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Immanuel Ben Porat

Publications and source records attributed to Immanuel Ben Porat.

17 recordsLinked to original sources
arXiv2026

The relativistic Euler-Poisson equation as a mean-field limit

We adapt the renormalized energy method developed in \cite{duerinckx2020mean} in order to prove the monokinetic mean field limit for relativistic Newtonian dynamics. The resulting monokinetic PDE is the relativistic Euler-Poisson equation. Since the position evolves relativistically in comparison to the momentum, the kinetic part of the modulated energy has to adjusted, leading to further obstructions that are not present in the non-relativistic settings. A weak-strong stability principle for the relativistic Euler-Poisson equation is investigated, followed by a renormalization procedure leading to the mean-field limit. Our main result constitute the first mean-field limit for relativistic Coulomb flows.

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arXiv2026

Supercritical mean--field limit for magnetized Hamiltonian dynamic

The magnetized Vlasov--Poisson equation is a fundamental kinetic model for collisionless plasmas. We establish its quasi-neutral limit in two dimensions in the presence of a spatially inhomogeneous and time-dependent external magnetic field. In the same setting, we also establish the combined mean-field and quasi-neutral limit of the associated repulsive Coulomb particle system, thereby extending the results of \cite{han2021newton}. Both limits lead to the incompressible Euler equations with Lorentz forcing. A key structural feature is the pointwise skew-symmetry of the Lorentz operator, which produces exact cancellations in the modulated-energy estimates and is crucial for controlling the limiting dynamics. We further derive a closed vorticity formulation in which the sum of the fluid vorticity and the magnetic field is transported by the flow, coupled to an evolution equation for the spatial mean velocity. Finally, we establish global well-posedness of the resulting limiting system in the Lipschitz class.

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arXiv2026

From magnetized Coulombic quantum dynamics to magnetized fluids

We extend the quantum modulated energy developed in [17] in order to de- rive the magnetized pressureless Euler-Poisson equation as a semiclassical and mean field semiclassical limit from the magnetized Schrödinger-Poisson and von-Neumann equations, respectively. Local well-posedness of the underlying monokinetic PDE is also addressed. In both limits, the magnetic field is external and may be spatially non-uniform. Our results fall in the broader scope of semiclassical and quantum mean field limits for magnetized quantum dynamics.

math.AP↗
arXiv2026

Nonlocal-to-local limit for linear transport equations with measure initial data

We initiate the study of the nonlocal to local limit for linear transport equa- tions. A nonlocal version of the linear transport equation is introduced alongside an appropriate well-posedness theory for distributional solutions with measure initial data. We proceed by deriving the associated linear transport equation as a nonlocal-to-local limit. Some of the results apply in arbitrary dimension and for measure initial data.

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arXiv2026

Well-posedness and mean-field limit of discontinuous weighted dynamics via the relative entropy method

We consider deterministic particle dynamics with time evolving weights and their associated Kolmogorov equation and mean-field equation. We prove existence and unique- ness for the limit PDE alongside estimates on the growth of the logarithmic gradient as well as existence of weak solutions for the Kolmogorov equation satisfying an appropriate entropy inequality. We then apply these estimates and the relative entropy method as developed in [17], in order to derive the associated equation as a mean field limit. Our results cover both interactions and influence kernels with mild regularity assumptions.

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arXiv2025

Propagation of Velocity Moments for the Magnetized Vlasov-Poisson System with Space-Time Dependent Magnetic Fields

We prove that polynomial velocity moments of solutions to the 2D magnetized Vlasov-Poisson system and the 3D magnetized screened Vlasov-Poisson equation remain finite for all times, provided they are finite initially, even when the external magnetic field $B=B(t,x)$ is space-time dependent. We deduce propagation of regularity, thereby implying the existence of global classical solutions. Moreover, we prove optimal stability estimates in the kinetic-Wasserstein distance on par with the unmagnetised case.

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arXiv2025

Quantum Quasi-neutral Limits and Isothermal Euler Equations

We provide a rigorous justification of the semiclassical quasi-neutral and the quantum many-body limits to the isothermal Euler equations. We consider the nonlinear Schrödinger-Poisson-Boltzmann system under a quasi-neutral scaling and establish the convergence of its solutions to the isothermal Euler equations. Different from the previous results that dealt with the linear Poisson equations, the system under our consideration accounts for the exponential nonlinearity in the potential. A modulated energy method is adopted, allowing us to derive the stability estimates and asymptotics. Furthermore, we focus our analysis on the many-body quantum problem via the von Neumann equation and establish a mean-field limit in one dimension by using Serfaty's functional inequalities, and thus connecting the quantum many-body dynamics with the macroscopic hydrodynamic equations. A refined analysis of the quasi-neutral scaling for the massless systems is presented, and the well-posedness of the underlying quantum dynamics is established. Moreover, the construction of general admissible initial data is obtained. Our results provide a rigorous mathematical analysis for the derivation of quantum hydrodynamic models and their limits, contributing to the broader understanding of interactions between quantum mechanics and compressible fluid dynamics.

