ON THE PHENOMENOLOGICAL σ MODELS

1994 ◽  
Vol 09 (20) ◽  
pp. 3669-3681 ◽  
Author(s):  
N.N. ACHASOV ◽  
G.N. SHESTAKOV
Keyword(s):  
Chiral Symmetry ◽  
Scalar Meson ◽  
Phenomenological Description ◽  
Decay Widths ◽  
Scalar Resonances

The question of the phenomenological description of the broad scalar resonances compatible with chiral symmetry and unitarity is discussed within the linear σ model. It is shown that the naive consideration of the decay widths in the scalar-meson propagators is not an adequate approximation for the physical amplitudes. In this connection Refs. 8–10 are critically discussed. In particular, the K+→ π+π−e+ν and Ks→ππ decays are treated within the linear σ model with due regard for the unitarity.

scholarly journals The sigma-meson exchange contribution to the muonic hydrogen Lamb shift

2019 ◽  
Vol 212 ◽  
pp. 07003 ◽  
Author(s):  
A.E. Dorokhov ◽  
A.P. Martynenko ◽  
F.A. Martynenko ◽  
A.E. Radzhabov
Keyword(s):  
Experimental Data ◽  
Lamb Shift ◽  
Scalar Meson ◽  
Muonic Hydrogen ◽  
Meson Exchange ◽  
Exchange Contribution ◽  
Meson Coupling ◽  
Decay Widths ◽  
Precise Experimental Data ◽  
Sigma Meson

The sigma(ξ)meson exchange contribution to the potential of the muon-proton interactionin muonichydrogen inducedbythe ξ-meson coupling to two photons is estimated. The transition form factor ξ → γγ is deduced from the quark model and experimental data on the decay widths Γσγγ. It is shown that scalar meson exchange contribution to the Lamb shift in muonic hydrogen, △ELs(2P−2S ),is rather large and relevant for a comparison with coming precise experimental data.

Vacuum Structure, Chiral Symmetry Breaking and Radiative Decays of Vector Mesons

1997 ◽  
Vol 06 (01) ◽  
pp. 121-134
Author(s):  
A. R. Panda ◽  
K. C. Roy
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Radiative Decay ◽  
Constituent Quark ◽  
Chiral Symmetry Breaking ◽  
Vector Mesons ◽  
Model Calculations ◽  
Vacuum Structure ◽  
Quark Field ◽  
Decay Widths

The radiative decay widths of vector mesons were considered in a model involving chiral symmetry breaking through a nontrivial vacuum structure where the pion and kaon being treating consistently yield the constituent quark wave functions, approximately the same as that obtained from the gap equations and thus in a way determine the constituent quark field operators. Like its earlier success to some low energy hadronic phenomena, here also the model calculations of radiative decay widths of mesons are in reasonable agreements with other theoretical estimations as well as experimental measurements.

scholarly journals Inverse mass hierarchy of light scalar mesons driven by anomaly-induced flavor breaking

2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
Yoshiki Kuroda ◽  
Masayasu Harada ◽  
Shinya Matsuzaki ◽  
Daisuke Jido
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Scalar Meson ◽  
Chiral Symmetry Breaking ◽  
Linear Sigma Model ◽  
Mass Hierarchy ◽  
Scalar Mesons ◽  
Light Scalar ◽  
Symmetry Breaking Term ◽  
Breaking Term

Abstract We propose a novel mechanism to reproduce the observed mass hierarchy for scalar mesons lighter than 1 GeV (called the inverse hierarchy), regarding them as mesons made of a quark and an anti-quark ($q\bar{q}$ mesons). The source is provided by the SU(3) flavor-symmetry breaking induced by the U(1) axial anomaly. In particular, the anomaly term including the explicit chiral symmetry breaking plays a significant role in the light scalar meson spectrum. To be concrete, we construct a linear sigma model for scalar mesons of $q\bar{q}$ type together with their pseudoscalar chiral partners, including an anomaly-induced explicit chiral symmetry-breaking term. We find that, due to the proposed mechanism, the inverse hierarchy, i.e., $m\left[ a_0 (980) \right] \simeq m\left[ f_0 (980) \right] > m \left[ K_0^\ast (700) \right] > m \left[ f_0(500) \right]$, is indeed realized. Consequently, the quark content of $f_0 (500)$ is dominated by the isoscalar $\bar uu+ \bar dd$ component, and $f_0 (980)$ by the strange quark bilinear one, $s\bar{s}$.

CHIRAL SYMMETRY BREAKING IN A PHENOMENOLOGICAL DESCRIPTION OF THE QCD VACUUM

1992 ◽  
Vol 01 (01) ◽  
pp. 73-94 ◽  
Author(s):  
S. SCHRAMM ◽  
W. GREINER
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Phenomenological Description ◽  
Bcs Theory ◽  
Qcd Vacuum

Quark–antiquark condensation in the QCD groundstate is discussed in the framework of BCS theory. Adopting a phenomenological interaction between the quarks, the vacuum wavefunction is determined variationally. Taking these results, the properties of the vacuum and its excitations are determined. In addition the effect of instanton-type induced quark interactions is discussed.

scholarly journals LOW LYING SCALAR RESONANCES AND CHIRAL SYMMETRY

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2218-2225 ◽  
Author(s):  
HANQING ZHENG
Keyword(s):  
Chiral Symmetry ◽  
Theoretical Studies ◽  
Goldstone Bosons ◽  
Scalar Resonances ◽  
Chiral Partner

Current theoretical studies on the σ and κ resonances are reviewed. It is emphasized that all evidences accumulated so far are consistent with the picture that the σ meson is the chiral partner of the Nambu–Goldstone bosons in a linear realization of chiral symmetry.

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