Fully self-consistent band calculation has been performed for slab phase in neutron-star inner crust using the Barcelona-Catania-Paris-Madrid energy density functional. Optimized slab structure is calculated at given baryon density either with fixed proton ratio or with the beta-equilibrium condition. Numerical results indicate neutron band gaps in order of keV to tens of keV, and the mobility of dripped neutrons are enhanced by the Bragg scattering, which leads to the macroscopic effective mass, ${\overline{m}}_z^{*}/m_n=0.65-0.75$ near the bottom of the inner crust in neutron stars. However, there is an ambiguity for definition of free neutrons, especially very near the critical density between the slab and the uniform phases, which may effectively lead to somewhat larger values of effective mass. We also compare the results of the band calculation with those of the Thomas-Fermi (TF) approximation. The TF approximation becomes invalid at low density and at high proton ratio.

An analysis of the astrophysical ${\displaystyle S}$ factor of the proton-proton weak capture (${\displaystyle p+p\to {}^2\mathrm{H}+e^{+}+{\nu }_e}$) is performed on a large energy range covering solar-core and early Universe temperatures. The measurement of ${\displaystyle S}$ being physically unachievable, its value relies on the theoretical calculation of the matrix element ${\displaystyle \mathrm{\Lambda }}$. Surprisingly, ${\displaystyle \mathrm{\Lambda }}$ reaches a maximum near ${\displaystyle 0.13\mathrm{MeV}}$ that has been unexplained until now. A model-independent parametrization of ${\displaystyle \mathrm{\Lambda }}$ valid up to about ${\displaystyle 5\mathrm{MeV}}$ is established on the basis of recent effective-range functions. It provides an insight into the relationship between the maximum of ${\displaystyle \mathrm{\Lambda }}$ and the proton-proton resonance pole at ${\displaystyle (-140-467i)\mathrm{keV}}$ from analytic continuation. In addition, this parametrization leads to an accurate evaluation of the derivatives of ${\displaystyle \mathrm{\Lambda }}$, and hence of ${\displaystyle S}$, in the limit of zero energy.

Good many-body methods for medium and heavy nuclei are important. Here we combine rotational motion with vibrational modes in a novel generator-coordinate method (GCM): starting from a mean-field solution (Hartree-Fock-Bogoliubov), we create nonorthogonal reference states from low-lying quasiparticle Tamm-Dancoff modes, and then project onto states of good angular momentum and particle number. The results we benchmark against full shell model calculations. Even with just a few such modes we find improvement over standard GCM calculations in excitation spectra. We also find significant improvement in $0\nu \beta \beta$ nuclear matrix elements.

Background: Measurements of neutron-unbound states can test nuclear models in very neutron-rich nuclei that, in some cases, cannot be probed with other methods.

Purpose: Search for highly excited neutron-unbound states of ${}^{25}\mathrm{O}$ above the three-neutron separation energy.

Method: The decay energy of ${}^{25}\mathrm{O}$ was reconstructed using the invariant mass spectroscopy method. A 101.3-MeV/u ${}^{27}\mathrm{Ne}$ beam collided with a liquid-deuterium target. Two-proton removal reactions populated excited ${}^{25}\mathrm{O}$ that decayed into three neutrons and an ${}^{22}\mathrm{O}$ fragment. The neutrons were detected by arrays of plastic scintillator bars, whereas a 4-Tm dipole magnet placed directly after the target redirected charged fragments to a series of charged-particle detectors. The data were compared with detailed Monte Carlo simulations of the reaction process and subsequent decay.

Results: The data show evidence of neutron-unbound level(s) in ${}^{25}\mathrm{O}$ at an excitation energy of about 9 MeV which decay sequentially by the emission of three neutrons to ${}^{22}\mathrm{O}$.

Conclusion: The observation of resonance strength in ${}^{25}\mathrm{O}$ at about 9 MeV is consistent with shell-model and eikonal calculations for the two-proton removal reaction from ${}^{27}\mathrm{Ne}$.

We present a study of the role played by realistic three-body forces in providing a reliable monopole component of the effective shell-model Hamiltonian. To this end, starting from a nuclear potential built up within the chiral perturbation theory, we derive effective shell-model Hamiltonians with and without the contribution of the three-body potential and compare the results of shell-model calculations with a set of observables that evidence shell-evolution properties. The testing ground of our investigation is nuclei belonging to the $fp$ shell, since the shell-evolution towards shell closures in ${}^{48}\mathrm{Ca}$ and ${}^{56}\mathrm{Ni}$ provides a paradigm for shell-model Hamiltonians. Our analysis shows that only by including contributions of the three-body force is the monopole component of the effective shell-model Hamiltonian then able to reproduce the experimental shell evolution towards and beyond the closure at $N=28$.

