We implemented a variation after projection (VAP) algorithm based on a triaxially deformed Hartree-Fock-Bogoliubov vacuum state. This is the first projected mean field study that includes all the quantum numbers (except parity), i.e., spin ($J$), isospin ($T$), and mass number ($A$). Systematic VAP calculations with $\mathrm{JTA}$ projection have been performed for the even-even $sd$-shell nuclei with the USDB Hamiltonian. All the VAP ground state energies are within 500 keV above the exact shell model values. Our VAP calculations show that the spin projection has two important effects: (1) the spin projection is crucial in achieving good approximation of the full shell model calculation; (2) the intrinsic shapes of the VAP wave functions with spin projection are always triaxial, while the Hartree-Fock-Bogoliubov methods likely provide axial intrinsic shapes. Finally, our analysis suggests that one may not be possible to associate an intrinsic shape to an exact shell model wave function.

The effective-surface approximation is extended taking into account derivatives of the symmetry-energy density per particle with respect to the mean particle density. The isoscalar and isovector particle densities in this extended effective-surface approximation are derived. The improved expressions of the surface symmetry energy, in particular, its surface tension coefficients in the sharp-edged proton-neutron asymmetric nuclei take into account important gradient terms of the energy density functional. For most Skyrme forces the surface symmetry-energy constants and the corresponding neutron skins and isovector stiffnesses are calculated as functions of the Swiatecki derivative of the nongradient term of the symmetry-energy density per particle with respect to the isoscalar density. Using the analytical isovector surface-energy constants in the framework of the Fermi-liquid droplet model we find energies and sum rules of the isovector giant dipole-resonance structure in a reasonable agreement with the experimental data, and they are compared with other theoretical approaches.

Several new subnanosecond lifetimes were measured in ${}^{109}\mathrm{Pd}$ using the fast-timing $\beta \gamma \gamma \left(t\right)$ method. Fission fragments of the $A=109$ mass chain were produced by bombarding natural uranium with 30 MeV protons at the Jyväskylä Ion Guide Isotope Separator On-Line (IGISOL) facility. Lifetimes were obtained for excited states in ${}^{109}\mathrm{Pd}$ populated following $\beta$ decay of ${}^{109}\mathrm{Rh}$. The new lifetimes provide some insight into the evolution of nuclear structure in this mass region. In particular, the distinct structure of the two low-lying $7/2^{+}$ states occurring systematically across the Pd isotopic chain is supported by the new lifetime measurements. The available nuclear data indicate a sudden increase in deformation at $N=60$ which is related to the strong $p-n$ interaction between $\pi g_{9/2}$ and $\nu g_{7/2}$ valence nucleons expected in this region.

In ${}^{129}\text{Xe}+{}^{\text{nat}}\text{Sn}$ central collisions from 8 to 25 MeV/nucleon, the three-fragment exit channel occurs with a significant cross section. We show that these fragments arise from two successive binary splittings of a heavy composite system. The sequence of fragment production is determined. Strong Coulomb proximity effects are observed in the three-fragment final state. A comparison with Coulomb trajectory calculations shows that the time scale between the consecutive breakups decreases with increasing bombarding energy, becoming quasisimultaneous above excitation energy $E^{*}=4.0\pm 0.5\mathrm{MeV}/\mathrm{nucleon}$. This transition from sequential to simultaneous breakup was interpreted as the signature of the onset of multifragmentation for the three-fragment exit channel in this system.

Background: No data on the fusion excitation function of ${}^{48}\mathrm{Ti}+{}^{58}\mathrm{Fe}$ in the energy region near the Coulomb barrier existed prior to the present work, while fusion of ${}^{58}\mathrm{Ni}+{}^{54}\mathrm{Fe}$ was investigated in detail some years ago, down to very low energies, and clear evidence of fusion hindrance was noticed at relatively high cross sections. ${}^{48}\mathrm{Ti}$ and ${}^{58}\mathrm{Fe}$ are soft and have a low-lying quadrupole excitation lying at $\approx 800–900$ keV only. Instead, ${}^{58}\mathrm{Ni}$ and ${}^{54}\mathrm{Fe}$ have a closed shell (protons and neutrons, respectively) and are rather rigid.

Purpose: We aim to investigate (1) the possible influence of the different structures of the involved nuclei on the fusion excitation functions far below the barrier and, in particular, (2) whether hindrance is observed in ${}^{48}\mathrm{Ti}+{}^{58}\mathrm{Fe}$, and to compare the results with current coupled-channels models.

