DECAY SPECTRUM OF K+ → e+νeγ

2008 ◽  
Vol 23 (21) ◽  
pp. 3204-3208 ◽  
Author(s):  
C. H. CHEN ◽  
C. Q. GENG ◽  
C. C. LIH
Keyword(s):  
Perturbation Theory ◽  
Quark Model ◽  
Chiral Perturbation Theory ◽  
Form Factors ◽  
Light Front ◽  
Chiral Perturbation ◽  
Decay Spectrum

The form factors of the K+ → γ transition are studied in the light-front quark model and chiral perturbation theory of O(p6). The decay spectrum of K+ → e+νeγ, dominated by the structure dependent contribution, is illustrated in both models.

Light front Hamiltonian for boson form of QED (1 + 1) in Pauli–Villars regularization

2019 ◽  
Vol 34 (21) ◽  
pp. 1950113
Author(s):  
V. A. Franke ◽  
M. Yu. Malyshev ◽  
S. A. Paston ◽  
E. V. Prokhvatilov ◽  
M. I. Vyazovsky
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Chiral Condensate ◽  
Light Front ◽  
Coupling Constants ◽  
Hamiltonian Approach ◽  
Chiral Perturbation ◽  
Dimensional Models ◽  
Villars Regularization ◽  
Ultraviolet Regularization

Light front (LF) Hamiltonian for QED in [Formula: see text] dimensions is constructed using the boson form of this model with additional Pauli–Villars-type ultraviolet regularization. Perturbation theory, generated by this LF Hamiltonian, is proved to be equivalent to usual covariant chiral perturbation theory. The obtained LF Hamiltonian depends explicitly on chiral condensate parameters which enter in a form of some renormalization of coupling constants. The obtained results can be useful when one attempts to apply LF Hamiltonian approach for [Formula: see text]-dimensional models like QCD.

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 CHIRAL PERTURBATION THEORY STUDY OF THE AXIAL N → Δ(1232) TRANSITION

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2246-2249 ◽  
Author(s):  
L. S. GENG ◽  
J. MARTIN CAMALICH ◽  
L. ALVAREZ-RUSO ◽  
M. J. VICENTE VACAS
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Theoretical Study ◽  
Form Factors ◽  
Transition Form ◽  
Loop Order ◽  
Chiral Perturbation

We have performed a theoretical study of the axial Nucleon to Delta(1232) (N → Δ) transition form factors up to one-loop order in covariant baryon chiral perturbation theory within a formalism in which the unphysical spin-1/2 components of the Δ fields are decoupled.

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