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Concept

Landau pole

Related publications (22)

Measurement of the τ lepton polarization in Z boson decays in proton-proton collisions at √s=13 TeV

Jian Wang, Matthias Finger, Qian Wang, Yiming Li, João Miguel das Neves Duarte, Matthias Wolf, Varun Sharma, Yi Zhang, Tian Cheng, Yixing Chen, Alexis Kalogeropoulos, Ioannis Papadopoulos, Hua Zhang, Siyuan Wang, Xin Chen, Michele Bianco, Sebastiana Gianì, Sun Hee Kim, Rakesh Chawla, Jan Steggemann, Konstantin Androsov, Anna Mascellani, Federica Legger, Matteo Galli, Gabriele Grosso

The polarization of tau leptons is measured using leptonic and hadronic tau lepton decays in Z -> tau(+)tau(-) events in proton-proton collisions at root s = 13 TeV recorded by CMS at the CERN LHC with an integrated luminosity of 36.3 fb(-1). The measured ...

Springer Nature2024

Nonperturbative aspects of scattering amplitudes

Miguel Alexandre Ribeiro Correia

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

Landau levels of the Euler class topology

Oleg Yazyev, Yifei Guan

Two-dimensional systems with C2T (PT) symmetry exhibit the Euler class topology E is an element of Z in each two-band subspace realizing a fragile topology beyond the symmetry indicators. By systematically studying the energy levels of Euler insulating pha ...

AMER PHYSICAL SOC2022

The S-matrix Bootstrap Reloaded

Aditya Hebbar

Quantum field theories (QFTs) are the backbone upon which the edifice of modern physics is built. In this thesis we explore the S-matrix bootstrap which is a non-perturbative method that constrains the vast space of QFTs by using consistency conditions tha ...

EPFL2021

S-matrix bootstrap for effective field theories: massless pions

João Miguel Augusto Penedones Fernandes

We use the numerical S-matrix bootstrap method to obtain bounds on the two leading Wilson coefficients (or low energy constants) of the chiral lagrangian controlling the low-energy dynamics of massless pions. This provides a proof of concept that the numer ...

Springer Nature2021

A scattering amplitude in Conformal Field Theory

João Miguel Augusto Penedones Fernandes, Marco Meineri, Marc Gillioz

We define form factors and scattering amplitudes in Conformal Field Theory as the coefficient of the singularity of the Fourier transform of time-ordered correlation functions, as p(2) -> 0. In particular, we study a form factor F(s, t, u) obtained from a ...

Springer Nature2020

The S-matrix bootstrap. Part III: higher dimensional amplitudes

João Miguel Augusto Penedones Fernandes, Jonathan Campbell Toledo

We consider constraints on the S-matrix of any gapped, Lorentz invariant quantum field theory in 3+1 dimensions due to crossing symmetry, analyticity and unitarity. We extremize cubic couplings, quartic couplings and scattering lengths relevant for the ela ...

Springer Nature2019

Towards the renormalization group flow of Horava gravity in 3+1 dimensions

Sergey Sibiryakov, Mario Herrero Valea

We compute the renormalization group running of the Newton constant and the parameter lambda in (3 + 1)-dimensional projectable Horava gravity. We use the background-field method, expanding around configurations with flat spatial metric, but nonvanishing s ...

American Physical Society2019

Quantum phase transitions beyond Landau-Ginzburg theory in one-dimensional space revisited

Christopher Marc Mudry

The phase diagram of the quantum spin-1/2 antiferromagnetic J(1)-J(2) XXZ chain was obtained by Haldane using bosonization techniques [Haldane, Phys. Rev. B 25, 4925 (1982); 26, 5257 (1982)]. It supports three distinct phases for 0

2019

Perturbative and non-perturbative aspects of RG flows in quantum field theory

Lorenzo Vitale

This thesis explores two aspects of the renormalization group (RG) in quantum field theory (QFT). In the first part we study the structure of RG flows in general Poincaré-invariant, unitary QFTs, and in particular the irreversibility properties and the rel ...

EPFL2016

Constraints on perturbative RG flows in six dimensions

Lorenzo Vitale

When conformal field theories (CFTs) are perturbed by marginally relevant deformations, renormalization group (RG) flows ensue that can be studied with perturbative methods, at least as long as they remain close to the original CFT. In this work we study s ...

Springer Nature2016

Scale-invariant alternatives to general relativity. II. Dilaton properties

Mikhail Chapochnikov, Georgios Karananas

In the present paper, we revisit gravitational theories which are invariant under TDiffs-transverse (volume-preserving) diffeomorphisms and global scale transformations. It is known that these theories can be rewritten in an equivalent diffeomorphism-invar ...

American Physical Society2016

Exact diagonalization of HeisenbergSU(N)chains in the fully symmetric and antisymmetric representations

Frédéric Mila, Pierre Marcel Nataf

Motivated by recent experimental progress in the context of ultracold multicolor fermionic atoms in optical lattices, we have developed a method to exactly diagonalize the Heisenberg SU(N) Hamiltonian with several particles per site living in a fully symme ...

2016

Model-independent precision constraints on dimension-6 operators

Francesco Riva

We discuss electroweak precision constraints on dimension-6 operators in the effective theory beyond the standard model. We identify the combinations of these operators that are constrained by the pole observables (the W and Z masses and on-shell decays) a ...

Springer Nature2015

Spontaneously broken conformal symmetry: dealing with the trace anomaly

Mikhail Chapochnikov, Alexander Monin, Roberta Armillis

The majority of renormalizable field theories possessing the scale invariance at the classical level exhibits the trace anomaly once quantum corrections are taken into account. This leads to the breaking of scale and conformal invariance. At the same time ...

Springer Nature2013

Higgs couplings in composite models

Francesco Riva, Riccardo Torre

We study Higgs couplings in the composite Higgs model based on the coset SO(5)/SO(4). We show that the couplings to gluons and photons are insensitive to the elementary-composite mixings and thus not affected by light fermionic resonances. Moreover, at lea ...

American Physical Society2013

Asymptotic safety of gravity and the Higgs-boson mass

Mikhail Chapochnikov

If gravity is asymptotically safe, then the ultimate theory might be just the standard model (minimally supplemented by a few light particles to accommodate neutrino masses and oscillations, dark matter, and the baryon asymmetry of the Universe) plus gravi ...

SP MAIK Nauka/Interperiodica, Springer2012

The quantum mechanics of perfect fluids

Riccardo Rattazzi, Solomon G Shamsuddin Osman Endlich

We consider the canonical quantization of an ordinary fluid. The resulting long-distance effective field theory is derivatively coupled, and therefore strongly coupled in the UV. The system however exhibits a number of peculiarities, associated with the vo ...

Springer Nature2011

Asymptotic safety of gravity and the Higgs boson mass

Mikhail Chapochnikov

There are indications that gravity is asymptotically safe. The Standard Model (SM) plus gravity could be valid up to arbitrarily high energies. Supposing that this is indeed the case and assuming that there are no intermediate energy scales between the Fer ...

2010

On the coupling integrals arising in the method of moments formulation of laterally bounded structures

Juan Ramon Mosig, Ivica Stevanovic, Pedro Crespo Valero

A generic integral equation and method of moments formulation is presented for laterally bounded stratified media including planar metallization. The main asset of the developed approach is its flexibility, as it encompasses generic lateral boundary condit ...

Institute of Electrical and Electronics Engineers2008