Methods: ${}^{48}\mathrm{Ti}$ beams from the XTU Tandem accelerator of INFN-Laboratori Nazionali di Legnaro were used. The experimental setup was based on an electrostatic beam separator, and fusion-evaporation residues (ERs) were detected at very forward angles. Angular distributions of ERs were measured.

Results: Fusion cross sections of ${}^{48}\mathrm{Ti}+{}^{58}\mathrm{Fe}$ have been obtained in a range of nearly six orders of magnitude around the Coulomb barrier, down to $\sigma \simeq 2 \mu \mathrm{b}$. The sub-barrier cross sections of ${}^{48}\mathrm{Ti}+{}^{58}\mathrm{Fe}$ are much larger than those of ${}^{58}\mathrm{Ni}+{}^{54}\mathrm{Fe}$. Significant differences are also observed in the logarithmic derivatives and astrophysical $S$ factors. No evidence of hindrance is observed, because coupled-channels calculations using a standard Woods-Saxon potential are able to reproduce the data in the whole measured energy range. Analogous calculations for ${}^{58}\mathrm{Ni}+{}^{54}\mathrm{Fe}$ predict clearly too large cross sections at low energies. The two fusion barrier distributions are wide and display a complex structure that is only qualitatively fit by calculations.

Conclusions: It is pointed out that all these different trends originate from the dissimilar low-energy nuclear structures of the involved nuclei. In particular, the strong quadrupole excitations in ${}^{48}\mathrm{Ti}$ and ${}^{58}\mathrm{Fe}$ produce the relative cross section enhancement and make the barrier distribution $\approx 2$ MeV wider, thus probably pushing the threshold for hindrance below the measured limit.

We explore the influence of deuteron formation in the late stage of nucleus-nucleus reactions on the fluctuations observed in the final net-proton yields around midrapidity. At each investigated energy, the produced (anti)proton yield at chemical freeze-out is assumed to fluctuate according to a Poisson distribution and in each event the probability for deuteron formation by coalescence is proportional to ${(d{N}_{\mathrm{proton}}/dy)}^2$. The protons that are then clustered in deuterons are usually not included in the experimental measurement of the net-proton fluctuations, therefore, we subtract these clustered protons from the final state proton number for the calculation of the net-proton fluctuations (the same is done in the antiproton sector). Due to the nonlinear deuteron formation probability the resulting distribution is not a Skellam distribution, but shows the interesting feature of a decrease in the kurtosis $\kappa {\sigma }^2$ and a local maximum in the skewness $S\sigma$ observables as the collision energy decreases.

We derive the second-order hydrodynamic equation for reactive multicomponent systems from the relativistic Boltzmann equation. In the reactive system, particles can change their species under the restriction of the imposed conservation laws during the collision process. Our derivation is based on the renormalization-group method, in which the Boltzmann equation is solved in an organized perturbation method as faithfully as possible and possible secular terms are resummed away by a suitable setting of the initial value of the distribution function. The microscopic formulas of the relaxation times and the lengths are explicitly given as well as those of the transport coefficients for the reactive multicomponent system. The resultant hydrodynamic equation with these formulas has nice properties that it satisfies the positivity of the entropy-production rate and the Onsager's reciprocal theorem, which ensure the validity of our derivation.

We present measurements of the upscattering cross sections of ultracold neutrons (UCNs) from room-temperature hydrogen, deuterium, neon, argon, xenon, ${\mathrm{C}}_4{\mathrm{H}}_{10}, \mathrm{C}{\mathrm{F}}_4$, and air. The values of these cross sections are important for estimating the loss rate of trapped neutrons due to residual gas and are therefore of importance for neutron lifetime measurements using UCNs. Cross sections were obtained from a combined analysis of the UCN attenuation in a gas cell and direct measurement of the neutrons upscattered in the cell. The effects of the UCN velocity and path-length distributions were accounted for using a Monte Carlo transport code. Results are compared with measurements at higher neutron energy as well as with calculations.

Baryon number density perturbations offer a possible route to experimentally measure baryon number susceptibilities and heat conductivity of the quark gluon plasma. We study the fluid dynamical evolution of local and event-by-event fluctuations of baryon number density, flow velocity, and energy density on top of a (generalized) Bjorken expansion. To that end we use a background-fluctuation splitting and a Bessel-Fourier decomposition for the fluctuating part of the fluid dynamical fields with respect to the azimuthal angle, the radius in the transverse plane, and rapidity. We examine how the time evolution of linear perturbations depends on the equation of state as well as on shear viscosity, bulk viscosity, and heat conductivity for modes with different azimuthal, radial, and rapidity wave numbers. Finally we discuss how this information is accessible to experiments in terms of the transverse and rapidity dependence of correlation functions for baryonic particles in high energy nuclear collisions.