Using the high-resolution ${}^{18}\mathrm{O}({}^3\mathrm{He},t){}^{18}\mathrm{F}$ reaction at $0^{\circ }$ and at 140 MeV/nucleon, Gamow-Teller (GT) transitions were studied. A high energy resolution of 31 keV was achieved by applying dispersion matching techniques. The main part of the observed GT transition strength is concentrated in the transition to the ${}^{18}\mathrm{F}$ ground state (g.s.). The absolute values of the reduced GT transition strengths, $B\left(\mathrm{GT}\right)$, were derived up to $E_x=12$ MeV assuming proportionality between the $B\left(\mathrm{GT}\right)$ values and the reaction cross sections at $0^{\circ }$. The $B\left(\mathrm{GT}\right)$ value obtained from the $\beta$ decay of ${}^{18}\mathrm{F}$ (g.s.) $\to {}^{18}\mathrm{O}$ (g.s.) was used to determine the proportionality constant. A total $B\left(\mathrm{GT}\right)$ of 4.06(5) was found and 76(1)% of the strength is concentrated to the ground state of ${}^{18}\mathrm{F}$. The obtained $B\left(\mathrm{GT}\right)$ values were compared with those from the ${}^{18}\mathrm{O}(p,n){}^{18}\mathrm{F}$ reaction and the mirror symmetric ${\beta }^{+}$ decay of ${}^{18}\mathrm{Ne}\to {}^{18}\mathrm{F}$. The candidates for $1^{+}$ states with isospin $T=1$ were identified by comparison with the ${}^{18}\mathrm{O}(p,p^{\prime }$) data. The results of shell-model and quasiparticle-random-phase approximation calculations suggest constructive contributions of various configurations to the ${}^{18}\mathrm{F}$ ground state, suggesting that this state is the low-energy super GT state.

Geometric scaling is well confirmed for transverse-momentum distributions observed in proton-proton collisions at Large Hadron Collider (LHC) energies. We introduced multiplicity dependence on a saturation momentum of the geometrical scaling, assuming the scaling holds for semi-inclusive distributions as well as for inclusive distributions. The saturation momentum is usually given by Bjorken's $x$ variable, but redefinition of the scaling variable can make the saturation momentum a function of collision energy $W$. We treat the energy as a free parameter (denoted $W^{*}$ to distinguish it from $W$) and associate the energy-dependent saturation momentum $Q_{\mathrm{sat}}\left(W^{*}\right)$ with particle number density. By using $Q_{\mathrm{sat}}\left(W^{*}\right)$ for a scaling variable $\tau$, we show semi-inclusive distributions can be geometrically scaled, i.e., all semi-inclusive spectra observed at $W=0.90$, 2.76, and 7.00 TeV overlap one universal function. The particle density dependencies of mean transverse momentum $\langle p_T\rangle$ for LHC energies scales in terms of $Q_{\mathrm{sat}}\left(W^{*}\right)$. Furthermore, our model explains a scaling property of event-by-event $p_T$ fluctuation measure $\sqrt{C_m}/\langle p_T\rangle$ at LHC energies for $pp$ collisions, where $C_m$ is a two-particle transverse-momentum correlator. Our analysis of the $p_T$ fluctuation makes possible to evaluate a nonperturbative coefficient of the gluon correlation function.

Incoherent ${\pi }^0$ photoproduction on a deuteron in the $\mathrm{\Delta }\left(1232\right)$ region is treated in a three-body scattering approach using separable two-body interactions. Results are presented for total and differential cross sections. It turns out that the role of higher order terms beyond the first order in the multiple scattering series is insignificant, and their inclusion cannot explain the existing discrepancy between theory and experiment.

