Course
19R1 D. Anselmi
Theories of gravitation
Last update: October 5th 2018
PhD course – 54 hours – Videos of lectures and PDF files of slides
To be held in the first part of 2019 – Stay tuned
Program
Recent Papers

18A7 Damiano Anselmi
On the nature of the Higgs bosonSeveral particles are not observed directly, but only through their decay products. We consider the possibility that they might be fakeons, i.e. fake particles, which ... (read more)

18A6 Damiano Anselmi
Let the dice play GodWe define life as the amplification of quantum uncertainty up to macroscopic scales. A living being is any amplifier that achieves this goal. We argue ... (read more)

18A5 Damiano Anselmi
The correspondence principle in quantum field theory and quantum gravityWe discuss the fate of the correspondence principle beyond quantum mechanics, specifically in quantum field theory and quantum gravity, in connection with the intrinsic limitations ... (read more)

18A4 Damiano Anselmi
Fakeons, microcausality and the classical limit of quantum gravityWe elaborate on the idea of fake particle and its physical consequences. When a theory contains fakeons, the true classical limit is determined by the ... (read more)

18A3 Damiano Anselmi and Marco Piva
Quantum gravity, fakeons and microcausalityWe investigate the properties of fakeons in quantum gravity at one loop. The theory is described by a graviton multiplet, which contains the fluctuation $h_{\mu ... (read more)

18A2 Damiano Anselmi and Marco Piva
The ultraviolet behavior of quantum gravityA theory of quantum gravity has been recently proposed by means of a novel quantization prescription, which is able to turn the poles of the ... (read more)

18A1 Damiano Anselmi
Fakeons and LeeWick modelsThe “fakeon” is a fake degree of freedom, i.e. a degree of freedom that does not belong to the physical spectrum, but propagates inside the ... (read more)

17A3 Damiano Anselmi
On the quantum field theory of the gravitational interactionsWe study the main options for a unitary and renormalizable, local quantum field theory of the gravitational interactions. The first model is a LeeWick superrenormalizable ... (read more)

17A2 Damiano Anselmi and Marco Piva
Perturbative unitarity of LeeWick quantum field theoryWe study the perturbative unitarity of the LeeWick models, formulated as nonanalytically Wick rotated Euclidean theories. The complex energy plane is divided into disconnected regions ... (read more)

17A1 Damiano Anselmi and Marco Piva
A new formulation of LeeWick quantum field theoryThe LeeWick models are higherderivative theories that are claimed to be unitary thanks to a peculiar cancelation mechanism. In this paper, we provide a new ... (read more)

16A3 Damiano Anselmi
Algebraic cutting equationsThe cutting equations are diagrammatic identities that are used to prove perturbative unitarity in quantum field theory. In this paper, we derive algebraic, upgraded versions ... (read more)

16A2 Ugo G. Aglietti and Damiano Anselmi
Inconsistency of Minkowski higherderivative theoriesWe show that Minkowski higherderivative quantum field theories are generically inconsistent, because they generate nonlocal, nonHermitian ultraviolet divergences, which cannot be removed by means of ... (read more)

16A1 Damiano Anselmi
Aspects of perturbative unitarityWe reconsider perturbative unitarity in quantum field theory and upgrade several arguments and results. The minimum assumptions that lead to the largest time equation, the ... (read more)

15A4 Damiano Anselmi
Background field method and the cohomology of renormalizationUsing the background field method and the BatalinVilkovisky formalism, we prove a key theorem on the cohomology of perturbatively local functionals of arbitrary ghost numbers, ... (read more)

15A3 Damiano Anselmi
Some reference formulas for the generating functions of canonical transformationsWe study some properties of the canonical transformations in classical mechanics and quantum field theory and give a number of practical formulas concerning their generating ... (read more)
Anomalies
15A2 Damiano Anselmi
AdlerBardeen theorem and cancellation of gauge anomalies to all orders in nonrenormalizable theories
We prove the AdlerBardeen theorem in a large class of general gauge theories, including nonrenormalizable ones. We assume that the gauge symmetries are general covariance, local Lorentz symmetry and Abelian and nonAbelian YangMills symmetries, and that the local functionals of vanishing ghost numbers satisfy a variant of the KlubergStern–Zuber conjecture. We show that if the gauge anomalies are trivial at one loop, for every truncation of the theory there exists a subtraction scheme where they manifestly vanish to all orders, within the truncation. Outside the truncation the cancellation of gauge anomalies can be enforced by finetuning local counterterms. The framework of the proof is worked out by combining a recently formulated chiral dimensional regularization with a gauge invariant higherderivative regularization. If the higherderivative regularizing terms are placed well beyond the truncation, and the energy scale $\Lambda $ associated with them is kept fixed, the theory is superrenormalizable and has the property that, once the gauge anomalies are canceled at one loop, they manifestly vanish from two loops onwards by simple power counting. When the $\Lambda $ divergences are subtracted away and $\Lambda $ is sent to infinity, the anomaly cancellation survives in a manifest form within the truncation and in a nonmanifest form outside. The standard model coupled to quantum gravity satisfies all the assumptions, so it is free of gauge anomalies to all orders.
Phys. Rev. D 91 (2015) 105016  DOI: 10.1103/PhysRevD.91.105016
15A1 Damiano Anselmi
Ward identities and gauge independence in general chiral gauge theories
Using the BatalinVilkovisky formalism, we study the Ward identities and the equations of gauge dependence in potentially anomalous general gauge theories, renormalizable or not. A crucial new term, absent in manifestly nonanomalous theories, is responsible for interesting effects. We prove that gauge invariance always implies gauge independence, which in turn ensures perturbative unitarity. Precisely, we consider potentially anomalous theories that are actually free of gauge anomalies thanks to the AdlerBardeen theorem. We show that when we make a canonical transformation on the treelevel action, it is always possible to rerenormalize the divergences and refinetune the finite local counterterms, so that the renormalized $\Gamma $ functional of the transformed theory is also free of gauge anomalies, and is related to the renormalized $\Gamma $ functional of the starting theory by a canonical transformation. An unexpected consequence of our results is that the beta functions of the couplings may depend on the gaugefixing parameters, although the physical quantities remain gauge independent. We discuss nontrivial checks of highorder calculations based on gauge independence and determine how powerful they are.
Phys. Rev. D 92 (2015) 025027  DOI: 10.1103/PhysRevD.92.025027
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Book
14B1 D. Anselmi
Renormalization
Last update: May 9th 2015, 230 pages
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
Course on renormalization, taught in Pisa in 2015. (More chapters will be added later.)
Sections
 Quantum gravity (22)
 Standard model (5)
 AdlerBardeen theorem (5)
 Background field method (3)
 Unitarity of quantum field theory (12)
 Fakeons (8)
 Renormalization of general gauge theories (14)
 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 (3)
 Biophysics (1)
 Videos (3)
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