Publications associées à Amplitude de diffusion

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

Spatial symmetries in nonlocal multipolar metasurfaces

Olivier Martin, Karim Achouri, Ville Tuovi Tiukuvaara

We propose a framework that connects the spatial symmetries of a metasurface to its material parameter tensors and its scattering matrix. This provides a simple and universal way to effortlessly determine the properties of a metasurface scattering response ...

SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS2023

Where is M-theory in the space of scattering amplitudes?

Andrea Guerrieri, João Miguel Augusto Penedones Fernandes

We use the S-matrix bootstrap to carve out the space of unitary, analytic, crossing symmetric and supersymmetric graviton scattering amplitudes in nine, ten and eleven dimensions. We extend and improve the numerical methods of our previous work in ten dime ...

Springer Nature2023

An analytical toolkit for the S-matrix bootstrap

Miguel Alexandre Ribeiro Correia, Alexander Zhiboedov, Amit Sever

We revisit analytical methods for constraining the nonperturbative S-matrix of unitary, relativistic, gapped theories in d >= 3 spacetime dimensions. We assume extended analyticity of the two-to-two scattering amplitude and use it together with elastic uni ...

Springer Nature2021

Positive moments for scattering amplitudes

Riccardo Rattazzi, Francesco Riva, Marc Riembau Saperas, Brando Bellazzini

We find the complete set of conditions satisfied by the forward 2 -> 2 scattering amplitude in unitary and causal theories. These are based on an infinite set of energy dependent quantities (the arcs) which are dispersively expressed as moments of a positi ...

American Physical Society2021

Where Is String Theory in the Space of Scattering Amplitudes?

João Miguel Augusto Penedones Fernandes, Andrea Guerrieri

We use the S-matrix bootstrap to carve out the space of unitary, crossing symmetric and supersymmetric graviton scattering amplitudes in ten dimensions. We focus on the leading Wilson coefficient a controlling the leading correction to maximal supergravity ...

AMER PHYSICAL SOC2021

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

Semiclassical S-matrix and black hole entropy in dilaton gravity

Sergey Sibiryakov

We use complex semiclassical method to compute scattering amplitudes of a point particle in dilaton gravity with a boundary. This model has nonzero minimal black hole mass M-cr. We find that at energies below M-cr the particle trivially scatters off the bo ...

Springer Nature2020

Strongly Coupled Coherent Phonons in Single-Layer MoS2

Andras Kis, Dumitru Dumcenco

We present a transient absorption setup combining broadband detection over the visible-UV range with high temporal resolution (similar to 20 fs) which is ideally suited to trigger and detect vibrational coherences in different classes of materials. We gene ...

AMER CHEMICAL SOC2020

Multipolar origin of electromagnetic transverse force resulting from two-wave interference

Olivier Martin, Karim Achouri, Andrei Kiselev

We propose a theoretical study on the electromagnetic forces resulting from the superposition of TE and TM plane waves interacting with a sphere. Specifically, we first show that, under such an illumination condition, the sphere is subjected to a force tra ...

AMER PHYSICAL SOC2020

Dalitz plot analysis of the D+ -> K-K+K+ decay

Olivier Schneider, Aurelio Bay, Yiming Li, Guido Haefeli, Frédéric Blanc, Christoph Frei, Tatsuya Nakada, Michel De Cian, Luca Pescatore, Chitsanu Khurewathanakul, Matthieu Philippe Luther Marinangeli, Minh Tâm Tran, François Fleuret, Pietro Marino, Elena Graverini, Federico Leo Redi, Plamen Hristov Hopchev, Renato Quagliani, Maxime Schubiger, Federico Betti, Guido Andreassi, Violaine Bellée, Aravindhan Venkateswaran, Olivier Göran Girard, Luis Miguel Garcia Martin, Axel Kuonen, Vitalii Lisovskyi, Preema Rennee Pais, Katharina Müller, Jian Wang, Pavol Stefko, Mingkui Wang, Tara Nanut, Zhirui Xu, Maria Elena Stramaglia, Yi Zhang, Vladimir Macko, Guillaume Max Pietrzyk, Lei Zhang, Aleksey Vorobyev, Jessica Prisciandaro, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,

