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Alessandro Vichi

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Related publications (21)

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The conformal bootstrap: Theory, numerical techniques, and applications

Alessandro Vichi

Conformal field theories have been long known to describe the fascinating universal physics of scale invariant critical points. They describe continuous phase transitions in fluids, magnets, and numerous other materials, while at the same time sit at the h ...

AMER PHYSICAL SOC2019

Bounding scalar operator dimensions in 4D CFT

Riccardo Rattazzi, Alessandro Vichi

In an arbitrary unitary 4D CFT we consider a scalar operator phi, and the operator phi(2) defined as the lowest dimension scalar which appears in the OPE phi x phi with a nonzero coefficient. Using general considerations of OPE, conformal block decompositi ...

Springer Nature2008

Carving out OPE space and precise O(2) model critical exponents

Alessandro Vichi, Ning Su

We develop new tools for isolating CFTs using the numerical bootstrap. A "cutting surface" algorithm for scanning OPE coefficients makes it possible to find islands in high-dimensional spaces. Together with recent progress in large-scale semidefinite progr ...

Springer Nature2020

A New Method to Explore Conformal Field Theories in Any Dimension

Alessandro Vichi

The thesis represents an investigation into Conformal Field Theories (CFT's) in arbitrary dimensions. We propose an innovative method to extract informations about CFT's in a quantitative way. Studying the crossing symmetry of the four point function of sc ...

EPFL2011

Bootstrapping traceless symmetric O(N) scalars

Alessandro Vichi, Maria Refinetti, Marten Jan Reehorst

We use numerical bootstrap techniques to study correlation functions of traceless sym-metric tensors of O(N) with two indices ti j. We obtain upper bounds on operator dimen-sions for all the relevant representations and several values of N. We discover sev ...

SCIPOST FOUNDATION2023

Theoretical constraints on the Higgs effective couplings

Riccardo Rattazzi, Alessandro Vichi

We derive constraints on the sign of couplings in an effective Higgs Lagrangian using prime principles such as the naturalness principle, global symmetries, and unitarity. Specifically, we study four dimension-six operators, O-H, O-y, O-g, and O-gamma, whi ...

Springer Nature2010

Bootstrapping Heisenberg magnets and their cubic instability

Alessandro Vichi, Ning Su

We study the critical O(3) model using the numerical conformal bootstrap. In particular, we use a recently developed cutting-surface algorithm to efficiently map out the allowed space of conformal field theory data from correlators involving the leading O( ...

American Physical Society2021

Mixed scalar-current bootstrap in three dimensions

Alessandro Vichi, Marten Jan Reehorst

We study the mixed system of correlation functions involving a scalar field charged under a global U(1) symmetry and the associated conserved spin-1 current J(mu). Using numerical bootstrap techniques we obtain bounds on new observables not accessible in t ...

Springer Nature2020

R-current three-point functions in 4d N=1 superconformal theories

Alessandro Vichi, Andrea Manenti

In 4d N = 1 superconformal field theories (SCFTs) the R-symmetry current, the stress-energy tensor, and the supersymmetry currents are grouped into a single object, the Ferrara-Zumino multiplet. In this work we study the most general form of three-point fu ...

Springer Nature2018

Bootstrapping mixed correlators in N=4 super Yang-Mills

Alessandro Vichi, Andrea Manenti

We perform a numerical bootstrap study of the mixed correlator system containing the half-BPS operators of dimension two and three in N = 4 Super Yang-Mills. This setup improves on previous works in the literature that only considered single correlators of ...

Springer Nature2021

Fermion conformal bootstrap in 4d

Alessandro Vichi, Denis Karateev

We apply numerical conformal bootstrap techniques to the four-point function of a Weyl spinor in 4d non-supersymmetric CFTs. We find universal bounds on operator dimensions and OPE coefficients, including bounds on operators in mixed symmetry representatio ...

Springer Nature2019

Implications of ANEC for SCFTs in four dimensions

Alessandro Vichi, Andrea Manenti

We explore consequences of the Averaged Null Energy Condition (ANEC) for scaling dimensions Delta of operators in four-dimensional N = 1 superconformal field theories. We show that in many cases the ANEC bounds are stronger than the corresponding unitarity ...

Springer Nature2020

One-loop adjoint masses for non-supersymmetric intersecting branes

Alessandro Vichi

We consider breaking of supersymmetry in intersecting D-brane configurations by slight deviation of the angles from their supersymmetric values. We compute the masses generated by radiative corrections for the ad joint scalars on the brane world-volumes. I ...

Springer Nature2011

Charting the space of 3D CFTs with a continuous global symmetry

João Miguel Augusto Penedones Fernandes, Alessandro Vichi

We study correlation functions of a conserved spin-1 current J in three dimensional Conformal Field Theories (CFTs). We investigate the constraints imposed by permutation symmetry and current conservation on the form of three point functions and the four p ...

Springer Nature2019

Carving out the space of 4D CFTs

Alessandro Vichi

We introduce a new numerical algorithm based on semidefinite programming to efficiently compute bounds on operator dimensions, central charges, and OPT coefficients in 4D conformal and N = 1 superconformal field theories. Using our algorithm, we dramatical ...

Springer Nature2012

Bounds in 4D conformal field theories with global symmetry

Riccardo Rattazzi, Alessandro Vichi

We explore the constraining power of OPE associativity in 4D conformal field theory with a continuous global symmetry group. We give a general analysis of crossing symmetry constraints in the 4-point function , where phi is ...

2011

Universal constraints on conformal operator dimensions

Alessandro Vichi

We continue the study of model-independent constraints on the unitary conformal field theories (CFTs) in four dimensions, initiated in [R. Rattazzi, V. S. Rychkov, E. Tonni, and A. Vichi, J. High Energy Phys. 12 (2008) 031]. Our main result is an improved ...

American Physical Society2009

T-parity, its problems and their solution

Alessandro Vichi, Duccio Pappadopulo

We point out a basic difficulty in the construction of little-Higgs models with T-parity which is overlooked by large part of the present literature. Almost all models proposed so far fail to achieve their goal: they either suffer from sizable electroweak ...

Springer Nature2011

Central charge bounds in 4D conformal field theory

Riccardo Rattazzi, Alessandro Vichi

We derive model-independent lower bounds on the stress tensor central charge C-T in terms of the operator content of a 4-dimensional conformal field theory. More precisely, C-T is bounded from below by a universal function of the dimensions of the lowest a ...

American Physical Society2011

Production of a composite Higgs boson

Alessandro Vichi

We present a model-independent prescription for computing the gluon fusion production rate of a composite Higgs boson, which arises as a pseudo-Nambu-Goldstone boson, using effective Lagrangians. The calculation incorporates three different effects due to ...

American Physical Society2011