scholarly journals Lowest tensor-meson resonances contributions to the chiral perturbation theory low-energy coupling constants

1996 ◽  
Vol 53 (11) ◽  
pp. 6602-6607 ◽  
Author(s):  
D. Toublan
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Energy Coupling ◽  
Low Energy ◽  
Coupling Constants ◽  
Chiral Perturbation ◽  
Tensor Meson

ON THE SIGNIFICANCE OF RECENT LATTICE RESULTS FOR THE CHIRAL LAGRANGIAN

2008 ◽  
Vol 23 (21) ◽  
pp. 3187-3190
Author(s):  
H. LEUTWYLER
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Quark Condensate ◽  
Low Energy ◽  
Coupling Constants ◽  
Chiral Perturbation ◽  
Decay Constants ◽  
Energy Domain ◽  
The Masses ◽  
Ozi Rule

The report concerns only one of the issues discussed in my talk at ICFP 2007: the significance of recent lattice results for our understanding of the nonperturbative phenomena in the low energy domain of QCD. All of these results are consistent with the phenomenological estimates for the coupling constants of the chiral SU (2)× SU (2) Lagrangian and thereby corroborate the predictions based on these. In the case of SU (3)× SU (3), the results also confirm the old estimates obtained from chiral perturbation theory. In particular, the first two terms in the expansion of the masses and decay constants in powers of ms appear to represent a decent approximation for the full series. Some of the lattice results indicate that the quark condensate violates the OZI-rule rather strongly, but as there are some discrepancies concerning this issue, it is too early to draw conclusions.

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 New method for fitting the low-energy constants in chiral perturbation theory

2020 ◽  
Vol 102 (9) ◽  
Author(s):  
Qin-He Yang ◽  
Wei Guo ◽  
Feng-Jun Ge ◽  
Bo Huang ◽  
Hao Liu ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Low Energy ◽  
New Method ◽  
Chiral Perturbation ◽  
Energy Constants

CHIRAL PERTURBATION THEORY AT THE QUARK LEVEL

1992 ◽  
Vol 07 (29) ◽  
pp. 7305-7338 ◽  
Author(s):  
A.N. IVANOV ◽  
M. NAGY ◽  
N.I. TROITSKAYA
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Final State Interaction ◽  
Low Energy ◽  
Chiral Perturbation ◽  
Final State ◽  
Large N ◽  
Quark Level ◽  
Energy Approximation

The chiral perturbation theory is developed at the quark level within the extended Nambu-Jona-Lasinio model, which we used for the low-energy approximation of QCD in the leading order of the large N expansion. In terms of constituent-quark loop diagrams we analyze all of the main low-energy effects caused by the first order corrections in the current-quark-mass expansions. For the correct description of the η→3π decays we confirm the important role of the final-state interaction quoted by Gasser and Leutwyler.

scholarly journals Dissecting the $$\Delta I=1/2$$ rule at large $$N_c$$

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Andrea Donini ◽  
Pilar Hernández ◽  
Carlos Pena ◽  
Fernando Romero-López
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Low Energy ◽  
Kaon Decay ◽  
Chiral Perturbation ◽  
Kaon Decays ◽  
Diagrammatic Analysis ◽  
Good Agreement

Abstract We study the scaling of kaon decay amplitudes with the number of colours, $$N_c$$Nc, in a theory with four degenerate flavours, $$N_f=4$$Nf=4. In this scenario, two current-current operators, $$Q^\pm $$Q±, mediate $$\Delta S=1$$ΔS=1 transitions, such as the two isospin amplitudes of non-leptonic kaon decays for $$K\rightarrow (\pi \pi )_{I=0,2}$$K→(ππ)I=0,2, $$A_0$$A0 and $$A_2$$A2. In particular, we concentrate on the simpler $$K\rightarrow \pi $$K→π amplitudes, $$A^\pm $$A±, mediated by these two operators. A diagrammatic analysis of the large-$$N_c$$Nc scaling of these observables is presented, which demonstrates the anticorrelation of the leading $${{\mathcal {O}}}(1/N_c)$$O(1/Nc) and $${{\mathcal {O}}}(N_f/N_c^2)$$O(Nf/Nc2) corrections in both amplitudes. Using our new $$N_f=4$$Nf=4 and previous quenched data, we confirm this expectation and show that these corrections are naturally large and may be at the origin of the $$\Delta I=1/2$$ΔI=1/2 rule. The evidence for the latter is indirect, based on the matching of the amplitudes to their prediction in Chiral Perturbation Theory, from which the LO low-energy couplings of the chiral weak Hamiltonian, $$g^\pm $$g±, can be determined. A NLO estimate of the $$K \rightarrow (\pi \pi )_{I=0,2}$$K→(ππ)I=0,2 isospin amplitudes can then be derived, which is in good agreement with the experimental value.

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