scholarly journals QED self-energies from lattice QCD without power-law finite-volume errors

2019 ◽  
Vol 100 (9) ◽  
Author(s):  
Xu Feng ◽  
Luchang Jin
Keyword(s):  
Lattice Qcd ◽  
Finite Volume ◽  
Power Law

scholarly journals DK I = 0, $$ D\overline{K} $$ I = 0, 1 scattering and the $$ {D}_{s0}^{\ast } $$(2317) from lattice QCD

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Gavin K. C. Cheung ◽  
◽  
Christopher E. Thomas ◽  
David J. Wilson ◽  
Graham Moir ◽  
...  
Keyword(s):  
Elastic Scattering ◽  
Scattering Amplitudes ◽  
Lattice Qcd ◽  
Finite Volume ◽  
Energy Region ◽  
Light Quark ◽  
Bound State ◽  
Vector Resonance ◽  
Quark Masses ◽  
Partial Waves

Abstract Elastic scattering amplitudes for I = 0 DK and I = 0, 1 $$ D\overline{K} $$ D K ¯ are computed in S, P and D partial waves using lattice QCD with light-quark masses corresponding to mπ = 239 MeV and mπ = 391 MeV. The S-waves contain interesting features including a near-threshold JP = 0+ bound state in I = 0 DK, corresponding to the $$ {D}_{s0}^{\ast } $$ D s 0 ∗ (2317), with an effect that is clearly visible above threshold, and suggestions of a 0+ virtual bound state in I = 0 $$ D\overline{K} $$ D K ¯ . The S-wave I = 1 $$ D\overline{K} $$ D K ¯ amplitude is found to be weakly repulsive. The computed finite-volume spectra also contain a deeply-bound D* vector resonance, but negligibly small P -wave DK interactions are observed in the energy region considered; the P and D-wave $$ D\overline{K} $$ D K ¯ amplitudes are also small. There is some evidence of 1+ and 2+ resonances in I = 0 DK at higher energies.

scholarly journals Staggered Semi-Implicit Hybrid Finite Volume/Finite Element Schemes for Turbulent and Non-Newtonian Flows

Mathematics ◽  
2021 ◽  
Vol 9 (22) ◽  
pp. 2972
Author(s):  
Saray Busto ◽  
Michael Dumbser ◽  
Laura Río-Martín
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Yield Stress ◽  
Finite Volume ◽  
Power Law ◽  
Source Terms ◽  
Cartesian Grids ◽  
Rans Equations ◽  
Edge Based ◽  
Finite Element Schemes

This paper presents a new family of semi-implicit hybrid finite volume/finite element schemes on edge-based staggered meshes for the numerical solution of the incompressible Reynolds-Averaged Navier–Stokes (RANS) equations in combination with the k−ε turbulence model. The rheology for calculating the laminar viscosity coefficient under consideration in this work is the one of a non-Newtonian Herschel–Bulkley (power-law) fluid with yield stress, which includes the Bingham fluid and classical Newtonian fluids as special cases. For the spatial discretization, we use edge-based staggered unstructured simplex meshes, as well as staggered non-uniform Cartesian grids. In order to get a simple and computationally efficient algorithm, we apply an operator splitting technique, where the hyperbolic convective terms of the RANS equations are discretized explicitly at the aid of a Godunov-type finite volume scheme, while the viscous parabolic terms, the elliptic pressure terms and the stiff algebraic source terms of the k−ε model are discretized implicitly. For the discretization of the elliptic pressure Poisson equation, we use classical conforming P1 and Q1 finite elements on triangles and rectangles, respectively. The implicit discretization of the viscous terms is mandatory for non-Newtonian fluids, since the apparent viscosity can tend to infinity for fluids with yield stress and certain power-law fluids. It is carried out with P1 finite elements on triangular simplex meshes and with finite volumes on rectangles. For Cartesian grids and more general orthogonal unstructured meshes, we can prove that our new scheme can preserve the positivity of k and ε. This is achieved via a special implicit discretization of the stiff algebraic relaxation source terms, using a suitable combination of the discrete evolution equations for the logarithms of k and ε. The method is applied to some classical academic benchmark problems for non-Newtonian and turbulent flows in two space dimensions, comparing the obtained numerical results with available exact or numerical reference solutions. In all cases, an excellent agreement is observed.

scholarly journals LATTICE QCD GLUON PROPAGATORS NEAR TRANSITION TEMPERATURE

2012 ◽  
Vol 27 (09) ◽  
pp. 1250050 ◽  
Author(s):  
V. G. BORNYAKOV ◽  
V. K. MITRJUSHKIN
Keyword(s):  
Transition Temperature ◽  
Lattice Qcd ◽  
Finite Volume ◽  
Momentum Space ◽  
Transition Point ◽  
Gluon Propagator ◽  
Landau Gauge ◽  
Volume Dependence ◽  
Gauge Fixing ◽  
Two Phases

Landau gauge gluon propagators are studied numerically in the SU (3) gluodynamics as well as in the full QCD with the number of flavors nF = 2 using efficient gauge fixing technique. We compare these propagators at temperatures very close to the transition point in two phases: confinement and deconfinement. The electric mass mE has been determined from the momentum space longitudinal gluon propagator. Gribov copy effects are found to be rather strong in the gluodynamics, while in the full QCD case they are weak ("Gribov noise"). Also we analyze finite volume dependence of the transverse and longitudinal propagators.

