scholarly journals Two-point functions of quenched lattice QCD in Numerical Stochastic Perturbation Theory

2011 ◽  
Author(s):  
F. Di Renzo ◽  
E.-M. Ilgenfritz ◽  
H. Perlt ◽  
A. Schiller ◽  
C. Torrero
Keyword(s):  
Perturbation Theory ◽  
Lattice Qcd ◽  
Stochastic Perturbation

scholarly journals Two-point functions of quenched Lattice QCD in Numerical Stochastic Perturbation Theory. (I) The ghost propagator in Landau gauge

2010 ◽  
Vol 831 (1-2) ◽  
pp. 262-284 ◽  
Author(s):  
F. Di Renzo ◽  
E.-M. Ilgenfritz ◽  
H. Perlt ◽  
A. Schiller ◽  
C. Torrero
Keyword(s):  
Perturbation Theory ◽  
Lattice Qcd ◽  
Stochastic Perturbation ◽  
Landau Gauge ◽  
Ghost Propagator

scholarly journals Two-point functions of quenched lattice QCD in Numerical Stochastic Perturbation Theory. (II) The gluon propagator in Landau gauge

2011 ◽  
Vol 842 (1) ◽  
pp. 122-139 ◽  
Author(s):  
F. Di Renzo ◽  
E.-M. Ilgenfritz ◽  
H. Perlt ◽  
A. Schiller ◽  
C. Torrero
Keyword(s):  
Perturbation Theory ◽  
Lattice Qcd ◽  
Gluon Propagator ◽  
Stochastic Perturbation ◽  
Landau Gauge

scholarly journals Stochastic computation of g − 2 in QED

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Ryuichiro Kitano ◽  
Hiromasa Takaura ◽  
Shoji Hashimoto
Keyword(s):  
Perturbation Theory ◽  
Numerical Computation ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Stochastic Perturbation ◽  
Higher Order ◽  
Feynman Diagrams ◽  
Perturbative Series ◽  
Physical Quantities

Abstract We perform a numerical computation of the anomalous magnetic moment (g − 2) of the electron in QED by using the stochastic perturbation theory. Formulating QED on the lattice, we develop a method to calculate the coefficients of the perturbative series of g − 2 without the use of the Feynman diagrams. We demonstrate the feasibility of the method by performing a computation up to the α3 order and compare with the known results. This program provides us with a totally independent check of the results obtained by the Feynman diagrams and will be useful for the estimations of not-yet-calculated higher order values. This work provides an example of the application of the numerical stochastic perturbation theory to physical quantities, for which the external states have to be taken on-shell.

scholarly journals Preliminary results in unquenched numerical stochastic perturbation theory

2004 ◽  
Vol 129-130 ◽  
pp. 414-416
Author(s):  
F. Di Renzo ◽  
A. Mantovi ◽  
V. Miccio ◽  
L. Scorzato
Keyword(s):  
Perturbation Theory ◽  
Stochastic Perturbation ◽  
Preliminary Results

scholarly journals The Schrödinger Functional in Numerical Stochastic Perturbation Theory

2014 ◽  
Author(s):  
Dirk Hesse ◽  
Stefan Sint ◽  
Francesco Di Renzo ◽  
Mattia Dalla Brida ◽  
Michele Brambilla
Keyword(s):  
Perturbation Theory ◽  
Stochastic Perturbation

scholarly journals Nucleon’s energy–momentum tensor form factors in light-cone QCD

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
K. Azizi ◽  
U. Özdem
Keyword(s):  
Perturbation Theory ◽  
Lattice Qcd ◽  
Chiral Perturbation Theory ◽  
Light Cone ◽  
Energy Momentum Tensor ◽  
Form Factors ◽  
Momentum Tensor ◽  
Tensor Form ◽  
Chiral Perturbation ◽  
Theoretical Predictions

Abstract We use the energy–momentum tensor (EMT) current to compute the EMT form factors of the nucleon in the framework of the light cone QCD sum rule formalism. In the calculations, we employ the most general form of the nucleon’s interpolating field and use the distribution amplitudes (DAs) of the nucleon with two sets of the numerical values of the main input parameters entering the expressions of the DAs. The directly obtained results from the sum rules for the form factors are reliable at $$ Q^2\ge 1$$Q2≥1 GeV$$^2 $$2: to extrapolate the results to include the zero momentum transfer squared with the aim of estimation of the related static physical quantities, we use some fit functions for the form factors. The numerical computations show that the energy–momentum tensor form factors of the nucleon can be well fitted to the multipole fit form. We compare the results obtained for the form factors at $$ Q^2=0 $$Q2=0 with the existing theoretical predictions as well as experimental data on the gravitational form factor d$$_1^q(0)$$1q(0). For the form factors M$$_2^q (0)$$2q(0) and J$$^q(0)$$q(0) a consistency among the theoretical predictions is seen within the errors: our results are nicely consistent with the Lattice QCD and chiral perturbation theory predictions. However, there are large discrepancies among the theoretical predictions on d$$_1^q(0)$$1q(0). Nevertheless, our prediction is in accord with the JLab data as well as with the results of the Lattice QCD, chiral perturbation theory and KM15-fit. Our fit functions well define most of the JLab data in the interval $$ Q^2\in [0,0.4]$$Q2∈[0,0.4] GeV$$^2 $$2, while the Lattice results suffer from large uncertainties in this region. As a by-product, some mechanical properties of the nucleon like the pressure and energy density at the center of nucleon as well as its mechanical radius are also calculated and their results are compared with other existing theoretical predictions.

scholarly journals The nucleon mass in Nf=2 lattice QCD: finite size effects from chiral perturbation theory

2004 ◽  
Vol 689 (3) ◽  
pp. 175-194 ◽  
Author(s):  
A. Ali Khan ◽  
T. Bakeyev ◽  
M. Göckeler ◽  
T.R. Hemmert ◽  
R. Horsley ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Lattice Qcd ◽  
Chiral Perturbation Theory ◽  
Size Effects ◽  
Finite Size ◽  
Nucleon Mass ◽  
Chiral Perturbation ◽  
Finite Size Effects
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