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Search: authors:"Alessandro Codello"

6 papers found.
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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...

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...

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...

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...

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...