19R1 D. Anselmi
Theories of gravitation



Recent Papers

Martina Taiuti

We study phenomena predicted by a renormalizable, CPT invariant extension of the Standard Model that contains higher-dimensional operators and violates Lorentz symmetry explicitly at energies greater than some scale $\Lambda_{L}$. In particular, we consider the Cherenkov radiation in vacuo. In a rather general class of dispersion relations, there exists an energy threshold above which radiation is emitted. The threshold is enhanced in composite particles by a sort of kinematic screening mechanism. We study the energy loss and compare the predictions of our model with known experimental bounds on Lorentz violating parameters and observations of ultrahigh-energy cosmic rays. We argue that the scale of Lorentz violation $\Lambda_{L}$ (with preserved CPT invariance) can be smaller than the Planck scale, actually as small as $10^{14}$-$10^{15}$ GeV. Our model also predicts the Cherenkov radiation of neutral particles.


Phys. Rev. D 83 (2011) 056010 | DOI: 10.1103/PhysRevD.83.056010

arXiv: 1101.2019 [ hep-ph]

We study a QED extension that is unitary, CPT invariant and super-renormalizable, but violates Lorentz symmetry at high energies, and contains higher-dimension operators (LVQED). Divergent diagrams are only one- and two-loop. We compute the one-loop renormalizations at high and low energies and analyse the relation between them. It emerges that the power-like divergences of the low-energy theory are multiplied by arbitrary constants, inherited by the high-energy theory, and therefore can be set to zero at no cost, bypassing the hierarchy problem.


Phys. Rev. D 81 (2010) 085042 | DOI: 10.1103/PhysRevD.81.085042

arXiv: 0912.0113 [hep-ph]

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14B1 D. Anselmi

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Last update: May 9th 2015, 230 pages

1. Functional integral
2. Renormalization
3. Renormalization group
4. Gauge symmetry
5. Canonical formalism
6. Quantum electrodynamics
7. Non-Abelian gauge field theories
Notation and useful formulas

Course on renormalization, taught in Pisa in 2015. (More chapters will be added later.)