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Non-Trivial Renormalization of Spin-Boson Models with Supercritical Form Factors
Marco Falconi, Benjamin Hinrichs, Javier Valent\'in Mart\'in
https://arxiv.org/abs/2508.00805

Non-Trivial Renormalization of Spin-Boson Models with Supercritical Form Factors
In this paper we construct the non-trivial, renormalized Hamiltonian for a class of spin-boson models with supercritical form factors, including the one describing the Weisskopf-Wigner spontaneous emission. The renormalization is performed through both a self-energy and mass renormalization, in the so-called Hamiltonian formalism of constructive quantum field theory, implemented by a non-unitary dressing transformation. This solves the problem of triviality for unitarily-renormalized supercriti…

Structure of renormalization constants for theories with multiple couplings in the MS-like subtraction schemes
Gleb Kovyrshin, Nikolai Meshcheriakov, Victoria Shatalova, Konstantin Stepanyantz
https://arxiv.org/abs/2509.03437

Structure of renormalization constants for theories with multiple couplings in the MS-like subtraction schemes
For theories with multiple couplings we construct simple expressions for the four-dimensional (or, in general, integer-dimensional) renormalization constants assuming that all divergences are logarithmical. These expressions allow relating all coefficients at $\varepsilon$-poles, logarithms, and (if exist) mixed terms to the coefficients of the renormalization group functions in any order of the perturbation theory for MS-like renormalization prescriptions. The result admits such a formulation …

Renormalization group flows in area-metric gravity
Johanna Borissova, Bianca Dittrich, Astrid Eichhorn, Marc Schiffer
https://arxiv.org/abs/2507.02034 http…

Renormalization group flows in area-metric gravity
We put forward the first analysis of renormalization group flows in an area-metric theory, motivated by spin-foam quantum gravity. Area-metric gravity contains the well-known length-metric degrees of freedom of standard gravity as well as additional shape-mismatching degrees of freedom. To be phenomenologically viable, the shape-mismatching degrees of freedom have to decouple under the renormalization group flow towards lower scales. We test this scenario by calculating the renormalization grou…

Renormalization-Free Galaxy Bias in Unified Lagrangian Perturbation Theory
Naonori Sugiyama
https://arxiv.org/abs/2509.04142 https://arxiv.org/pdf/2509.041…

Renormalization-Free Galaxy Bias in Unified Lagrangian Perturbation Theory
We present a renormalization-free framework for modeling galaxy bias based on Unified Lagrangian Perturbation Theory (ULPT). In this approach, the biased density fluctuation is built solely from Galileon-type operators associated with the intrinsic nonlinear growth of dark matter. This ensures the bias expansion is well defined at the field level, automatically satisfies statistical conditions of vanishing ensemble and volume averages, and removes the need for ad hoc renormalization. We derive …

Tensor Renormalization Group Meets Computer Assistance
Nikolay Ebel, Tom Kennedy, Slava Rychkov
https://arxiv.org/abs/2506.03247 https://

Tensor Renormalization Group Meets Computer Assistance
Tensor renormalization group, originally devised as a numerical technique, is emerging as a rigorous analytical framework for studying lattice models in statistical physics. Here we introduce a new renormalization map - the 2x1 map - which coarse-grains the lattice anisotropically by a factor of two in one direction followed by a 90-degree rotation. We develop a novel graphical language that translates the action of the 2x1 map into a system of inequalities on tensor components, with rigorous e…

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Renormalization of generalized spin--boson models with critical ultraviolet divergences
Benjamin Alvarez, Sascha Lill, Davide Lonigro, Javier Valent\'in Mart\'in
https://arxiv.org/abs/2508.00803

Renormalization of generalized spin--boson models with critical ultraviolet divergences
We provide a rigorous construction of generalized spin--boson models with commuting transition matrices and form factors exhibiting critical ultraviolet (UV) divergences. That is, we cover all divergences where a self-energy renormalization, but no non-Fock representation, is required. Our method is based on a direct definition of the renormalized Hamiltonian on a sufficiently large test domain, followed by a Friedrichs extension. We then prove that this Hamiltonian coincides with the one obtai…

Proper-time functional renormalization in $O(N)$ scalar models coupled to gravity
Alfio Bonanno, Emiliano Glaviano, Gian Paolo Vacca
https://arxiv.org/abs/2508.00807 https://

Proper-time functional renormalization in $O(N)$ scalar models coupled to gravity
We focus on the use of the functional Wilsonian renormalization group framework characterized by a proper time regulator and test its use in the search of the scaling solutions and the critical properties of an O(N)-invariant scalar field multiplet coupled to gravity in d=4 and d=3 dimensions. We employ the same background-fluctuation splitting and gauge fixing procedure, already adopted in a previous study based, instead, on the effective average action framework and a similar truncation of th…

Unitary and Analytic Renormalisation of Cosmological Correlators
Diksha Jain, Enrico Pajer, Xi Tong
https://arxiv.org/abs/2509.02696 https://arxiv.org/pdf/…

Unitary and Analytic Renormalisation of Cosmological Correlators
Loop contributions to cosmological correlators and to the associated wavefunction are of key theoretical and phenomenological interest. Here, we investigate and compare different renormalisation schemes proposed in the literature to handle ultraviolet divergences and develop new schemes adapting $η$ regulators to de Sitter spacetime. We focus on one-loop contributions to the quadratic wavefunction coefficient of a shift-symmetric massless scalar in de Sitter spacetime, which is a good toy mode…