scholarly journals Finite-volume Hamiltonian method for coupled-channels interactions in lattice QCD

2014 ◽  
Vol 90 (5) ◽  
Author(s):  
Jia-Jun Wu ◽  
T.-S. H. Lee ◽  
A. W. Thomas ◽  
R. D. Young
Keyword(s):  
Lattice Qcd ◽  
Finite Volume ◽  
Hamiltonian Method ◽  
Coupled Channels

The Rheology of Blood Flow in a Branched Arterial System

2005 ◽  
Vol 15 (6) ◽  
pp. 398-405 ◽  
Author(s):  
Shewaferaw S. Shibeshi ◽  
William E. Collins
Keyword(s):  
Blood Flow ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Power Law ◽  
Numerical Study ◽  
Arterial System ◽  
Magnitude Distribution ◽  
Velocity Magnitude ◽  
Percentage Difference ◽  
Volume Method

AbstractBlood flow rheology is a complex phenomenon. Presently there is no universally agreed upon model to represent the viscous property of blood. However, under the general classification of non-Newtonian models that simulate blood behavior to different degrees of accuracy, there are many variants. The power law, Casson and Carreau models are popular non-Newtonian models and affect hemodynamics quantities under many conditions. In this study, the finite volume method is used to investigate hemodynamics predictions of each of the models. To implement the finite volume method, the computational fluid dynamics software Fluent 6.1 is used. In this numerical study the different hemorheological models are found to predict different results of hemodynamics variables which are known to impact the genesis of atherosclerosis and formation of thrombosis. The axial velocity magnitude percentage difference of up to 2 % and radial velocity difference up to 90 % is found at different sections of the T-junction geometry. The size of flow recirculation zones and their associated separation and reattachment point’s locations differ for each model. The wall shear stress also experiences up to 12 % shift in the main tube. A velocity magnitude distribution of the grid cells shows that the Newtonian model is close dynamically to the Casson model while the power law model resembles the Carreau model.

scholarly journals Finite volume dependence of hadron properties and lattice QCD

2005 ◽  
Vol 9 ◽  
pp. 321-330 ◽  
Author(s):  
Anthony W Thomas ◽  
Jonathan D Ashley ◽  
Derek B Leinweber ◽  
Ross D Young
Keyword(s):  
Lattice Qcd ◽  
Finite Volume ◽  
Volume Dependence

scholarly journals Finite Volume Simulation of Natural Convection for Power-Law Fluids with Temperature-Dependent Viscosity in a Square Cavity with a Localized Heat Source

2021 ◽  
Vol 39 (5) ◽  
pp. 1405-1416
Author(s):  
Hamza Daghab ◽  
Mourad Kaddiri ◽  
Said Raghay ◽  
Ismail Arroub ◽  
Mohamed Lamsaadi ◽  
...  
Keyword(s):  
Natural Convection ◽  
Heat Source ◽  
Finite Volume ◽  
Power Law ◽  
Numerical Study ◽  
Staggered Grid ◽  
Cooling Performance ◽  
Coupled Equations ◽  
Power Law Fluids ◽  
Power Law Index

In this paper, numerical study on natural convection heat transfer for confined thermo-dependent power-law fluids is conducted. The geometry of interest is a fluid-filled square enclosure where a uniform flux heating element embedded on its lower wall is cooled from the vertical walls while the remaining parts of the cavity are insulated, without slipping conditions at all the solid boundaries. The governing partial differential equations written in terms of non-dimensional velocities, pressure and temperature formulation with the corresponding boundary conditions are discretized using a finite volume method in a staggered grid system. Coupled equations of conservation are solved through iterative Semi Implicit Method for Pressure Linked Equation (SIMPLE) algorithm. The effects of pertinent parameters, which are Rayleigh number (103 ≤ Ra ≤ 106), power-law index (0.6 ≤ n ≤ 1.4), Pearson number (0 ≤ m ≤ 20) and length of the heat source (0.2 ≤ W ≤ 0.8) on the cooling performance are investigated. The results indicate that the cooling performance of the enclosure is improved with increasing Pearson and Rayleigh numbers as well as with decreasing power-law index and heat source length.

scholarly journals Lattice QCD and Three-Particle Decays of Resonances

2019 ◽  
Vol 69 (1) ◽  
pp. 65-107 ◽  
Author(s):  
Maxwell T. Hansen ◽  
Stephen R. Sharpe
Keyword(s):  
Scattering Amplitudes ◽  
Lattice Qcd ◽  
Finite Volume ◽  
First Principles ◽  
Quantization Condition ◽  
Infinite Volume ◽  
Numerical Implementation ◽  
Decay Channels ◽  
Particle Decays ◽  
The Relationship

Most strong-interaction resonances have decay channels involving three or more particles, including many of the recently discovered X, Y, and Z resonances. In order to study such resonances from first principles using lattice QCD, one must understand finite-volume effects for three particles in the cubic box used in calculations. We review efforts to develop a three-particle quantization condition that relates finite-volume energies to infinite-volume scattering amplitudes. We describe in detail the three approaches that have been followed, and present new results on the relationship between the corresponding results. We show examples of the numerical implementation of all three approaches and point out the important issues that remain to be resolved.

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