The Gamow-Teller strength distribution from ${}^{88}\mathrm{Sr}$ was extracted from a $(t,{}^3\mathrm{He}+\gamma )$ experiment at $115\mathrm{MeV}/\mathrm{u}$ to constrain estimates for the electron-capture rates on nuclei around $N=50$, between and including ${}^{78}\mathrm{Ni}$ and ${}^{88}\mathrm{Sr}$, which are important for the late evolution of core-collapse supernovae. The observed Gamow-Teller strength below an excitation energy of 8 MeV was consistent with zero and below 10 MeV amounted to $0.1\pm 0.05$. Except for a very-weak transition that could come from the 2.231-MeV $1^{+}$ state, no $\gamma$ lines that could be associated with the decay of known $1^{+}$ states were identified. The derived electron-capture rate from the measured strength distribution is more than an order of magnitude smaller than rates based on the single-state approximation presently used in astrophysical simulations for most nuclei near $N=50$. Rates based on shell-model and quasiparticle random-phase approximation calculations that account for Pauli-blocking and core-polarization effects provide better estimates than the single-state approximation, although a relatively strong transition to the first $1^{+}$ state in ${}^{88}\mathrm{Rb}$ is not observed in the data. Pauli-unblocking effects due to high stellar temperatures could partially counter the low electron-capture rates. The new data serve as a zero-temperature benchmark for constraining models used to estimate such effects.

We calculate the structure of three-body hypernuclei with $S=-1$ using pionless effective field theory at leading order in the isospin $I=0$ and $I=1$ sectors. In both sectors, three-body hypernuclei arise naturally from the Efimov effect and a three-body parameter is required at leading order. We apply our theory to the hypertriton and the hypothetical $\mathrm{\Lambda }nn$ bound state and calculate the corresponding scaling factors. Moreover, we discuss constraints on the existence of the $\mathrm{\Lambda }nn$ bound state. In particular, we elucidate universal correlations between different observables and provide explicit calculations of wave functions and matter radii.

Background: Atomic nuclei are remarkable quantum many-body systems where clustering properties develop naturally from underlying interactions between the constituent nucleons. Clustering degrees of freedom manifest themselves in multiple structure and reaction observables.

Purpose: Our goal is to study nuclear clustering and its emergence in many-nucleon dynamics from nucleon-nucleon interactions. Clustering is a phenomenon that is known to emerge on the boundary between structure and reactions, therefore developing appropriate techniques that bridge the structure-reaction divide and establishing connections to observables is among our principal objectives. Showing consistency and how the new techniques can be reduced to well established other methods is an important part of this work.

Methods: The configuration-interaction technique based on second quantization is used to treat the quantum many-body problem assuring that fermionic antisymmetry is fully satisfied. The use of the harmonic oscillator single-particle basis allows for the center-of-mass coordinate to be separated and prepared in a desired oscillator state for each cluster. The relative motion reaction basis channels are constructed by coupling clusters in different harmonic oscillator states with respect to their relative motion. Finally, using a resonating group method strategy we solve the generalized eigenvalue problem to obtain scattering channels. Structural clustering characteristics are discussed and the modified harmonic oscillator representation for scattering equations method is used to extract scattering observables.

Results: New methods for treating clustering problems have been put forward. We demonstrate broad applicability of the developed techniques. Examples highlight connections with algebraic techniques, and the role of approximations leading to algebraic limits is assessed using realistic examples. Various types of clustering characteristics are used to study alpha clustering in light nuclei that are relevant to currently ongoing experimental efforts. We demonstrate the emergence of strongly clustered bands of states in beryllium, triple alpha channels in ${}^{12}\mathrm{C}$, and molecular type clustering in ${}^{21}\mathrm{Ne}$. Starting from nucleon-nucleon interactions without any additional assumptions scattering phase shifts for alpha-alpha scattering are determined and shown to be consistent with those observed.

Conclusions: In this work we put forward a new configuration-interaction-based method that targets the physics of clustering, and further unifies nuclear structure and reactions. We provide detailed discussions and many examples highlighting features and advantages of the approach.

Low-spin states of ${}^{157}\mathrm{Dy}$ have been studied using the JUROGAM II array, following the ${}^{155}\mathrm{Gd}$ ($\alpha$, 2n) reaction at a beam energy of 25 MeV. The level scheme of ${}^{157}\mathrm{Dy}$ has been expanded with four new bands. Rotational structures built on the $\left[523\right]5/2^{-}$ and $\left[402\right]3/2^{+}$ neutron orbitals constitute new additions to the level scheme as do many of the inter- and intraband transitions. This manuscript also reports the observation of cross ${\mathrm{I}}^{+}\to {\left(\mathrm{I}–1\right)}^{-}$ and ${\mathrm{I}}^{-}\to {\left(\mathrm{I}–1\right)}^{+}$ E1 dipole transitions interlinking structures built on the $\left[523\right]5/2^{-}$ (band 5) and $\left[402\right]3/2^{+}$ (band 7) neutron orbitals. These interlacing band structures are interpreted as the bands of parity doublets with simplex quantum number $s=–i$ related to possible octupole correlations.

