathrm{S}+{}^{238}\mathrm{U}$ and the observation of ${}^{270}\mathrm{Hs}$, which is produced in the $4n$ evaporation channel, with a measured cross section of $0.8_{-0.7}^{+2.6}$ pb at $51$-MeV excitation energy. The one-event cross-section limits ($68\%$ confidence level) for the $3n$, $4n$, and $5n$ evaporation channels at $39$-MeV excitation energy are $2.9$ pb, while the cross-section limits of the $3n$ and $5n$ channel at $51$ MeV are $1.5$ pb. This is significantly lower than the $5n$ cross section of the ${}^{26}\mathrm{Mg}+{}^{248}\mathrm{Cm}$ reaction at similar excitation energy.