scholarly journals Dessin d’enfant and a description of mutually nonlocal 7-branes without using branch cuts

2019 ◽  
Vol 100 (12) ◽  
Author(s):  
Shin Fukuchi ◽  
Naoto Kan ◽  
Shun’ya Mizoguchi ◽  
Hitomi Tashiro
Keyword(s):  
Branch Cuts

scholarly journals Pentagon functions for scattering of five massless particles

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
D. Chicherin ◽  
V. Sotnikov
Keyword(s):  
Phase Space ◽  
Numerical Evaluation ◽  
Public Library ◽  
Basis Set ◽  
Particle Scattering ◽  
Minimal Basis ◽  
Feynman Integrals ◽  
Analytic Expressions ◽  
Transcendental Functions ◽  
Branch Cuts

Abstract We complete the analytic calculation of the full set of two-loop Feynman integrals required for computation of massless five-particle scattering amplitudes. We employ the method of canonical differential equations to construct a minimal basis set of transcendental functions, pentagon functions, which is sufficient to express all planar and nonplanar massless five-point two-loop Feynman integrals in the whole physical phase space. We find analytic expressions for pentagon functions which are manifestly free of unphysical branch cuts. We present a public library for numerical evaluation of pentagon functions suitable for immediate phenomenological applications.

scholarly journals Treating branch cuts in quantum trajectory models for photoelectron holography

2018 ◽  
Vol 98 (6) ◽  
Author(s):  
A. S. Maxwell ◽  
S. V. Popruzhenko ◽  
C. Figueira de Morisson Faria
Keyword(s):  
Quantum Trajectory ◽  
Trajectory Models ◽  
Branch Cuts

scholarly journals A machine learning pipeline for autonomous numerical analytic continuation of Dyson-Schwinger equations

2022 ◽  
Vol 258 ◽  
pp. 09003
Author(s):  
Andreas Windisch ◽  
Thomas Gallien ◽  
Christopher Schwarzlmüller
Keyword(s):  
Machine Learning ◽  
Landau Gauge ◽  
Radial Component ◽  
Quark Propagator ◽  
Complex Domain ◽  
Iteration Step ◽  
Integration Contour ◽  
Self Energy ◽  
Contour Deformation ◽  
Branch Cuts

Dyson-Schwinger equations (DSEs) are a non-perturbative way to express n-point functions in quantum field theory. Working in Euclidean space and in Landau gauge, for example, one can study the quark propagator Dyson-Schwinger equation in the real and complex domain, given that a suitable and tractable truncation has been found. When aiming for solving these equations in the complex domain, that is, for complex external momenta, one has to deform the integration contour of the radial component in the complex plane of the loop momentum expressed in hyper-spherical coordinates. This has to be done in order to avoid poles and branch cuts in the integrand of the self-energy loop. Since the nature of Dyson-Schwinger equations is such, that they have to be solved in a self-consistent way, one cannot analyze the analytic properties of the integrand after every iteration step, as this would not be feasible. In these proceedings, we suggest a machine learning pipeline based on deep learning (DL) approaches to computer vision (CV), as well as deep reinforcement learning (DRL), that could solve this problem autonomously by detecting poles and branch cuts in the numerical integrand after every iteration step and by suggesting suitable integration contour deformations that avoid these obstructions. We sketch out a proof of principle for both of these tasks, that is, the pole and branch cut detection, as well as the contour deformation.

scholarly journals The Two-Phase Hell-Shaw Flow: Construction of an Exact Solution

2013 ◽  
Vol 18 (1) ◽  
pp. 249-257
Author(s):  
K.R. Malaikah
Keyword(s):  
Exact Solution ◽  
Velocity Potential ◽  
Time Dependent ◽  
Computational Domain ◽  
Phase Problem ◽  
Complex Velocity ◽  
Two Phase ◽  
Interface Evolution ◽  
Complex Velocity Potential ◽  
Branch Cuts

We consider a two-phase Hele-Shaw cell whether or not the gap thickness is time-dependent. We construct an exact solution in terms of the Schwarz function of the interface for the two-phase Hele-Shaw flow. The derivation is based upon the single-valued complex velocity potential instead of the multiple-valued complex potential. As a result, the construction is applicable to the case of the time-dependent gap. In addition, there is no need to introduce branch cuts in the computational domain. Furthermore, the interface evolution in a two-phase problem is closely linked to its counterpart in a one-phase problem

scholarly journals Understanding Branch Cuts of Expressions

2013 ◽  
pp. 136-151 ◽  
Author(s):  
Matthew England ◽  
Russell Bradford ◽  
James H. Davenport ◽  
David Wilson
Keyword(s):  
Branch Cuts

scholarly journals Handling of Complex Numbers in the CHProgramming Language

1993 ◽  
Vol 2 (3) ◽  
pp. 77-106 ◽  
Author(s):  
Harry H. Cheng
Keyword(s):  
Variable Number ◽  
Language Design ◽  
Complex Numbers ◽  
Computer Language ◽  
Real Numbers ◽  
Mathematical Functions ◽  
Complex Arithmetic ◽  
Complex Functions ◽  
Complex Features ◽  
Branch Cuts

The handling of complex numbers in the CHprogramming language will be described in this paper. Complex is a built-in data type in CH. The I/O, arithmetic and relational operations, and built-in mathematical functions are defined for both regular complex numbers and complex metanumbers of ComplexZero, Complexlnf, and ComplexNaN. Due to polymorphism, the syntax of complex arithmetic and relational operations and built-in mathematical functions are the same as those for real numbers. Besides polymorphism, the built-in mathematical functions are implemented with a variable number of arguments that greatly simplify computations of different branches of multiple-valued complex functions. The valid lvalues related to complex numbers are defined. Rationales for the design of complex features in CHare discussed from language design, implementation, and application points of views. Sample CHprograms show that a computer language that does not distinguish the sign of zeros in complex numbers can also handle the branch cuts of multiple-valued complex functions effectively so long as it is appropriately designed and implemented.

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