Bootstrapping QCD Using Pion Scattering Amplitudes

João Miguel Augusto Penedones Fernandes, Andrea Guerrieri

We consider the S-matrix bootstrap of four-dimensional scattering amplitudes with O(3) symmetry and no bound states. We explore the allowed space of scattering lengths which parametrize the interaction strength at threshold of the various scattering channe ...

2019

The S-matrix bootstrap IV: multiple amplitudes

João Miguel Augusto Penedones Fernandes, Jonathan Campbell Toledo

We explore the space of consistent three-particle couplings in Z(2)-symmetric two-dimensional QFTs using two first-principles approaches. Our first approach relies solely on unitarity, analyticity and crossing symmetry of the two-to-two scattering amplitud ...

Springer Nature2019

Polaritonic Cross Feshbach Resonance

Daniel Oberli, Marcia Portella Oberli, Mitchell David Anderson, Naotomo Takemura, Morteza Navadeh Toupchi

We demonstrate the existence of a cross Feshbach resonance by strongly driving a lower polariton mode and by monitoring in time the transmission of a short optical pulse at the energy of the upper polariton mode in a semiconductor microcavity. From the sig ...

2019

Broadband Nonreciprocal Acoustic Propagation Using Programmable Boundary Conditions: From Analytical Modeling to Experimental Implementation

Etienne Thierry Jean-Luc Rivet, Sami Driss Karkar, Gaël Matten

We theoretically, numerically and experimentally demonstrate the acoustic isolator effect in a one-dimensional waveguide with direction-dependent controlled boundary conditions. A theoretical model is used to explain the principle of nonreciprocal propagat ...

American Physical Society (APS)2019

Generalized resolution matrix for neutron spin-echo three-axis spectrometers

Thomas Keller, Felix Groitl

This article describes the energy resolution of spin-echo three-axis spectrometers (SE-TASs) by a compact matrix formalism. SE-TASs allow one to measure the line widths of elementary excitations in crystals, such as phonons and magnons, with an energy reso ...

INT UNION CRYSTALLOGRAPHY2018

Homogenization and Scattering Analysis of Second-Order Nonlinear Metasurfaces

Olivier Martin, Karim Achouri, Jérémy Butet, Gabriel David Bernasconi

We present an extensive discussion on the homogenization and scattering analysis of second-order nonlinear metasurfaces. We use the generalized sheet transition conditions (GSTCs) in the frequency-domain to model the electromagnetic responses of nonlinear ...

IEEE2018

Homogenization and Scattering Analysis of Second-Harmonic Generation in Nonlinear Metasurfaces

Olivier Martin, Karim Achouri, Jérémy Butet, Gabriel David Bernasconi

We propose an extensive discussion on the homogenization and scattering analysis of the second-order nonlinear metasurfaces. Our developments are based on the generalized sheet transition conditions (GSTCs) that are used to model the electromagnetic respon ...

2018

Structured amplitude and phase fields behind microstructures: The quest for high contrast modulation at proximity

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim, Krishnaparvathy Puthankovilakam, Johana Bernasconi

Microstructures can be used to realize repetitive and singular high contrast features at different distances behind a structure. For practical applications, the amplitude field needs to be considered. To realize defined amplitude features at long distances ...

Spie-Int Soc Optical Engineering2016

One-dimensional quantum magnetism in the anhydrous alum KTi(SO4)(2)

Henrik Moodysson Rønnow, Goran Nilsen

The anhydrous alum KTi(SO4)(2), where the Ti3+ (d(1), S = 1/2) ions form an anisotropic triangular lattice, has been prepared by a new hydrothermal route and characterized by magnetic susceptibility and neutron scattering measurements. Contrary to expectat ...

2015