scholarly journals BARYON CHIRAL PERTURBATION THEORY IN MANIFESTLY LORENTZ-INVARIANT FORM

2006 ◽  
Vol 21 (04) ◽  
pp. 881-884 ◽  
Author(s):  
STEFAN SCHERER
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Effective Field ◽  
Renormalization Scheme ◽  
Perturbative Expansion ◽  
Power Counting ◽  
Counting Method ◽  
Chiral Perturbation ◽  
Effective Lagrangian ◽  
Expansion Scheme

A successful effective field theory program requires besides the most general effective Lagrangian a perturbative expansion scheme for observables in terms of a consistent power counting method. We discuss a renormalization scheme for manifestly Lorentz-invariant baryon chiral perturbation theory generating a simple and consistent power counting for renormalized diagrams. The approach may be used in an iterative procedure to renormalize higher-order loop diagrams and also allows for implementing a consistent power counting when vector mesons are explicitly included.

scholarly journals Chiral Perturbation Theory at NNNLO

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1262
Author(s):  
Nils Hermansson-Truedsson
Keyword(s):  
Field Theory ◽  
Perturbation Theory ◽  
Effective Field Theory ◽  
Chiral Perturbation Theory ◽  
Pion Mass ◽  
Effective Field ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Effective Lagrangian ◽  
Low Energies

Chiral perturbation theory is a much successful effective field theory of quantum chromodynamics at low energies. The effective Lagrangian is constructed systematically order by order in powers of the momentum p2, and until now the leading order (LO), next-to leading order (NLO), next-to-next-to leading order (NNLO) and next-to-next-to-next-to leading order (NNNLO) have been studied. In the following review we consider the construction of the Lagrangian and in particular focus on the NNNLO case. We in addition review and discuss the pion mass and decay constant at the same order, which are fundamental quantities to study for chiral perturbation theory. Due to the large number of terms in the Lagrangian and hence low energy constants arising at NNNLO, some remarks are made about the predictivity of this effective field theory.

scholarly journals The axion-baryon coupling in SU(3) heavy baryon chiral perturbation theory

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Thomas Vonk ◽  
Feng-Kun Guo ◽  
Ulf-G. Meißner
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Heavy Baryon ◽  
Power Counting ◽  
Flavor Symmetry ◽  
Chiral Perturbation ◽  
Third Order ◽  
Stellar Objects ◽  
The Past ◽  
Dense Nuclear Matter

Abstract In the past, the axion-nucleon coupling has been calculated in the framework of SU(2) heavy baryon chiral perturbation theory up to third order in the chiral power counting. Here, we extend these earlier studies to the case of heavy baryon chiral perturbation theory with SU(3) flavor symmetry and derive the axion coupling to the full SU(3) baryon octet, showing that the axion also significantly couples to hyperons. As studies on dense nuclear matter suggest the possible existence of hyperons in stellar objects such as neutron stars, our results should have phenomenological implications related to the so-called axion window.

scholarly journals LOWEST-LYING OCTET BARYON MASSES IN COVARIANT BARYON CHIRAL PERTURBATION THEORY

2014 ◽  
Vol 26 ◽  
pp. 1460068
Author(s):  
XIU-LEI REN ◽  
LISHENG GENG ◽  
JIE MENG ◽  
HIROSHI TOKI
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Mass Shell ◽  
Renormalization Scheme ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Octet Baryon ◽  
Self Consistent ◽  
Reasonable Description ◽  
Consistent Treatment

We report on a systematic study of the ground-state octet baryon masses in the covariant baryon chiral perturbation theory with the extended-on-mass-shell renormalization scheme up to next-to-next-to-next-to-leading order, taking into account the contributions of the virtual decuplet baryons. A reasonable description of the lattice results is achieved by fitting simultaneously all the publicly availablenf = 2 + 1lattice QCD data. It confirms that the various lattice simulations are consistent with each other. We stress that a self-consistent treatment of finite-volume corrections is important to obtain a χ2/d.o.f. about 1.

scholarly journals Systematizing and addressing theory uncertainties of unitarization with the Inverse Amplitude Method

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Alexandre Salas-Bernárdez ◽  
Felipe Llanes-Estrada ◽  
Juan Escudero-Pedrosa ◽  
José Antonio Oller
Keyword(s):  
Perturbation Theory ◽  
Partial Wave ◽  
Chiral Perturbation Theory ◽  
A Priori ◽  
Resonance Region ◽  
New Physics ◽  
Effective Field ◽  
Chiral Perturbation ◽  
Inverse Amplitude Method ◽  
Inverse Amplitude