A method is proposed for determining the barrier transmission coefficient for the outgoing protons from the intranuclear cascade process in $(p,p^{\prime }x)$ reactions. In this method, the coefficient is defined as the ratio of the cross section of the proton-nucleus reaction to that of the neutron-nucleus reaction and is calculated by using empirical equations for the cross sections with no free parameters. The determined coefficient is incorporated into an intranuclear cascade model followed by an evaporation model, and the double-differential cross sections are calculated for $(p,p^{\prime }x)$ reactions around 50 MeV on heavy targets with $A\ge 120$. The present results agree well with experimental observations. Remarkably, the spectra for ${}^{209}\mathrm{Bi}$ and ${}^{197}\mathrm{Au}$ are accounted for even though the evaporation contributions are negligibly small.

The light-quark flavor dependence of the proton sea has been of great interest for many years because of its close connection with nonperturbative effects. One hypothesis is that this dependence arises from the pion cloud of the proton. We apply light-cone perturbation theory and experimental constraints to a chiral Lagrangian to compute the relevant Fock-space components of the nucleon wave function with well-defined uncertainties. Existing experimental information regarding the light-flavor sea is studied and predictions for future experimental results are provided. Future experiments have the ability to rule out this hypothesis and have profound implications for understanding the nucleon-nucleon force.

The excitations of nucleon resonances with hidden charm, $N_{c\overline{c}}^{*}$, in $\gamma p$ reactions are investigated by using the predictions from the available meson-baryon ($MB$) coupled-channel models of $N_{c\overline{c}}^{*}$, with $MB=\rho N,\omega N,J/\psi N,\overline{D}{\mathrm{\Lambda }}_c,{\overline{D}}^{*}{\mathrm{\Lambda }}_c,\overline{D}{\mathrm{\Sigma }}_c,{\overline{D}}^{*}{\mathrm{\Sigma }}_c,\overline{D}{\mathrm{\Sigma }}_c^{*}$. For the $\gamma p\to J/\psi p$ process, we first apply the model of Donnachie and Landshoff to calculate the Pomeron-exchange amplitudes with the parameters determined from fitting the available total cross section data up to invariant mass $W=300$ GeV. We then add the resonant $\gamma p\to N_{c\overline{c}}^{*}\to J/\psi p$ amplitudes to examine the effects of $N_{c\overline{c}}^{*}$ excitations on the cross sections of $\gamma p\to J/\psi p$ in the near threshold energy region covered by the recent experiments at Jefferson Lab. The $N_{c\overline{c}}^{*}\to MB$ transition matrix elements are determined from the partial decay widths predicted by the considered meson-baryon coupled-channel models of $N_{c\overline{c}}^{*}$. The $\gamma p\to N_{c\overline{c}}^{*}$ transition amplitudes are calculated from the vector meson dominance (VMD) model as $\gamma p\to Vp\to N_{c\overline{c}}^{*}$ with $V=\rho ,\omega ,J/\psi$. The total $\gamma p\to J/\psi p$ amplitudes then depend on an off-shell form factor, parametrized as $F_V\left(q^2\right)={\mathrm{\Lambda }}_V^4/\left[{\mathrm{\Lambda }}_V^4+{(q^2-m_V^2)}^2\right]$, which is needed to account for the $q^2$ dependence of the photon-vector meson coupling constant $\frac{e{m}_V^2}{f_V}$ of the VMD model. It was found that, with ${\mathrm{\Lambda }}_V=0.55$ GeV, the predicted total cross sections are within the range of the data in the energy region near the $J/\psi$ production threshold. We then demonstrate that the $N_{c\overline{c}}^{*}$ can be most easily identified in the differential cross sections at large angles where the contribution from Pomeron exchange becomes negligible. With the same VMD model and the same coupled-channel models of $N_{c\overline{c}}^{*}$, we also calculate the resonant amplitudes for the $\gamma p\to Vp\to N_{c\overline{c}}^{*}\to {\overline{D}}^0{\mathrm{\Lambda }}_c^{+}\left({\overline{D}}^{*0}{\mathrm{\Lambda }}_c^{+}\right)$ processes. By adding the nonresonant amplitudes due to the exchange of ${\overline{D}}^{*0}$ (${\overline{D}}^0$), we then predict the cross sections of $\gamma p\to {\overline{D}}^0{\mathrm{\Lambda }}_c^{+}\left({\overline{D}}^{*0}{\mathrm{\Lambda }}_c^{+}\right)$ for additional experimental tests of the available meson-baryon coupled-channel models of $N_{c\overline{c}}^{*}$.