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arXiv2025

Singular flows with time-varying weights

We study the mean field limit for singular dynamics with time evolving weights. Our results are an extension of the work of Serfaty \cite{duerinckx2020mean} and Bresch-Jabin-Wang \cite{bresch2019modulated}, which consider singular Coulomb flows with weights which are constant time. The inclusion of time dependent weights necessitates the commutator estimates of \cite{duerinckx2020mean,bresch2019modulated}, as well as a new functional inequality. The well-posedness of the mean field PDE and the associated system of trajectories is also proved.

math.AP↗
arXiv2024

The graph limit for a pairwise competition model

This paper is aimed at extending the graph limit with time dependent weights obtained in [1] for the case of a pairwise competition model introduced in [10], in which the equation governing the weights involves a weak singularity at the origin. Well posedness for the graph limit equation associated with the ODE system of the pairwise competition model is also proved.

math.AP↗
arXiv2024

Pickl's Proof of the Quantum Mean-Field Limit and Quantum Klimontovich Solutions

This paper discusses the mean-field limit for the quantum dynamics of $N$ identical bosons in $\mathbf R^3$ interacting via a binary potential with Coulomb type singularity. Our approach is based on the theory of quantum Klimontovich solutions defined in [F. Golse, T. Paul, Commun. Math. Phys. 369 (2019), 1021-1053]. Our first main result is a definition of the interaction nonlinearity in the equation governing the dynamics of quantum Klimontovich solutions for a class of interaction potentials slightly less general than those considered in [T. Kato, Trans. Amer. Math. Soc. 70 (1951), 195-211]. Our second main result is a new operator inequality satisfied by the quantum Klimontovich solution in the case of an interaction potential with Coulomb type singularity. When evaluated on an initial bosonic pure state, this operator inequality reduces to a Gronwall inequality for a functional introduced in [P. Pickl, Lett. Math. Phys. 97 (2011), 151-164], resulting in a convergence rate estimate for the quantum mean-field limit leading to the time-dependent Hartree equation.

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arXiv2023

Mean field limit for one dimensional opinion dynamics with Coulomb interaction and time dependent weights

The mean field limit with time dependent weights for a 1D singular case, given by the attractive Coulomb interactions, is considered. This extends recent results [1,8] for the case of regular interactions. The approach taken here is based on transferring the kinetic target equation to a Burgers-type equation through the distribution function of the measures. The analysis leading to the stability estimates of the latter equation makes use of Kruzkov entropy type estimates adapted to deal with nonlocal source terms.

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arXiv2023

The magnetic Liouville equation as a semi-classical limit

The Liouville equation with non-constant magnetic field is obtained as a limit in the Planck constant \hbar of the Heisenberg equation with the same magnetic field. The convergence is with respect to an appropriate semi-classical pseudo distance, and consequently with respect to the Monge-Kantorovich distance. Uniform estimates both in εand \hbar are proved for the specific 2D case of a magnetic vector potential of the form \frac {1} εx^{\bot}. As an application, an observation inequality for the Heisenberg equation with a magnetic vector potential is obtained. These results are a magnetic variant of the works [7] and [8] respectively.

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arXiv2022

Derivation of Euler's equations of perfect fluids from von Neumann's equation with magnetic field

We give a rigorous derivation of the incompressible 2D Euler equation from the von Neumann equation with magnetic field. The convergence is with respect to the modulated energy functional, and implies weak convergence in the sense of measures. This is the quantum counterpart of theorem 1.2 in [Key: 10]. Our proof is based on a Gronwall estimate for the modulated energy functional, which in turn heavily relies on a recent functional inequality due to [Key: 20].

math.AP↗
arXiv2022

Convexity in Multivalued Harmonic Functions

We investigate variants of a Three Circles type Theorem in the context of \mathcal{Q}-valued functions. We prove some convexity inequalities related to the L^{2} growth function in the \mathcal{Q}-valued settings. Optimality of these inequalities and comparsion to the case of real valued harmonic functions is also discussed.

math.AP↗
arXiv2022

Local conditional regularity for the Landau equation with Coulomb potential

This paper studies the regularity of Villani solutions of the space homogeneous Landau equation with Coulomb interaction in dimension 3. Specifically, we prove that any such solution belonging to the Lebesgue space L_{t}^{\infty}L_{v}^{q} with q>3 in an open cylinder (0,S)\times B, where B is an open ball of \mathbb{R}^{3}, must have Holder continuous second order derivatives in the velocity variables, and first order derivative in the time variable locally in any compact subset of that cylinder.

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