Publications related to Imaginary number

Asymmetric phase modulation of light with parity-symmetry broken metasurfaces

The design of wavefront-shaping devices is conventionally approached using real-frequency modeling. However, since these devices interact with light through radiative channels, they are by default non-Hermitian objects having complex eigenvalues (poles and ...

Optica Publishing Group2023

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

Quand les artistes font forme en habitant ensemble. Usages, présences, imaginaires

Mathilde Coline Chénin

Taking root within a historical and transversal perspective of communities of artists at work, and of the relationship that they nourish with the places that host their creative activity, the present research intends to bring to light the grammars of "the ...

EPFL2022

Light absorption by brown carbon over the South-East Atlantic Ocean

Athanasios Nenes, Lu Zhang

Biomass burning emissions often contain brown carbon (BrC), which represents a large family of light-absorbing organics that are chemically complex, thus making it difficult to estimate their absorption of incoming solar radiation, resulting in large uncer ...

Copernicus GmbH2022

Realtime: making digital China

Realtime is an investigation about china’s digital and urban infrastructure, practices and imaginary spaces. Realtime attempts to capture the pace, scale and depth of china’s complex and changing reality. ...

EPFL Press2020

Apparent diffusion coefficient measured by diffusion MRI of moving and deforming domains

Jan Sickmann Hesthaven

The modeling of the diffusion MRI signal from moving and deforming organs such as the heart is challenging due to significant motion and deformation of the imaged medium during the signal acquisition. Recently, a mathematical formulation of the Bloch-Torre ...

Academic Press Inc - Elsevier Science2020

Standard-Model Prediction of epsilon(K) with Manifest Quark-Mixing Unitarity

Emmanuel Stamou

The parameter epsilon(K) describes CP violation in the neutral kaon system and is one of the most sensitive probes of new physics. The large uncertainties related to the charm-quark contribution to epsilon(K) have so far prevented a reliable standard-model ...

AMER PHYSICAL SOC2020

Loss of transverse Landau damping by noise and wakefield driven diffusion

Xavier Buffat, Sondre Vik Furuseth

Landau damping of coherent modes is strongly dependent on the exact shape of the particle bunches. One often assumes that the transverse distributions in high-energy hadron colliders can be approximated by Gaussian distributions, in acceptable agreement wi ...

2020

Robustness of Yu-Shiba-Rusinov resonances in the presence of a complex superconducting order parameter

Klaus Kern, Markus Etzkorn, Jacob Senkpiel

Robust quantum systems rely on having a protective environment with minimized relaxation channels. Super-conducting gaps play an important role in the design of such environments. The interaction of localized single spins with a conventional superconductor ...

AMER PHYSICAL SOC2019

Complex magnetoelectric effect in multiferroic composites: the case of PFN- PT/(Co,Ni)Fe2O4

Hadi Papi, Hossein Ahmadvand

We report a systematic study of the magnetoelectric (ME) voltage coefficient as a complex quantity in the particulate composite of ferroelectric solid solution 0.94Pb(Fe1/2N1/2)O-3-0.06PbTiO(3)(PFN-PT) with CoFe2O4(CFO) and NiFe2O4 (NFO) ferrites. The resu ...

2019

5 GHz laterally-excited bulk-wave resonators (XBARs) based on thin platelets of lithium niobate

Luis Guillermo Villanueva Torrijo, Soumya Yandrapalli, Victor Plessky

In a free-standing 400-nm-thick platelet of crystalline ZY-LiNbO3, narrow electrodes (500 nm) placed periodically with a pitch of a few microns can eXcite standing shear-wave bulk acoustic resonances (XBARs), by utilising lateral electric fields oriented p ...

2019

Automobility Beyond Car : Introducing a New Coordinate System for Transforming Urban Mobility

Farzaneh Bahrami

How is the future of automobility imagined today? What has structured such imaginary ? And what levers can steer its evolution towards a Post-Car World? These very three questions form the foundational motivations of this thesis. First, through a h ...

EPFL2017

A gauge invariant Debye mass and the complex heavy-quark potential

Yannis Burnier

Following the original idea of Debye, we define and extract a gauge-invariant screening mass from the complex static in-medium heavy-quark potential V-Q (Q) over bar, recently obtained from lattice QCD. To this end we derive a formula using concepts from b ...

Elsevier2016

The Bayesian reconstruction of the in-medium heavy quark potential from lattice QCD and its stability

Yannis Burnier

We report recent results of a non-perturbative determination of the static heavy-quark potential in quenched and dynamical lattice QCD at finite temperature. The real and imaginary part of this complex quantity are extracted from the spectral function of W ...

Amer Inst Physics2016

Low rank differential equations for Hamiltonian matrix nearness problems

Daniel Kressner

For a Hamiltonian matrix with purely imaginary eigenvalues, we aim to determine the nearest Hamiltonian matrix such that some or all eigenvalues leave the imaginary axis. Conversely, for a Hamiltonian matrix with all eigenvalues lying off the imaginary axi ...

Springer2015

Static Quark-Antiquark Potential in the Quark-Gluon Plasma from Lattice QCD

Yannis Burnier

We present a state-of-the-art determination of the complex valued static quark-antiquark potential at phenomenologically relevant temperatures around the deconfinement phase transition. Its values are obtained from nonperturbative lattice QCD simulations u ...

American Physical Society2015

Quarkonium spectral function in medium at next-to-leading order for any quark mass

Yannis Burnier

The vector channel spectral function at zero spatial momentum is calculated at next-to-leading order in thermal QCD for any quark mass. It corresponds to the imaginary part of the massive quark contribution to the photon polarisation tensor. The spectrum s ...

Springer Verlag2015

Asymptotic Behavior of Solutions to the Helmholtz Equations with Sign Changing Coefficients

Hoài-Minh Nguyên

This paper is devoted to the study of the behavior of the unique solution u delta is an element of H-0(1)(Omega), as delta -> 0, to the equation div(s(delta)A del u(delta)) + k(2)s(0)Sigma u(delta) = s0 f in Omega, where Omega is a smooth connected bounded ...

American Mathematical Society2015

Physically Based Modeling of Shear Modulus-Temperature Relationship for Thermosets

Thomas Keller, Anastasios Vassilopoulos, Wei Sun

A new physically based model for the simulation of the imaginary part of the shear modulus-temperature (G ''-T) curve of thermosets is introduced in this paper. The model is based on the modification of the G ''-T equation used for thermoplastic polymers v ...

Wiley-Blackwell2015

Torsion homology of arithmetic lattices and K-2 of imaginary fields

Vincent Emery

Let be a symmetric space of noncompact type. A result of Gelander provides exponential upper bounds in terms of the volume for the torsion homology of the noncompact arithmetic locally symmetric spaces . We show that under suitable assumptions on this resu ...

Springer Heidelberg2014