Background: Near-threshold $\alpha$-clustered states in light nuclei have been postulated to have a structure consisting of a diffuse gas of $\alpha$ particles which condense into the $0s$ orbital. Experimental evidence for such a dramatic phase change in the structure of the nucleus has not yet been observed.

Purpose: To understand the role of $\alpha$ condensation in light nuclei experimentally.

Method: To examine signatures of this $\alpha$ condensation, a compound nucleus reaction using 160-, 280-, and 400-MeV ${}^{16}\mathrm{O}$ beams impinging on a carbon target was used to investigate the ${}^{12}\mathrm{C}({}^{16}\mathrm{O},7\alpha )$ reaction. This permits a search for near-threshold states in the $\alpha$-conjugate nuclei up to ${}^{24}\mathrm{Mg}$.

Results: Events up to an $\alpha$-particle multiplicity of seven were measured and the results were compared to both an extended Hauser-Feshbach calculation and the Fermi breakup model. The measured multiplicity distribution exceeded that predicted from a sequential decay mechanism and had a better agreement with the multiparticle Fermi breakup model. Examination of how these $7\alpha$ final states could be reconstructed to form ${}^8\mathrm{Be}$ and ${}^{12}\mathrm{C}\left({0_2}^{+}\right)$ showed a quantitative difference in which decay modes were dominant compared to the Fermi breakup model. No new states were observed in ${}^{16}\mathrm{O}, {}^{20}\mathrm{Ne}$, and ${}^{24}\mathrm{Mg}$ due to the effect of the $N-\alpha$ penetrability suppressing the total $\alpha$-particle dissociation decay mode.

Conclusion: The reaction mechanism for a high-energy compound nucleus reaction can only be described by a hybrid of sequential decay and multiparticle breakup. Highly $\alpha$-clustered states were seen which did not originate from simple binary reaction processes. Direct investigations of near-threshold states in $N-\alpha$ systems are inherently impeded by the Coulomb barrier prohibiting the observation of states in the $N-\alpha$ decay channel. No evidence of a highly clustered 15.1-MeV state in ${}^{16}\mathrm{O}$ was observed from $[{}^{28}\mathrm{Si}^{★},{}^{12}\mathrm{C}\left({0_2}^{+}\right)]{}^{16}\mathrm{O}\left({0_6}^{+}\right)$ when reconstructing the Hoyle state from three $\alpha$ particles. Therefore, no experimental signatures for $\alpha$ condensation were observed.

$\beta$-delayed one-neutron and two-neutron branching ratios $(P_{1n}$ and $P_{2n})$ have been measured in the decay of $A=84$ to 87 Ga isotopes at the Radioactive-Isotope Beam Factory (RIBF) at the RIKEN Nishina Center using a high-efficiency array of ${}^3\mathrm{He}$ neutron counters (BRIKEN). Two-neutron emission was observed in the decay of ${}^{84,85,87}\mathrm{Ga}$ for the first time and the branching ratios were measured to be $P_{2n}=1.6\left(2\right)\%,1.3\left(2\right)\%$, and $10.2{\left(28\right)}_{\mathrm{stat}}{\left(5\right)}_{\mathrm{sys}}\%$, respectively. One-neutron branching ratio of ${}^{87}\mathrm{Ga}\left(P_{1n}=81{\left(9\right)}_{\mathrm{stat}}{\left(8\right)}_{\mathrm{sys}}\%\right)$ and half-life of 29(4) ms were measured for the first time. The branching ratios of ${}^{86}\mathrm{Ga}$ were also measured to be $P_{1n}=74{\left(2\right)}_{\mathrm{stat}}{\left(8\right)}_{\mathrm{sys}}\%$ and $16.2{\left(9\right)}_{\mathrm{stat}}{\left(6\right)}_{\mathrm{sys}}\%$ with better precision than a previous study. The observation that $P_{1n}>P_{2n}$ for both ${}^{86,87}\mathrm{Ga}$ was unexpected and is interpreted as a signature of dominating one-neutron emission from the two-neutron unbound excited states in ${}^{86,87}\mathrm{Ge}$. In order to interpret the experimental results, shell-model and Hauser-Feshbach statistical model calculations of delayed particle and $\gamma$-ray emission probabilities were performed. This model framework reproduces the experimental results. The shell model alone predicts $P_{2n}$ significantly larger than $P_{1n}$ for the ${}^{87}\mathrm{Ga}$ decay, and it is necessary to invoke a statistical description to successfully explain the observation that $P_{1n}>P_{2n}$. Our new results demonstrate the relevance and importance of a statistical description of neutron emission for the prediction of the decay properties of multineutron emitters and that it must be included in the $r$-process modeling.

