scholarly journals The pole structure of low energy πN scattering amplitudes

2019 ◽  
Vol 199 ◽  
pp. 02004
Author(s):  
Yu-Fei Wang
Keyword(s):  
Experimental Data ◽  
Perturbation Theory ◽  
Scattering Amplitudes ◽  
Low Energy ◽  
Tree Level ◽  
Chiral Perturbation ◽  
Left Hand ◽  
Pole Structure ◽  
Pion Nucleon ◽  
Branch Cuts

This report presents an investigation of the pion-nucleon elastic scattering in low energy region using a production representation of the partial wave S matrix. The phase shifts are separated into contributions from poles and branch cuts, where the left-hand cut term can be evaluated by tree-level covariant baryon chiral perturbation theory. A comparison between the sum of known contributions and the data in S- and P- wave channels is made. It is found that the known components in S11 and P11 channels are far from enough to saturate the corresponding experimental data, indicating the existence of low-lying hidden poles. The positions of those hidden poles are figured out and the physics behind them are explored.

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.

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 Spurious poles in the scattering of electric and magnetic charges

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
John Terning ◽  
Christopher B. Verhaaren
Keyword(s):  
Perturbation Theory ◽  
Scattering Amplitudes ◽  
Pair Production ◽  
Magnetic Particles ◽  
Single Photon ◽  
Low Energy ◽  
Magnetic Interactions ◽  
Parity Conservation ◽  
Non Local ◽  
The Way

Abstract Theories with both electric and magnetic charges (“mutually non-local” theories) have several major obstacles to calculating scattering amplitudes. Even when the interaction arises through the kinetic mixing of two, otherwise independent, U(1)’s, so that all low-energy interactions are perturbative, difficulties remain: using a self-dual, local formalism leads to spurious poles at any finite order in perturbation theory. Correct calculations must show how the spurious poles cancel in observable scattering amplitudes. Consistency requires that one type of charge is confined as a result of one of the U(1)’s being broken. Here we show how the constraints of confinement and parity conservation on observable processes manages to cancel the spurious poles in scattering and pair production amplitudes, paving the way for systematic studies of the experimental signatures of “dark” electric-magnetic processes. Along the way we demonstrate some novel effects in electric-magnetic interactions, including that the amplitude for single photon production of magnetic particles by electric particles vanishes.

Resonant and non-resonant contributions of B → K∗(p1,𝜖1){Kπ,ππ,KK} decay modes

2019 ◽  
Vol 34 (06) ◽  
pp. 1950043
Author(s):  
Mahboobeh Sayahi
Keyword(s):  
Experimental Data ◽  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Branching Ratio ◽  
Heavy Meson ◽  
Chiral Perturbation ◽  
Decay Modes ◽  
Qcd Factorization ◽  
Three Body ◽  
Good Agreement

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.

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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