Course
19S1 D. Anselmi
Theories of gravitation
Program
Recent Papers

24A1 Damiano Anselmi
Cosmological inhomogeneities, primordial black holes, and a hypothesis on the death of the universeWe study the impact of the expansion of the universe on a broad class of objects, including black holes, neutron stars, white dwarfs, and others. ... (read more)

23A3 Damiano Anselmi
Gauge theories and quantum gravity in a finite interval of time, on a compact space manifoldWe study gauge theories and quantum gravity in a finite interval of time $ \tau $, on a compact space manifold $\Omega $. The initial, ... (read more)

23A2 Damiano Anselmi
Propagators and widths of physical and purely virtual particles in a finite interval of timeWe study the free and dressed propagators of physical and purely virtual particles in a finite interval of time $τ$ and on a compact space ... (read more)

23A1 Damiano Anselmi
Quantum field theory of physical and purely virtual particles in a finite interval of time on a compact space manifold: diagrams, amplitudes and unitarityWe provide a diagrammatic formulation of perturbative quantum field theory in a finite interval of time $τ$, on a compact space manifold $Ω$. We explain ... (read more)

22A5 Damiano Anselmi
A new quantization principle from a minimally non timeordered productWe formulate a new quantization principle for perturbative quantum field theory, based on a minimally non timeordered product, and show that it gives the theories ... (read more)

22A4 Damiano Anselmi
Purely virtual extension of quantum field theory for gauge invariant fields: quantum gravityQuantum gravity is extended to include purely virtual “cloud sectors”, which allow us to define a complete set of pointdependent observables, including a gauge invariant ... (read more)

22A3 Damiano Anselmi
Purely virtual extension of quantum field theory for gauge invariant fields: YangMills theoryWe extend quantum field theory by including purely virtual “cloud” sectors, to define physical offshell correlation functions of gauge invariant quark and gluon fields, without ... (read more)

22A2 Damiano Anselmi
Purely virtual particles versus LeeWick ghosts: physical PauliVillars fields, finite QED and quantum gravityWe reconsider the LeeWick (LW) models and compare their properties to the properties of the models that contain purely virtual particles. We argue against the ... (read more)

22A1 Damiano Anselmi
Dressed propagators, fakeon selfenergy and peak uncertaintyWe study the resummation of selfenergy diagrams into dressed propagators in the case of purely virtual particles and compare the results with those obtained for ... (read more)

21A5 Damiano Anselmi
Diagrammar of physical and fake particles and spectral optical theoremWe prove spectral optical identities in quantum field theories of physical particles (defined by the Feynman $i\epsilon $ prescription) and purely virtual particles (defined by ... (read more)

21A4 Damiano Anselmi, Kristjan Kannike, Carlo Marzo, Luca Marzola, Aurora Melis, Kristjan Müürsepp, Marco Piva and Martti Raidal
A fake doublet solution to the muon anomalous magnetic momentExtensions to the Standard Model that use strictly offshell degrees of freedom – the fakeons – allow for new measurable interactions at energy scales usually ... (read more)

21A3 Damiano Anselmi, Kristjan Kannike, Carlo Marzo, Luca Marzola, Aurora Melis, Kristjan Müürsepp, Marco Piva, Martti Raidal
Phenomenology of a Fake Inert Doublet ModelWe introduce a new way of modeling the physics beyond the Standard Model by considering fake, strictly offshell degrees of freedom: the fakeons. To demonstrate ... (read more)

21A2 Damiano Anselmi
Perturbation spectra and renormalizationgroup techniques in doublefield inflation and quantum gravity cosmologyWe study primordial cosmology with two scalar fields that participate in inflation at the same time, by coupling quantum gravity (i.e., the theory $R+R^2+C^2$ with ... (read more)

21A1 Damiano Anselmi, Filippo Fruzza and Marco Piva
Renormalizationgroup techniques for singlefield inflation in primordial cosmology and quantum gravityWe study inflation as a “cosmic” renormalizationgroup flow. The flow, which encodes the dependence on the background metric, is described by a running coupling $\alpha ... (read more)

20A5 Damiano Anselmi
Highorder corrections to inflationary perturbation spectra in quantum gravityWe compute the inflationary perturbation spectra and the quantity $r+8n_{T}$ to the nexttonexttoleading log order in quantum gravity with purely virtual particles (which means the ... (read more)
Archive for October 2019
19A3 Damiano Anselmi and Antonio Marino
Fakeons and microcausality: light cones, gravitational waves and the Hubble constant
The concept of fake particle, or “fakeon”, allows us to make sense of quantum gravity as an ultraviolet complete theory, by renouncing causality at very small distances. We investigate whether the violation of microcausality can be amplified or detected in the most common settings. We show that it is actually short range for all practical purposes. Due to our experimental limitations, the violation does not propagate along the light cones or by means of gravitational waves. In some cases, the universe even conspires to make the effect disappear. For example, the positivity of the Hubble constant appears to be responsible for the direction of time in the early universe.
Class. Quantum Grav. 37 (2020) 095003  DOI: 10.1088/13616382/ab78d2
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Book
14B1 D. Anselmi
Renormalization
Course on renormalization, taught in 2015.
Last update: September 15th 2023, 242 pages
The final (2023) edition is vaibable on Amazon:
Contents:
Preface
1. Functional integral
2. Renormalization
3. Renormalization group
4. Gauge symmetry
5. Canonical formalism
6. Quantum electrodynamics
7. NonAbelian gauge field theories
Notation and useful formulas
References
The pdf file of the 2015 Edition is available here: PDF
Sections
 Cosmology (14)
 Phenomenology beyond SM (7)
 Quantum gravity (59)
 Standard model (11)
 AdlerBardeen theorem (5)
 Background field method (3)
 Unitarity of quantum field theory (25)
 Purely virtual particles (44)
 Renormalization of general gauge theories (16)
 Fieldcovariant quantum field theory (4)
 Lorentz violating quantum field theory (11)
 Renormalization group (14)
 Infinite reduction of couplings (5)
 Regularization (5)
 Conformal field theory (20)
 Topological field theory (5)
 Instantons (4)
 Field redefinitions (4)
 Dimensional regularization (5)
 Philosophy of science (8)
 Biophysics (3)
 Videos (20)
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