Strutinsky's method is reviewed through a new understanding. This method depends on two free parameters: The smoothing parameter and the order of the curvature correction. It turns out that this method is nothing but a compromise between two fundamental conditions which are the so-called asymptotic limit which comes from the so-called remainder which imposes a small as possible smoothing parameter and the smoothing condition which forces that parameter to be, at least, slightly larger than the intershell spacing. In this paper, to find the best value of the smoothing parameter, a new criterion is proposed instead of the plateau condition. This new criterion is much more clear and free from ambiguities of the usual plateau condition. It is also found that the second free parameter, i.e., the order of the curvature correction, plays an accessory role since, it is connected intimately to the smoothing parameter, when the smoothing is realized. This paper provides a new and definitive insight into Strutinsky's method and its relationship with semiclassical methods.

Cross sections for 34 proton-induced nuclear reactions on isotopically enriched molybdenum (${}^{92,94-98,100}\mathrm{Mo}$) leading to production of ${}^{92}\mathrm{Tc}$, ${}^{93\mathrm{m}}\mathrm{Tc}$, ${}^{93\mathrm{g}}\mathrm{Tc}$, ${}^{94\mathrm{m}}\mathrm{Tc}$, ${}^{94\mathrm{g}}\mathrm{Tc}$, ${}^{95\mathrm{m}}\mathrm{Tc}$, ${}^{95\mathrm{g}}\mathrm{Tc}$, ${}^{96\mathrm{m}+\mathrm{g}}\mathrm{Tc}$, ${}^{97\mathrm{m}}\mathrm{Tc}$, ${}^{99\mathrm{m}}\mathrm{Tc}$, ${}^{101}\mathrm{Tc}$, ${}^{91(\mathrm{m}+\mathrm{g})}\mathrm{Mo}$, ${}^{93\mathrm{m}}\mathrm{Mo}$, ${}^{99}\mathrm{Mo}$, ${}^{89\mathrm{m}}\mathrm{Nb}$, ${}^{89\mathrm{g}}\mathrm{Nb}$, ${}^{91\mathrm{m}}\mathrm{Nb}$, ${}^{92\mathrm{m}}\mathrm{Nb}$, ${}^{95\mathrm{m}}\mathrm{Nb}$, ${}^{95\mathrm{g}}\mathrm{Nb}$, ${}^{96}\mathrm{Nb}$, and ${}^{97\mathrm{m}+\mathrm{g}}\mathrm{Nb}$ were measured in the energy range 8–19 MeV with the activation method using individual irradiations. The experimental data were compared with published data from natural abundance and isotopically enriched targets as well as with the predictions of the nuclear reaction code talys. Special attention was given to the medically relevant ${}^{100}\mathrm{Mo}$($p,2n$)${}^{\mathrm{99m}}\mathrm{Tc}$ and ${}^{100}\mathrm{Mo}$($p,pn$)${}^{99}\mathrm{Mo}$ as well as nine reaction cross sections that had not previously been measured in this energy range.

Calculations are presented for the time evolution of ${}^{240}\mathrm{Pu}$ from the proximity of the outer saddle point until the fission fragments are well separated, using the time-dependent density functional theory extended to superfluid systems. We have tested three families of nuclear energy density functionals and found that all functionals exhibit a similar dynamics: The collective motion is highly dissipative and with little trace of inertial dynamics, due to the one-body dissipation mechanism alone. This finding justifies the validity of using the overdamped collective motion approach and to some extent the main assumptions in statistical models of fission. This conclusion is robust with respect to the nuclear energy density functional used. The configurations and interactions left out of the present theory framework only increase the role of the dissipative couplings. An unexpected finding is varying the pairing strength within a quite large range has only minor effects on the dynamics. We find notable differences in the excitation energy sharing between the fission fragments in the cases of spontaneous and induced fission. With increasing initial excitation energy of the fissioning nucleus, more excitation energy is deposited in the heavy fragment, in agreement with experimental data on average neutron multiplicities.