A point-by-point answer to the comment authored by S. Ayik and D. Lacroix is presented. At this point in time this text is not aimed at being submitted to Phys. Rev. C or any other journal, unless the authors of the comment choose to follow such an avenue. I also suggest a possible formulation of a stochastic mean field approach free of the difficulties in the stochastic mean field model due to Ayik [1]. I. REBUTTALAyik and Lacroix raise four points in their comment [2] and I shall address them in that order.

There has been much recent interest in nuclear fission, due in part to a new appreciation of its relevance to astrophysics, stability of superheavy elements, and fundamental theory of neutrino interactions. At the same time, there have been important developments on a conceptual and computational level for the theory. The promising new theoretical avenues were the subject of a workshop held at the University of York in October 2019; this report summarises its findings and recommendations.

Recent developments in theoretical modeling and in computational power have allowed us to make significant progress on a goal not achieved yet in nuclear theory: a fully microscopic theory of nuclear fission. The complete microscopic description remains a computationally demanding task, but the information that can be provided by current calculations can be extremely useful to guide and constrain phenomenological approaches. First, a truly microscopic framework that can describe the real-time dynamics of the fissioning system can justify or rule out assumptions and approximations incompatible with an accurate quantum treatment or with our understanding of the inter nucleon interactions. Second, the microscopic approach can be used to obtain trends such as: the excitation energy sharing mechanism between fission fragments (FFs) with increasing excitation energy of the fissioning system, the angular momentum content of the FFs, or even to compute observables that cannot be otherwise calculated in phenomenological approaches or even measured, as in the case of astronomical environments. Merely the characterization of the trends would be of great importance for various application. We present here arguments that a truly microscopic approach to fission does not support the assumption of adiabaticity of the large amplitude collective motion in fission, particularly starting from the outer saddle down to the scission configuration. Such an assumption legitimize the introduction of a collective potential energy surface and inertia tensor, which are the essential elements of many simpler theoretical approaches. The nuclear shape evolution it is paradoxically 3...4 times slower than it would have been in the case of a pure adiabatic motion, and it is strongly overdamped. We demonstrate that the FFs properties are defined only after the FFs become separated significantly from each other. I. THE PASTIn a matter of days after Hahn and Strassmann [1] communicated their yet unpublished results to Lise Meitner, she and her nephew Otto Frisch [2] understood that an unexpected and qualitatively new type of nuclear reaction has been put in evidence and they dubbed it nuclear fission, in analogy to cell divisions in biology. Until that moment in time nuclear fission was considered a totally unthinkable process [3,4], "as excluded by the small penetrability of the Coulomb barrier [5], indicated by the Gamov's theory of alpha-decay" [2]. Meitner and Frisch [2] also gave the correct physical interpretation of the nuclear fission mechanism. They understood that Bohr's compound nucleus [6] is formed after the absorption of a neutron, which eventually slowly evolves in shape, while the volume remains constant, and that the competition between the surface energy of a nucleus and its Coulomb energy leads to the eventual scission. Meitner and Frisch [2] also correctly estimated the total energy released in this process to be about 200 MeV. A few months later Bohr and Wheeler [7] filled in all the technical details and the long road to develo...

We outline an extension of the classical Langevin equation to a quantum formulation of the treatment of dissipation and fluctuations of all collective degrees of freedom and with an unitary evolution of a many-fermion system within a time-dependent density functional theory. We illustrate the method by computing the distribution of fission fragment yields for 258 Fm in a hydrodynamic approach.

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