We present an attempt to closely mimic the initial stage of heavy ion collisions within holography, assuming a decoupling of longitudinal and transverse dynamics in the very early stage. We subsequently evolve the obtained initial state using state-of-the-art hydrodynamic simulations and compare results with experimental data. We present results for charged hadron pseudorapidity spectra and directed and elliptic flow as functions of pseudorapidity for $\sqrt{s_{NN}}=200\mathrm{GeV}$ Au-Au and $2.76\mathrm{TeV}$ Pb-Pb collisions. The directed flow interestingly turns out to be quite sensitive to the viscosity. The results can explain qualitative features of the collisions, but the rapidity spectra in our current model is narrower than the experimental data.

The production of the $f_1\left(1285\right)$ resonance in the reaction of $K^{-}p\to f_1\left(1285\right)\mathrm{\Lambda }$ is studied within an effective Lagrangian approach. The production process is described by the $t$ channel $K^{*+}$ meson exchange. My theoretical approach is based on the results of chiral unitary theory where the $f_1\left(1285\right)$ resonance is dynamically generated from the single channel $\overline{K}{K}^{*}-c.c.$ interaction. The total and differential cross sections of the $K^{-}p\to f_1\left(1285\right)\mathrm{\Lambda }$ reaction are evaluated. Within the coupling constant of the $f_1\left(1285\right)$ to $\overline{K}{K}^{*}$ channel obtained from the chiral unitary theory and a cut off parameter ${\mathrm{\Lambda }}_c\sim 1.5$ GeV in the form factors, the experimental measurement can be reproduced. This production process would provide further evidence for the $\overline{K}{K}^{*}-c.c.$ nature of the $f_1\left(1285\right)$ state.

We comment on the statement by Kuznetsov et al. that the structure around $W=1.72$ GeV seen in the beam asymmetry in Compton scattering off the proton is not observed in the total cross section of $\eta$ photoproduction on the neutron.

A new integral formula, which has not been compiled in any integral tables or mathematical softwares, is proposed to obtain the analytical energy-angular spectra of the particles that are sequentially emitted from the discrete energy levels of the residual nuclei in the statistical theory of light nucleus reaction (STLN). In the cases of the neutron induced light nucleus reactions, the demonstration of the kinetic energy conservation in the sequential emission processes becomes straightforward thanks to this new integral formula and it is also helpful to largely reduce the volume of file-6 in nuclear reaction databases. Furthermore, taking $p + {}^9\mathrm{Be}$ reaction at 18 MeV as an example, this integral formula is extended to calculate the energy-angular spectra of the sequentially emitted neutrons for proton induced light nucleus reactions in the frame of STLN.

The weak interaction rates for the $Z=N+2$ isotopes ${}^{70}\mathrm{Kr}$ and ${}^{74}\mathrm{Sr}$ dominated by shape coexistence are self-consistently investigated within the beyond-mean-field complex excited Vampir variational model using an effective interaction obtained from a $G$ matrix based on the charge-dependent Bonn CD potential. Results are presented on $\beta$-decay properties under terrestrial conditions as well as the contribution of the thermally populated low-lying excited states of ${}^{70}\mathrm{Kr}$ and ${}^{74}\mathrm{Sr}$ in the x-ray burst astrophysical environment on the effective half-lives.

The quasiparticle-random-phase approximation is used to study the properties of the wobbling bands in ${}^{163}\mathrm{Lu}$. Assuming that the wobbling mode represents pure isoscalar orientation oscillations results in too low wobbling frequencies and transition probabilities between the one- and zero-phonon wobbling bands that are strongly collective but yet too weak for $B{\left(E2\right)}_{\mathrm{out}}$ and too strong for $B{\left(M1\right)}_{\mathrm{out}}$. The inclusion of an LL interaction, which couples the wobbling mode to the scissors mode, generates the right upshift of the wobbling frequencies and the right suppression of the $B{\left(M1\right)}_{\mathrm{out}}$ values toward the experimental values, but does not change the $B{\left(E2\right)}_{\mathrm{out}}$ values. In analogy to the quenching of low-energy $E1$ transition by coupling to the isovector giant dipole resonance, a general reduction of the $M1$ transitions between quasiparticle configurations caused by coupling to the scissors mode is suggested. The small $\mathrm{B}{\left(E2\right)}_{\mathrm{out}}$ values are related to small triaxiality of the density distribution, which is found by all mean field calculations for the triaxial strongly deformed nuclei in the mass 160 region.