Effective Field Theories (EFTs) constructed as derivative expansions in powers of momentum, in the spirit of Chiral Perturbation Theory (ChPT), are a controllable approximation to strong dynamics as long as the energy of the interacting particles remains small, as they do not respect exact elastic unitarity. This limits their predictive power towards new physics at a higher scale if small separations from the Standard Model are found at the LHC or elsewhere. Unitarized chiral perturbation theory techniques have been devised to extend the reach of the EFT to regimes where partial waves are saturating unitarity, but their uncertainties have hitherto not been addressed thoroughly. Here we take one of the best known of them, the Inverse Amplitude Method (IAM), and carefully following its derivation, we quantify the uncertainty introduced at each step. We compare its hadron ChPT and its electroweak sector Higgs EFT applications. We find that the relative theoretical uncertainty of the IAM at the mass of the first resonance encountered in a partial-wave is of the same order in the counting as the starting uncertainty of the EFT at near-threshold energies, so that its unitarized extension should a priori be expected to be reasonably successful. This is so provided a check for zeroes of the partial wave amplitude is carried out and, if they appear near the resonance region, we show how to modify adequately the IAM to take them into account.

scholarly journals Power counting in baryon chiral perturbation theory including vector mesons

2003 ◽  
Vol 575 (1-2) ◽  
pp. 11-17 ◽  
Author(s):  
Thomas Fuchs ◽  
Matthias R. Schindler ◽  
Jambul Gegelia ◽  
Stefan Scherer
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Power Counting ◽  
Vector Mesons ◽  
Chiral Perturbation

CHIRAL PERTURBATION THEORY AND ANOMALOUS PROCESSES

1993 ◽  
Vol 08 (18) ◽  
pp. 3045-3105 ◽  
Author(s):  
JOHAN BIJNENS
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Constituent Quark ◽  
Constituent Quark Model ◽  
Vector Meson Dominance ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Effective Lagrangian ◽  
Intrinsic Parity ◽  
Energy Processes

The application of chiral perturbation theory to low energy processes of abnormal intrinsic parity (anomalous) is discussed. The full infinite part at next-to-leading order is calculated. Estimates of the finite part of the effective Lagrangian from vector meson dominance and the chiral constituent quark model are obtained. This is then applied to decays of pseudoscalars to photon–photon and photon–three-pseudoscalar couplings.

scholarly journals SPIN POLARIZABILITY OF THE NUCLEON IN THE EFFECTIVE FIELD THEORY OF HEAVY BARYON

2006 ◽  
Vol 21 (19n20) ◽  
pp. 3947-3966
Author(s):  
K. B. VIJAYA KUMAR ◽  
YONG-LIANG MA ◽  
YUE-LIANG WU
Keyword(s):  
Field Theory ◽  
Perturbation Theory ◽  
Effective Field Theory ◽  
Chiral Perturbation Theory ◽  
Heavy Baryon ◽  
Effective Field ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Spin Polarizability ◽  
Large Correction

We have constructed a heavy baryon effective field theory with photon as an external field in accordance with the symmetry requirements similar to the heavy quark effective field theory. By treating the heavy baryon and antibaryon equally on the same footing in the effective field theory, we have calculated the spin polarizabilities γi, i = 1,…,4 of the nucleon at third order and at fourth-order of the spin-dependent Compton scattering. At leading order (LO), our results agree with the corresponding results of the heavy baryon chiral perturbation theory, at the next-to-leading order (NLO) the results show a large correction to the ones in the heavy baryon chiral perturbation theory due to baryon–antibaryon coupling terms. The low-energy theorem is satisfied both at LO and at NLO. The contributions arising from the heavy baryon–antibaryon vertex were found to be significant and the results of the polarizabilities obtained from our theory is much closer to the experimental data.

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.

Lowest-lying octet baryon masses up to $\mathcal{O}(p^4)$ in covariant baryon chiral perturbation theory

2014 ◽  
Vol 29 ◽  
pp. 1460215
Author(s):  
Xiu-Lei Ren ◽  
Lisheng Geng ◽  
Jie Meng ◽  
Hiroshi Toki
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Mass Shell ◽  
Renormalization Scheme ◽  
Low Energy ◽  
Tree Level ◽  
Chiral Perturbation ◽  
Octet Baryon ◽  
Reasonable Description ◽  
Energy Constants

In this talk, we report on a systematic study of the lowest-lying octet baryon masses in covariant baryon chiral perturbation theory with the extended-on-mass-shell renormalization scheme up to [Formula: see text]. By adjusting the low-energy constants, a reasonable description of the nf = 2 + 1 lattice results is achieved with χ2/d.o.f. about 1. It confirms that the various lattice simulations are consistent with each other. We also find that the virtual decuplet effects on the baryon masses cannot be disentangled from those of the virtual octet baryons and the tree level diagrams.

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