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.

THE K+→π+π0γ(DE) DECAY IN CHIRAL PERTURBATION THEORY AT THE QUARK LEVEL

1993 ◽  
Vol 08 (17) ◽  
pp. 1599-1602 ◽  
Author(s):  
A.N. IVANOV ◽  
M. NAGY ◽  
N.I. TROITSKAYA
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Dominant Role ◽  
Low Energy ◽  
Chiral Perturbation ◽  
Direct Emission ◽  
Low Energies ◽  
Quark Level

The probability of the K+→π+π0γ (DE) decay with the direct emission of a photon is calculated. The strong low-energy interactions are accounted for within chiral perturbation theory at the quark level, based on the Extended Nambu-Jona-Lasinio (ENJL) model approximating QCD at low energies. The dominant role of chiral anomalies is confirmed.

THE $K_L^0\to \pi ^0 \gamma \gamma$ DECAY IN CHIRAL PERTURBATION THEORY BASED ON THE EXTENDED NAMBU-JONA-LASINIO MODEL

1992 ◽  
Vol 07 (21) ◽  
pp. 5115-5129 ◽  
Author(s):  
ANDREI N. IVANOV
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Chiral Limit ◽  
Decay Amplitude ◽  
Low Energy ◽  
Chiral Perturbation ◽  
Photon Exchange ◽  
Two Photon ◽  
Energy Approximation ◽  
Gamma Decay

The [Formula: see text] decay is analyzed within chiral perturbation theory based on the extended Nambu-Jona-Lasinio model, which is used as a low energy approximation of QCD. The two-photon spectrum of the [Formula: see text] decay and the value of the probability [Formula: see text] are obtained in good agreement with experimental data. It is shown that the CP-conserving two-photon exchange contribution to the [Formula: see text] decay mplitude is negligibly small compared to that of the CP-violating one-photon exchange. Also presented is the derivation of the low-energy theorem for the [Formula: see text] decay amplitude in the chiral limit.

scholarly journals The role of isospin filtering reactions in the S = −1 sector

2019 ◽  
Vol 199 ◽  
pp. 03008
Author(s):  
A. Feijoo ◽  
V.K. Magas ◽  
A. Ramos
Keyword(s):  
Perturbation Theory ◽  
High Spin ◽  
Chiral Perturbation Theory ◽  
Low Energy ◽  
Scattering Data ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Effective Lagrangian ◽  
Energy Constants

The present study reveals interesting constraining effects of isospin filtering reactions on the low energy constants present in meson-baryon chiral effective Lagrangian, particularly, on the next-to-leading order constants. Our model has been developed within the framework of Unitarized Chiral Perturbation Theory and has been fitted to two-body scattering data in the sector of S = −1. In addition, the model was further elaborated by means of the inclusion of high-spin hyperonic resonances.

scholarly journals Chiral Perturbation Theory vs. Linear Sigma Model in a Chiral Imbalance Medium

Particles ◽  
2020 ◽  
Vol 3 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Alexander Andrianov ◽  
Vladimir Andrianov ◽  
Domenec Espriu
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Sigma Model ◽  
Decay Constant ◽  
Low Energy ◽  
Linear Sigma Model ◽  
Chiral Perturbation ◽  
Large N ◽  
Energy Quantum ◽  
Energy Constants

We compare the chiral perturbation theory (ChPT) and the linear sigma model (LSM) as realizations of low energy quantum chromodynamics (QCD) for light mesons in a chirally-imbalanced medium. The relations between the low-energy constants of the chiral Lagrangian and the corresponding constants of the linear sigma model are established as well as the expressions for the decay constant of π -meson in the medium and for the mass of the a 0 . In the large N c count taken from QCD the correspondence of ChPT and LSM is remarkably good and provides a solid ground for the search of chiral imbalance manifestations in pion physics. A possible experimental detection of chiral imbalance (and therefore a phase with local parity breaking) is outlined in the charged pion decays inside the fireball.

scholarly journals PRESENT STATUS OF CHIRAL PERTURBATION THEORY

2005 ◽  
Vol 20 (08n09) ◽  
pp. 1613-1618 ◽  
Author(s):  
A. PICH
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Present Status ◽  
Resonance Region ◽  
Low Energy ◽  
Chiral Perturbation ◽  
Effective Lagrangian ◽  
Large N ◽  
Basic Ideas

The basic ideas and methods of chiral perturbation theory are briefly reviewed. I discuss the recent attempts to build an effective Lagrangian in the resonance region and summarize the known large–NC constraints on the low-energy chiral couplings.

scholarly journals LIGHT SCALARS AS TETRAQUARKS OR TWO-MESON STATES FROM LARGE-Nc AND UNITARIZED CHIRAL PERTURBATION THEORY

2004 ◽  
Vol 19 (39) ◽  
pp. 2879-2894 ◽  
Author(s):  
J. R. PELÁEZ
Keyword(s):  
Perturbation Theory ◽  
Scattering Amplitudes ◽  
Chiral Perturbation Theory ◽  
Low Energy ◽  
Effective Theory ◽  
Chiral Perturbation ◽  
Large N ◽  
Light Scalar ◽  
Meson States

By means of unitarized Chiral Perturbation Theory it is possible to obtain a remarkable description of meson–meson scattering amplitudes up to 1.2 GeV, and generate poles associated to scalar and vector resonances. Since Chiral Perturbation Theory is the QCD low energy effective theory, it is then possible to study its large-N c limit where [Formula: see text] states are easily identified. The vectors thus generated follow closely a [Formula: see text] behavior, whereas the light scalar poles follow the large-N c behavior expected for a dominant tetraquark or two-meson structure.

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
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