Lifetime measurements have been carried out using the Doppler shift attenuation method (DSAM) for the negative- and positive-parity bands built on $\pi h_{11/2}\otimes \nu \left(d_{5/2}{g}_{7/2}\right)$ and $\pi h_{11/2}\otimes \nu h_{11/2}$ configurations, respectively, in ${}^{124}\text{Cs}$. The reduced transition probabilities have been obtained for both the bands and are compared with the available theoretical calculations. The enhanced $B\left(E1\right)$ rates for the linking transitions between the bands with the above configurations suggest the existence of octupole correlations in ${}^{124}\text{Cs}$. The observed electromagnetic properties for the positive-parity bands in ${}^{124}\text{Cs}$ agree well with the characteristics pattern required for chiral symmetry breaking.

Mass measurements have been performed of the neutron-rich Al isotopes near $N\approx 20$, along the island of inversion. In general, the precision of the mass values was improved by an order of magnitude. Based on these new and more accurate data, we find the two-neutron separation energy of ${}_{13}{}^{34}\mathrm{Al}$ to be 24.8(10.8) keV less than that of ${}_{12}{}^{33}\mathrm{Mg}$. This represents the first known crossover on the $S_{2n}$ surface of the chart of nuclides. Large-scale shell-model calculations show that the crossover can be attributed to exceptionally large energy gains of the Mg isotopes in the island of inversion.

We present the dominant two- and three-pion-exchange contributions to the nucleon-nucleon interaction at sixth order (next-to-next-to-next-to-next-to-next-to-leading order, ${\mathrm{N}}^5\mathrm{LO}$) of chiral perturbation theory. Phase shifts with orbital angular momentum $L\ge 4$ are given parameter free at this order and allow for a systematic investigation of the convergence of the chiral expansion. The ${\mathrm{N}}^5\mathrm{LO}$ contribution is prevailingly repulsive and considerably smaller than the ${\mathrm{N}}^4\mathrm{LO}$ one, thus, showing the desired trend towards convergence. Using low-energy constants that were extracted from an analysis of $\pi N$ scattering at fourth order, the predictions at ${\mathrm{N}}^5\mathrm{LO}$ are in excellent agreement with the empirical phase shifts of peripheral partial waves.

The decay of the $Z=118$, ${}^{297}118^{*}$ compound system, formed in the ${}^{249}\mathrm{Cf}+{}^{48}\mathrm{Ca}$ reaction, is studied for $2n$, $3n$, and $4n$ emissions, by using the dynamical cluster-decay model (DCM) at compound-nucleus (CN) excitation energies $E_{\mathrm{CN}}^{*}=29.2$ and 34.4 MeV. A parallel attempt is made to analyze the ${}^{294}118$ residue nucleus synthesized in the ${}^{250}\mathrm{Cf}+{}^{48}\mathrm{Ca}$ reaction, subsequent to the $4n$ emission from the ${}^{298}118^{*}$ nucleus, to check the possibility of isotopic mixing in the ${}^{249}\mathrm{Cf}$ target used in the ${}^{249}\mathrm{Cf}+{}^{48}\mathrm{Ca}$ reaction. The possible role of deformations and orientations, together with different nuclear proximity potentials, is also investigated. In addition, an exclusive analysis of the mass distributions of $Z=113$ to 118 superheavy nuclei, formed in ${}^{48}\mathrm{Ca}$-induced reactions, is explored within the DCM. A comparative importance of Prox-1977 and Prox-2000 potentials on the $\alpha$-decay chains is also investigated, first by using the preformed cluster model (PCM) for spontaneous decays $\left(T=0\right)$, the $\mathrm{PCM}\left(T=0\right)$, and then analyzing the possible role of excitation energy in PCM, i.e., $\mathrm{PCM}(T\ne 0)$, via the measured recoil energy of the residual ${}^{294}118$ nucleus left after $3n$ emission from ${}^{297}118^{*}$ CN. The branching of $\alpha$ decay to the most-probable clusters is also examined for ${}^{294}118^{*}$ and its subsequent ${}^{290}116^{*}$ and ${}^{286}114^{*}$ parents occurring in the $\alpha$-decay chain. Interestingly, the calculated decay half-lives for some clusters such as ${}^{86}\mathrm{Kr}$, ${}^{84}\mathrm{Se}$, and ${}^{80}\mathrm{Ge}$, referring to doubly magic ${}^{208}\mathrm{Pb}$ or its neighboring daughter nucleus, present themselves as exciting new possibilities, though to date difficult to observe, of heavy cluster emissions in superheavy mass region.