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Search: authors:"Alessandro Codello"

6 papers found.
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A unified universe

We present a unified evolution of the universe from very early times until the present epoch by including both the leading local correction \(R^2\) and the leading non-local term \(R\frac{1}{\square ^2}R\) to the classical gravitational action. We find that the inflationary phase driven by \(R^2\) term gracefully exits in a transitory regime characterized by coherent oscillations...

Leading CFT constraints on multi-critical models in d > 2

We consider the family of renormalizable scalar QFTs with self-interacting potentials of highest monomial ϕ m below their upper critical dimensions \( {d}_c=\frac{2m}{m-2} \), and study them using a combination of CFT constraints, Schwinger-Dyson equation and the free theory behavior at the upper critical dimension. For even integers m ≥ 4 these theories coincide with the Landau...

Conformal gauge-Yukawa theories away from four dimensions

We present the phase diagram and associated fixed points for a wide class of Gauge-Yukawa theories in d = 4 + ϵ dimensions. The theories we investigate involve non-abelian gauge fields, fermions and scalars in the Veneziano-Witten limit. The analysis is performed in steps, we start with QCD d and then we add Yukawa interactions and scalars which we study at next-to- and next-to...

Computing the effective action with the functional renormalization group

The “exact” or “functional” renormalization group equation describes the renormalization group flow of the effective average action \(\Gamma _k\). The ordinary effective action \(\Gamma _0\) can be obtained by integrating the flow equation from an ultraviolet scale \(k=\Lambda \) down to \(k=0\). We give several examples of such calculations at one-loop, both in renormalizable...

A functional RG equation for the c-function

After showing how to prove the integrated c-theorem within the functional RG framework based on the effective average action, we derive an exact RG flow equation for Zamolodchikov’s c-function in two dimensions by relating it to the flow of the effective average action. In order to obtain a non-trivial flow for the c-function, we will need to understand the general form of the...

Marginally deformed Starobinsky gravity

We show that quantum-induced marginal deformations of the Starobinsky gravitational action of the form R 2(1−α), with R the Ricci scalar and α a positive parameter smaller than one half, can generate sizable primordial tensor modes. We also suggest natural microscopic sources of these corrections and demonstrate that they generally lead to a nonzero and positive α. Furthermore we...