Convergence issues in baryon chiral perturbation theory for the reaction π + N → 2π + N

2007 ◽  
Vol 85 (6) ◽  
pp. 663-669
Author(s):  
N Mobed ◽  
J Zhang ◽  
D Singh

We study the reaction π + N → 2π + N within the framework of heavy-baryon chiral perturbation theory of chiral order three. We find that contributions from amplitudes of chiral order three are large and play an essential role in reproducing the experimental data. In addition, we evaluate a polarization observable (target asymmetry) for the transverse polarization of the proton target and find that the asymmetry is generally small for the reaction under consideration. PACS Nos.: 25.80.Hp, 13.75.Gx, 11.30.Rd, 11.10.Ef

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Thomas Vonk ◽  
Feng-Kun Guo ◽  
Ulf-G. Meißner

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.


2019 ◽  
Vol 34 (06) ◽  
pp. 1950043
Author(s):  
Mahboobeh Sayahi

In this paper, the non-leptonic three-body decays [Formula: see text], [Formula: see text], [Formula: see text] are studied by introducing two-meson distribution amplitude for the [Formula: see text], [Formula: see text] and [Formula: see text] pairs in naive and QCD factorization (QCDF) approaches, such that the analysis is simplified into quasi-two body decays. By considering that the vector meson is being ejected in factorization, the resonant and non-resonant contributions are analyzed by using intermediate mesons in Breit–Wigner resonance formalism and the heavy meson chiral perturbation theory (HMChPT), respectively. The calculated values of the resonant and non-resonant branching ratio of [Formula: see text], [Formula: see text] and [Formula: see text] decay modes are compared with the experimental data. For [Formula: see text] and [Formula: see text], the non-resonant contributions are about 70–80% of experimental data, for which the total results by considering resonant contributions are in good agreement with the experiment.


2013 ◽  
Vol 88 (11) ◽  
Author(s):  
Yue-De Chen ◽  
Cong-Feng Qiao ◽  
Peng-Nian Shen ◽  
Zhuo-Quan Zeng

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