Concept

Mass gap

Related publications (17)

Nonperturbative aspects of scattering amplitudes

In this thesis we study how physical principles imposed on the S-matrix, such as Lorentz invariance, unitarity, crossing symmetry and analyticity constrain quantum field theories at the nonperturbative level. We start with a pedagogical introduction to the ...

EPFL2023

IR side of positivity bounds

Francesco Riva, Marc Riembau Saperas, Brando Bellazzini

We show how calculable IR loop effects impact positivity bounds in effective field theories with causal and unitary UV completions. We identify infrared singularities that appear in dispersion relations at |t| less than or similar to m(2). In the massless ...

American Physical Society2022

Two-point functions and bootstrap applications in quantum field theories

Denis Karateev

We study two-point functions of local operators and their spectral representation in UV complete quantum field theories in generic dimensions focusing on conserved currents and the stress-tensor. We establish the connection with the central charges of the ...

Springer Nature2022

Gapped Goldstones at the cut-off scale: a non-relativistic EFT

Riccardo Rattazzi, Alexander Monin, Angelo Esposito, Gabriel Francisco Cuomo

At finite density, the spontaneous breakdown of an internal non-Abelian symmetry dictates, along with gapless modes, modes whose gap is fixed by the algebra and proportional to the chemical potential: the gapped Goldstones. Generically the gap of these sta ...

Springer Nature2021

Nonperturbative Mellin Amplitudes

João Pedro Alves Da Silva

Conformal field theory lies at the heart of two central topics in theoretical high energy physics: the study of quantum gravity and the mapping of quantum field theories through the renormalization group. In this thesis we explore a technique to study conf ...

EPFL2021

Bootstrapping massive quantum field theories

Denis Karateev, João Miguel Augusto Penedones Fernandes

We propose a new non-perturbative method for studying UV complete unitary quantum field theories (QFTs) with a mass gap in general number of spacetime dimensions. The method relies on unitarity formulated as positive semi-definiteness of the matrix of inne ...

Springer Nature2020

Generalization of the Haldane conjecture to SU(n) chains

Frédéric Mila, Miklos Lajko

Recently, SU(3) chains in the symmetric and self-conjugate representations have been studied using field theory techniques. For certain representations, namely rank-psymmetric ones with pnot a multiple of 3, it was argued that the ground state exhibits gap ...

2020

Large charge, semiclassics and superfluids : from broken symmetries to conformal field theories

Gabriel Francisco Cuomo

This thesis explores the application of semiclassical methods in the study of states with large quantum numbers for theories invariant under internal symmetries. In the first part of the thesis, we study zero-temperature superfluids. These provide a gener ...

EPFL2020

Walking, Weak first-order transitions, and Complex CFTs II. Two-dimensional Potts model at Q > 4

Bernardo Zan, Victor Gorbenko

We study complex CFTs describing fixed points of the two-dimensional Q-state Potts model with Q > 4. Their existence is closely related to the weak first-order phase transition and the "walking" renormalization group (RG) behavior present in the real Potts ...

2018

Zoology of condensed matter: framids, ordinary stuff, extra-ordinary stuff

Riccardo Rattazzi

We classify condensed matter systems in terms of the spacetime symmetries they spontaneously break. In particular, we characterize condensed matter itself as any state in a Poincare-invariant theory that spontaneously breaks Lorentz boosts while preserving ...

Springer Nature2015

Symmetric and asymmetric excitations of a strong-leg quantum spin ladder

Pierre Bouillot

The zero-field excitation spectrum of the strong-leg spin ladder (C7H10N)(2)CuBr4 is studied with a neutron time-of-flight technique. The spectrum is decomposed into its symmetric and asymmetric parts with respect to the rung momentum and compared with the ...

American Physical Society2013

Simple metastable de Sitter vacua in N=2 gauged supergravity

Claudio Scrucca, Paul Smyth, Francesca Catino

We construct a simple class of N=2 gauged supergravity theories that admit metastable de Sitter vacua, generalizing the recent work done in the context of rigid supersymmetry. The setup involves one hypermultiplet and one vector multiplet spanning suitably ...

Springer Nature2013

Cecotti-Fendley-Intriligator-Vafa index in a box

Alexander Monin

The Cecotti-Fendley-Intriligator-Vafa (CFIV) index in two-dimensional N = (2,2) models is revisited. We address the problem of "elementary" (nontopological) excitations over a kink solution, in the one-kink sector (using the Wess-Zumino or Landau-Ginzburg ...

2012

Scale-invariant alternatives to general relativity

Mikhail Chapochnikov, Diego Blas Temino, Daniel Zenhäusern

We study the general class of gravitational field theories constructed on the basis of scale invariance (and therefore absence of any mass parameters) and invariance under transverse diffeomorphisms, which are the 4-volume conserving coordinate transformat ...

American Physical Society2011

The lightest scalar in theories with broken supersymmetry

Claudio Scrucca, Leonardo Brizi

We study the scalar mass matrix of general supersymmetric theories with local gauge symmetries, and derive an absolute upper bound on the lightest scalar mass. This bound can be saturated by suitably tuning the superpotential, and its positivity therefore ...

Springer Nature2011

Vacuum Stability in Supersymmetric Effective Theories

Leonardo Brizi

The main topics discussed in this thesis are supersymmetric low-energy effective theories and metastability conditions in generic non-renormalizable models with global and local supersymmetry. In the first part we discuss the conditions under which the low ...

EPFL2011

Direct Search for Standard Model-Like Higgs Boson and Software Integration of Data Acquisition Cards

Cédric Potterat

The Large Hadron Collider (LHC) accelerator at CERN near Geneva is designed to collide protons with a centre-of-mass energy up to 14 TeV. It was tested at lower energy in November 2009. The world record collisions of beams of 1180 MeV was achieved. The LHC ...

EPFL2010